Big New Genome Wide Association Study On Androgenetic Alopecia - Preprint

[InBeforeTheCure]

I just stumbled upon this Biorxiv preprint of a new GWAS run on a sample of over 50,000 men.

Abstract (http://biorxiv.org/content/early/2016/08/31/072306):

Male pattern baldness can have substantial psychosocial effects, and it has been phenotypically linked to adverse health outcomes such as prostate cancer and cardiovascular disease. We explored the genetic architecture of the trait using data from over 52,000 male participants of UK Biobank, aged 40-69 years. We identified over 250 independent novel genetic loci associated with severe hair loss. By developing a prediction algorithm based entirely on common genetic variants, and applying it to an independent sample, we could discriminate accurately (AUC = 0.82) between those with no hair loss from those with severe hair loss. The results of this study might help identify those at the greatest risk of hair loss and also potential genetic targets for intervention.

Full text: http://biorxiv.org/content/biorxiv/early/2016/08/31/072306.full.pdf

Table of Top 20 autosomal GWAS hits:

List of 112 associated autosomal genes:

Spoiler

GENE CHR START STOP NSNPS P
RSPO2 8 108911544 109095913 559 4.21E-23
EBF1 5 158122923 158526788 976 8.50E-22
PRR23B 3 138737873 138739768 1 3.03E-18
FAM53B 10 126307863 126432930 322 2.15E-17
NSF 17 44668035 44834830 90 2.34E-15
PDGFA 7 536895 559481 133 2.43E-15
WNT10A 2 219745255 219758651 22 3.14E-15
TBX15 1 119425666 119532179 327 3.39E-15
CENPW 6 126661253 126669754 14 3.48E-15
PLEKHM1 17 43513266 43568146 73 3.52E-15
GORAB 1 170501263 170522974 47 6.90E-15
FGF5 4 81187742 81212171 91 9.13E-15
KLF15 3 126061478 126076236 28 9.34E-15
CRHR1 17 43697710 43913194 362 1.99E-14
WNT3 17 44841686 44896082 107 2.20E-14
RUNX3 1 25226002 25291501 183 3.33E-14
C10orf11 10 77542519 78317130 2218 3.51E-14
TWIST2 2 239756673 239795893 159 4.47E-14
LOC100287387 2 239755218 239756320 3 6.97E-14
PRDM6 5 122424841 122523745 464 9.91E-14
OFCC1 6 9607550 9977826 1358 3.90E-13
MAPT 17 43971748 44105700 129 4.58E-13
METTL10 10 126447406 126480439 81 5.45E-13
WARS2 1 119573839 119683295 300 1.03E-12
SETBP1 18 42260138 42648475 973 2.42E-12
SLC14A2 18 42792947 43263072 1865 6.12E-12
KANSL1 17 44107282 44302740 179 1.35E-11
TOP1 20 39657462 39753127 196 1.74E-11
AUTS2 7 69063905 70257885 3099 4.81E-11
PRR23A 3 138722804 138725110 8 5.04E-11
DKK2 4 107842959 107957453 352 8.11E-11
BRE 2 28113482 28561768 1302 9.91E-11
FAF1 1 50906935 51425936 990 1.22E-10
C1orf127 1 11006530 11042094 141 1.24E-10
TRPS1 8 116420724 116681228 533 1.45E-10
YIPF4 2 32502958 32531658 84 1.54E-10
WNT6 2 219724546 219738954 22 2.09E-10
IRF4 6 391739 411443 82 2.28E-10
LGR4 11 27387508 27494334 247 3.18E-10
PLCG1 20 39766161 39804357 77 4.44E-10
PTHLH 12 28111017 28124916 53 5.79E-10
TRMT11 6 126307576 126360422 60 5.80E-10
TARDBP 1 11072679 11085549 27 5.83E-10
HINT3 6 126277861 126301390 42 6.22E-10
GFOD2 16 67708436 67753273 84 1.06E-09
MEMO1 2 32092892 32235698 373 1.53E-09
FADS2 11 61595713 61634825 140 1.68E-09
FADS1 11 61567097 61584529 30 1.79E-09
SSPN 12 26348269 26387710 127 2.15E-09
THADA 2 43457975 43823185 1227 2.45E-09
IQGAP1 15 90931473 91045475 374 2.84E-09
ATG7 3 11314010 11599139 828 3.51E-09
CLIC4 1 25071760 25170815 141 3.77E-09
RASA2 3 141205926 141331197 217 6.79E-09
MASP2 1 11086580 11107296 75 8.43E-09
ZHX3 20 39807089 39928739 285 9.61E-09
EIF3E 8 109213972 109260959 167 1.09E-08
SLC16A10 6 111408781 111544608 308 1.48E-08
CASZ1 1 10696661 10856707 553 1.54E-08
ATP6V0D1 16 67471917 67515089 71 1.75E-08
HDAC9 7 18126572 19036993 2945 1.79E-08
PAX3 2 223064606 223163715 362 1.90E-08
SRD5A2 2 31749656 31806040 178 1.90E-08
TSNAXIP1 16 67841010 67861971 38 2.39E-08
ZBTB38 3 141043055 141168634 336 2.39E-08
ACBD4 17 43209967 43221543 24 2.75E-08
SLC12A4 16 67977377 68002597 41 4.23E-08
PEX14 1 10535003 10690815 475 5.47E-08
EPB41L2 6 131160487 131384462 764 5.59E-08
XDH 2 31557188 31637611 324 6.62E-08
TMEM91 19 41869871 41889988 52 7.96E-08
PRDM4 12 108126643 108154914 89 8.53E-08
ZDHHC1 16 67428322 67450339 43 8.96E-08
SUCNR1 3 151591431 151599876 30 9.96E-08
PAX1 20 21686297 21696620 13 1.19E-07
ITCH 20 32951062 33099197 326 1.41E-07
B9D2 19 41860322 41870078 29 1.47E-07
VPS9D1 16 89773541 89787394 51 1.79E-07
C4orf22 4 81256874 81884910 2226 2.07E-07
RANBP10 16 67757005 67840555 153 2.21E-07
PWP1 12 108079590 108106257 90 2.40E-07
NUTF2 16 67880819 67905219 47 2.69E-07
PRKAG3 2 219687106 219696512 16 4.07E-07
HSD11B2 16 67465036 67471456 12 4.15E-07
TTC27 2 32853087 33046118 847 5.55E-07
RGS22 8 100973276 101118344 339 5.59E-07
CTCF 16 67596310 67673088 146 5.77E-07
METTL9 16 21610856 21668792 107 6.12E-07
NOP58 2 203130515 203168384 89 6.17E-07
TCF12 15 57210833 57580716 1181 6.34E-07
TMEM258 11 61556602 61560085 7 6.40E-07
LRP6 12 12268959 12419811 403 6.58E-07
ZNF462 9 109625378 109773807 331 7.61E-07
LRRC36 16 67360747 67419109 130 8.43E-07
SPAG17 1 118496288 118727848 528 1.04E-06
TCHH 1 152078793 152086556 16 1.05E-06
KIAA2012 2 202937978 202978327 147 1.14E-06
SUPT3H 6 44796469 45345670 1985 1.48E-06
CTNNB1 3 41240942 41281939 75 1.49E-06
PCGF3 4 699573 764428 328 1.83E-06
PLA2G15 16 68279247 68294961 38 1.86E-06
ELAVL4 1 50513686 50667540 294 1.90E-06
FAM175B 10 126490354 126525239 75 1.92E-06
ZNRF3 22 29279755 29453476 510 1.93E-06
FAM169B 15 98980391 99057611 281 2.17E-06
CENPT 16 67862060 67881361 33 2.24E-06
FYN 6 111982479 112194655 722 2.26E-06
ATP5SL 19 41937223 41945843 29 2.42E-06
REV3L 6 111620234 111804414 463 2.66E-06
MYRF 11 61520121 61555989 76 2.69E-06
RALY 20 32581732 32668067 157 2.70E-06
DLG5 10 79550549 79686348 492 2.73E-06

List of 13 X-chromosome genes:

Spoiler

GENE CHR START STOP NSNPS P
ITIH6 X 54775332 54824673 4 5.67E-05
KLF8 X 56258822 56314322 2 2.53E-08
FAAH2 X 57313110 57515629 8 9.96E-13
ARHGEF9 X 62854848 63005426 7 1.11E-11
MTMR8 X 63487961 63615333 4 1.12E-06
ZC4H2 X 64136250 64254593 3 5.32E-10
VSIG4 X 65241580 65259967 3 1.09E-35
HEPH X 65382433 65487231 5 1.16E-96
EDA2R X 65815479 65859140 2 5.13E-190
AR X 66763874 66944119 6 2.02E-269
OPHN1 X 67262186 67653299 41 4.25E-190
STARD8 X 67867511 67945684 12 1.56E-17
EDA X 68835911 69259322 40 5.54E-05

Some discussion from the paper:

As mentioned above, the GWAS identified 247 independent autosomal loci and 40 independent X chromosome loci. The top 20 hits from the autosomes were located in/near to genes that have been associated with, for example, hair growth/length in mice (FGF5) [20], grey hair (IRF4) [21], cancer (breast: MEMO1 [22], bladder: SLC14A2 [23]), histone acetylation (HDAC9), and frontotemporal dementia (MAPT) [24]. Two of the top 10 X chromosome SNPs were located in OPHN1, a gene previously associated with X-linked mental retardation [25].

Of the top autosomal gene-based findings (maximum P=3.1x10^-15), RSPO2 has been linked to hair growth in dogs. PGDFA has been linked to hair follicle development [26]; EBF1 is expressed in dermal papillae in mature hair follicles [27]; PRR23B is proximal to a GWAS hit for eyebrow thickness [21]; and WNT10A has been linked to both straight hair [28] and dry hair [29].

The top X chromosome gene-based findings included the androgen receptor (AR), which has been well established as a baldness associated gene [30], along with its upstream (EDA2R) and downstream (OPHN1) genes. EDA2R plays a role in the maintenance of hair and teeth as part of the tumor necrosis factor receptor. Onset of male pattern baldness could be influenced by EDA2R via activation of nuclear proto-oncoprotein c-Jun, which is linked to transcription activation of AR [31]. Two other genes included in the gene-based findings, OPHN1 and ZC4H2, have previously been associated with X-linked mental retardation [25, 32].

Seems simple, right?

 

[Roberto_72]

I just stumbled upon this Biorxiv preprint of a new GWAS run on a sample of over 50,000 men.

Abstract (http://biorxiv.org/content/early/2016/08/31/072306):



Full text: http://biorxiv.org/content/biorxiv/early/2016/08/31/072306.full.pdf

Table of Top 20 autosomal GWAS hits:



List of 112 associated autosomal genes:

Spoiler

GENE CHR START STOP NSNPS P
RSPO2 8 108911544 109095913 559 4.21E-23
EBF1 5 158122923 158526788 976 8.50E-22
PRR23B 3 138737873 138739768 1 3.03E-18
FAM53B 10 126307863 126432930 322 2.15E-17
NSF 17 44668035 44834830 90 2.34E-15
PDGFA 7 536895 559481 133 2.43E-15
WNT10A 2 219745255 219758651 22 3.14E-15
TBX15 1 119425666 119532179 327 3.39E-15
CENPW 6 126661253 126669754 14 3.48E-15
PLEKHM1 17 43513266 43568146 73 3.52E-15
GORAB 1 170501263 170522974 47 6.90E-15
FGF5 4 81187742 81212171 91 9.13E-15
KLF15 3 126061478 126076236 28 9.34E-15
CRHR1 17 43697710 43913194 362 1.99E-14
WNT3 17 44841686 44896082 107 2.20E-14
RUNX3 1 25226002 25291501 183 3.33E-14
C10orf11 10 77542519 78317130 2218 3.51E-14
TWIST2 2 239756673 239795893 159 4.47E-14
LOC100287387 2 239755218 239756320 3 6.97E-14
PRDM6 5 122424841 122523745 464 9.91E-14
OFCC1 6 9607550 9977826 1358 3.90E-13
MAPT 17 43971748 44105700 129 4.58E-13
METTL10 10 126447406 126480439 81 5.45E-13
WARS2 1 119573839 119683295 300 1.03E-12
SETBP1 18 42260138 42648475 973 2.42E-12
SLC14A2 18 42792947 43263072 1865 6.12E-12
KANSL1 17 44107282 44302740 179 1.35E-11
TOP1 20 39657462 39753127 196 1.74E-11
AUTS2 7 69063905 70257885 3099 4.81E-11
PRR23A 3 138722804 138725110 8 5.04E-11
DKK2 4 107842959 107957453 352 8.11E-11
BRE 2 28113482 28561768 1302 9.91E-11
FAF1 1 50906935 51425936 990 1.22E-10
C1orf127 1 11006530 11042094 141 1.24E-10
TRPS1 8 116420724 116681228 533 1.45E-10
YIPF4 2 32502958 32531658 84 1.54E-10
WNT6 2 219724546 219738954 22 2.09E-10
IRF4 6 391739 411443 82 2.28E-10
LGR4 11 27387508 27494334 247 3.18E-10
PLCG1 20 39766161 39804357 77 4.44E-10
PTHLH 12 28111017 28124916 53 5.79E-10
TRMT11 6 126307576 126360422 60 5.80E-10
TARDBP 1 11072679 11085549 27 5.83E-10
HINT3 6 126277861 126301390 42 6.22E-10
GFOD2 16 67708436 67753273 84 1.06E-09
MEMO1 2 32092892 32235698 373 1.53E-09
FADS2 11 61595713 61634825 140 1.68E-09
FADS1 11 61567097 61584529 30 1.79E-09
SSPN 12 26348269 26387710 127 2.15E-09
THADA 2 43457975 43823185 1227 2.45E-09
IQGAP1 15 90931473 91045475 374 2.84E-09
ATG7 3 11314010 11599139 828 3.51E-09
CLIC4 1 25071760 25170815 141 3.77E-09
RASA2 3 141205926 141331197 217 6.79E-09
MASP2 1 11086580 11107296 75 8.43E-09
ZHX3 20 39807089 39928739 285 9.61E-09
EIF3E 8 109213972 109260959 167 1.09E-08
SLC16A10 6 111408781 111544608 308 1.48E-08
CASZ1 1 10696661 10856707 553 1.54E-08
ATP6V0D1 16 67471917 67515089 71 1.75E-08
HDAC9 7 18126572 19036993 2945 1.79E-08
PAX3 2 223064606 223163715 362 1.90E-08
SRD5A2 2 31749656 31806040 178 1.90E-08
TSNAXIP1 16 67841010 67861971 38 2.39E-08
ZBTB38 3 141043055 141168634 336 2.39E-08
ACBD4 17 43209967 43221543 24 2.75E-08
SLC12A4 16 67977377 68002597 41 4.23E-08
PEX14 1 10535003 10690815 475 5.47E-08
EPB41L2 6 131160487 131384462 764 5.59E-08
XDH 2 31557188 31637611 324 6.62E-08
TMEM91 19 41869871 41889988 52 7.96E-08
PRDM4 12 108126643 108154914 89 8.53E-08
ZDHHC1 16 67428322 67450339 43 8.96E-08
SUCNR1 3 151591431 151599876 30 9.96E-08
PAX1 20 21686297 21696620 13 1.19E-07
ITCH 20 32951062 33099197 326 1.41E-07
B9D2 19 41860322 41870078 29 1.47E-07
VPS9D1 16 89773541 89787394 51 1.79E-07
C4orf22 4 81256874 81884910 2226 2.07E-07
RANBP10 16 67757005 67840555 153 2.21E-07
PWP1 12 108079590 108106257 90 2.40E-07
NUTF2 16 67880819 67905219 47 2.69E-07
PRKAG3 2 219687106 219696512 16 4.07E-07
HSD11B2 16 67465036 67471456 12 4.15E-07
TTC27 2 32853087 33046118 847 5.55E-07
RGS22 8 100973276 101118344 339 5.59E-07
CTCF 16 67596310 67673088 146 5.77E-07
METTL9 16 21610856 21668792 107 6.12E-07
NOP58 2 203130515 203168384 89 6.17E-07
TCF12 15 57210833 57580716 1181 6.34E-07
TMEM258 11 61556602 61560085 7 6.40E-07
LRP6 12 12268959 12419811 403 6.58E-07
ZNF462 9 109625378 109773807 331 7.61E-07
LRRC36 16 67360747 67419109 130 8.43E-07
SPAG17 1 118496288 118727848 528 1.04E-06
TCHH 1 152078793 152086556 16 1.05E-06
KIAA2012 2 202937978 202978327 147 1.14E-06
SUPT3H 6 44796469 45345670 1985 1.48E-06
CTNNB1 3 41240942 41281939 75 1.49E-06
PCGF3 4 699573 764428 328 1.83E-06
PLA2G15 16 68279247 68294961 38 1.86E-06
ELAVL4 1 50513686 50667540 294 1.90E-06
FAM175B 10 126490354 126525239 75 1.92E-06
ZNRF3 22 29279755 29453476 510 1.93E-06
FAM169B 15 98980391 99057611 281 2.17E-06
CENPT 16 67862060 67881361 33 2.24E-06
FYN 6 111982479 112194655 722 2.26E-06
ATP5SL 19 41937223 41945843 29 2.42E-06
REV3L 6 111620234 111804414 463 2.66E-06
MYRF 11 61520121 61555989 76 2.69E-06
RALY 20 32581732 32668067 157 2.70E-06
DLG5 10 79550549 79686348 492 2.73E-06

List of 13 X-chromosome genes:

Spoiler

GENE CHR START STOP NSNPS P
ITIH6 X 54775332 54824673 4 5.67E-05
KLF8 X 56258822 56314322 2 2.53E-08
FAAH2 X 57313110 57515629 8 9.96E-13
ARHGEF9 X 62854848 63005426 7 1.11E-11
MTMR8 X 63487961 63615333 4 1.12E-06
ZC4H2 X 64136250 64254593 3 5.32E-10
VSIG4 X 65241580 65259967 3 1.09E-35
HEPH X 65382433 65487231 5 1.16E-96
EDA2R X 65815479 65859140 2 5.13E-190
AR X 66763874 66944119 6 2.02E-269
OPHN1 X 67262186 67653299 41 4.25E-190
STARD8 X 67867511 67945684 12 1.56E-17
EDA X 68835911 69259322 40 5.54E-05

Some discussion from the paper:



Seems simple, right?

This is interesting:

The results of this study might help identify those at the greatest risk of hair loss and also potential genetic targets for intervention.

I wonder if they actually think that these genetic loci can be interfered with somehow to reverse or prevent the process. Or if they are talking about a future type of treatment that is at the moment quite unclear.

 

[abcdefg]

Each day I get a little more pessimistic on my view for male pattern baldness. If you find the genes and the risks associated with them so what? If we cant come up with a way to simply maintain hair what good is this genetic info? Your never going to genetically prevent male pattern baldness it would take 10 years to get a treatment through starting today, and the risks are just too unpredictable. Its not even worth trying.
Multiplying/growing hair through stem cells will be the cure someday and will probably happen before you ever untangle the genetic mess, or figure out how to intervene to alter/change the genetics. You will never be able to do that in our lifetimes
I guess I dont see the point in doing this versus trying to find a physical treatment that maintains/regrows hair. If you can tell someone they are screwed genetically what good does that really do?

 

[Trouse]

Each day I get a little more pessimistic on my view for male pattern baldness. If you find the genes and the risks associated with them so what? If we cant come up with a way to simply maintain hair what good is this genetic info? Your never going to genetically prevent male pattern baldness it would take 10 years to get a treatment through starting today, and the risks are just too unpredictable. Its not even worth trying.
Multiplying/growing hair through stem cells will be the cure someday and will probably happen before you ever untangle the genetic mess, or figure out how to intervene to alter/change the genetics. You will never be able to do that in our lifetimes
I guess I dont see the point in doing this versus trying to find a physical treatment that maintains/regrows hair. If you can tell someone they are screwed genetically what good does that really do?

If you have some free time, look up gene editing, specifically CRISPR. They're making massive strides in identifying the genes that cause certain conditions but also figuring out how to theoretically substitute these parts of the genome with a different coding. It sounds like science fiction but it's happening in labs right now. The implications will go beyond hair loss too, they could potentially substitute out the genetic coding responsible for Down's syndrome and the like. I'd say it's a lock that this happens in our lifetime, maybe even within 20 years or so.

 

[Grasshüpfer]

So we CRISPR ourselves at home at OPHN1 and ZC4H2 and end up mentally retarded.

I wonder if you can combine this data with an analysis of donor zone hair, to narrow it down even more.

 

[Armando Jose]

Interesting study, where we can see that common baldness is not a issue of only a few genes, regulating androgens, but it is multifactorial.

BTW I bet if only they could measure the thickness and density of scalp hair, it is possible a good surprise-

 

[InBeforeTheCure]

Each day I get a little more pessimistic on my view for male pattern baldness. If you find the genes and the risks associated with them so what? If we cant come up with a way to simply maintain hair what good is this genetic info? Your never going to genetically prevent male pattern baldness it would take 10 years to get a treatment through starting today, and the risks are just too unpredictable. Its not even worth trying.
Multiplying/growing hair through stem cells will be the cure someday and will probably happen before you ever untangle the genetic mess, or figure out how to intervene to alter/change the genetics. You will never be able to do that in our lifetimes
I guess I dont see the point in doing this versus trying to find a physical treatment that maintains/regrows hair. If you can tell someone they are screwed genetically what good does that really do?

This kind of mess is exactly what you see with other complex polygenic disorders. Probably it would be best to start by looking at pathways that these genes are part of. We can see there are a lot of genes involved in canonical Wnt signaling that show up in the GWAS -- WNT3, WNT6, WNT10A, LRP6, DKK2, CTNNB1, LGR4, RSPO2, ZNRF3, and others that may play a role in the Wnt pathway like IQGAP1 and of course AR itself. So deregulation of Wnt signaling contributes at least in part to development of Androgenetic Alopecia.

Keep in mind though when looking at this stuff that many genes in the list probably aren't located nearest to the functional variants they control. For example, there's a SNP within the MCM6 gene associated with lactose tolerance. However, it's not MCM6 that's the functional gene there, but the nearby LCT (lactase gene), and the SNP is just located in a regulatory region for the LCT gene.

One instance of this in our case may be the SNP in HDAC9. Regulatory elements within the HDAC9 sequence are known to control TWIST1 expression (source). TWIST1 is overexpressed in Androgenetic Alopecia according to Cotsarelis' microarray study and is known to affect hair growth (source). There will be many more like this, so it makes it even harder.

Treatments much better than today's conventional treatments are possible -- we know this because of the results people get with feminizing regimens involving cyproterone acetate and estrogen and so on. But yes, you're probably right that a good cell-based solution (hopefully Tsuji within the next seven years) will come before any kind of miraculous chemical treatment. Maintaining hair genetically is easy in theory though -- knock out AR and that's all you need. And in practice most people maintain fine with anti-androgens.

 

[trunks]

Additionaly, in Supplementary Table 4 this study shows no positive corelation between male pattern baldness and other diseases, traits, cancers etc

 

[InBeforeTheCure]

I've gone through the data and tried to pick out what I consider the most likely responsible gene for each region identified by the GWAS. There seem to be about 60 separate regions, give or take a few. I considered as more likely:

- genes which are closer to the GWAS hit, especially those within 200kb or so
- genes known to be involved in hair regulation
- genes known to interact with AR (such as coactivators)
- genes that interact with other candidate genes

An unbiased analysis with something like eQTL would be much better, but we don't have eQTL for hair follicle cell lines unfortunately. In a few cases I picked two genes in a region, and for many of them was clueless as to what the affected gene might be due to lack of the above characteristics. Of course, in some cases they may be acting on genes faaar away or even on another chromosome, so we would miss them anyway without something like eQTL. Some no doubt involve non-coding RNAs and/or uncharacterized genes as well. If you disagree with any of my guesses, let me know. Anyway, I put the list I came up with into STRING to visualize known interactions between them, which is much nicer than looking at a list.

I'll post a bunch of notes on this stuff some other time because there are some interesting little subnetworks, but for now I'm sure many of you recognize a lot of the genes in the region of high-connectivity.

The list of regions and guesses:

Chr Start End Guess
1 10535003 11107296 SRM? MTOR?
1 25071760 25291501 RUNX3
1 50513686 51425936 FAF1?
1 1.18E+08 1.2E+08 TBX15
1 1.52E+08 1.52E+08 TCHH
1 1.71E+08 1.71E+08 PRRX1
2 28113482 28561768 BRE?
2 31557188 33046118 SRD5A2
2 43457975 43823185 THADA??? PLEKHH2???
2 2.03E+08 2.03E+08 Most likely BMPR2…Possibly FZD7
2 2.2E+08 2.2E+08 WNT10A
2 2.23E+08 2.23E+08 PAX3
2 2.4E+08 2.4E+08 TWIST2
3 11314010 11599139 ATG7
3 41240942 41281939 CTNNB1
3 1.26E+08 1.26E+08 KLF15???
3 1.39E+08 1.39E+08 PRR23A???
3 1.41E+08 1.41E+08 RASA2???
3 1.52E+08 1.52E+08 SUCNR1???
4 699573 764428 PCGF3?
4 81187742 81884910 FGF5
4 1.08E+08 1.08E+08 DKK2
5 1.22E+08 1.23E+08 PPIC???
5 1.58E+08 1.59E+08 EBF1?
6 391739 411443 IRF4
6 9607550 9977826 TFAP2A
6 44796469 45345670 RUNX2
6 1.11E+08 1.12E+08 FYN
6 1.26E+08 1.27E+08 NCOA7?
6 1.31E+08 1.31E+08 AKAP7
7 536895 559481 PDGFA
7 18126572 19036993 TWIST1
7 69063905 70257885 AUTS2?
8 1.01E+08 1.01E+08 VPS13B?
8 1.09E+08 1.09E+08 RSPO2
8 1.16E+08 1.17E+08 TRPS1
9 1.1E+08 1.1E+08 ZNF462
10 77542519 78317130 ZNF503???
10 79550549 79686348 DLG5?
10 1.26E+08 1.27E+08 FAM53B???
11 27387508 27494334 LGR4
11 61520121 61634825 FADS2???
12 12268959 12419811 LRP6
12 26348269 28124916 SSPN
12 1.08E+08 1.08E+08 PRDM4? BTBD11?
15 57210833 57580716 TCF12
15 90931473 91045475 IQGAP1
15 98980391 99057611 IGF1R
16 21610856 21668792 METTL9??? IGFS6???
16 67360747 68294961 RANBP10?
16 89773541 89787394 VPS9D1??? MC1R???
17 43209967 44896082 WNT3
18 42260138 43263072 SETBP1
19 41860322 41945843 TGFB1
20 21686297 21696620 PAX1
20 32581732 33099197 AHCY???
20 39657462 39928739 PLCG1
22 29279755 29453476 ZNRF3
X 54775332 57515629 FAAH2???
X 62854848 69259322 AR

 

[InBeforeTheCure]

After looking more closely, I've updated the list of what IMO are the best candidate genes at each of the loci identified in this GWAS.

Chr Start End Gene
1 10535003 11107296 TARDBP? SRM? MTOR? UBIAD1?
1 25071760 25291501 RUNX3
1 50513686 51425936 FAF1?
1 1.18E+08 1.2E+08 TBX15
1 1.52E+08 1.52E+08 TCHH
1 1.71E+08 1.71E+08 PRRX1
2 28113482 28561768 FOSL2?
2 31557188 33046118 SRD5A2
2 43457975 43823185 PLEKHH2?
2 2.03E+08 2.03E+08 Most likely BMPR2…Possibly FZD7
2 2.2E+08 2.2E+08 WNT10A
2 2.23E+08 2.23E+08 PAX3
2 2.4E+08 2.4E+08 TWIST2
3 11314010 11599139 ATG7
3 41240942 41281939 CTNNB1
3 1.26E+08 1.26E+08 KLF15???
3 1.39E+08 1.39E+08 COPB2?
3 1.41E+08 1.41E+08 RASA2? RNF7?
3 1.52E+08 1.52E+08 MBNL1
4 699573 764428 PCGF3
4 81187742 81884910 FGF5
4 1.08E+08 1.08E+08 DKK2
5 1.22E+08 1.23E+08 PPIC??? SNX24???
5 1.58E+08 1.59E+08 EBF1?
6 391739 411443 IRF4
6 9607550 9977826 TFAP2A
6 44796469 45345670 RUNX2
6 1.11E+08 1.12E+08 FYN
6 1.26E+08 1.27E+08 NCOA7?
6 1.31E+08 1.31E+08 AKAP7
7 536895 559481 PDGFA
7 18126572 19036993 TWIST1
7 69063905 70257885 AUTS2
8 1.01E+08 1.01E+08 VPS13B???
8 1.09E+08 1.09E+08 RSPO2
8 1.16E+08 1.17E+08 TRPS1
9 1.1E+08 1.1E+08 ZNF462?
10 77542519 78317130 C10orf11?
10 79550549 79686348 DLG5?
10 1.26E+08 1.27E+08 ZRANB1?
11 27387508 27494334 LGR4
11 61520121 61634825 FADS2???
12 12268959 12419811 LRP6
12 26348269 28124916 SSPN
12 1.08E+08 1.08E+08 ASCL4?
15 57210833 57580716 TCF12
15 90931473 91045475 IQGAP1
15 98980391 99057611 IGF1R
16 21610856 21668792 IGSF6???
16 67360747 68294961 RANBP10?
16 89773541 89787394 MC1R???
17 43209967 44302740 MAPT
17 44668035 44896082 WNT3
18 42260138 43263072 SETBP1
19 41860322 41945843 TGFB1
20 21686297 21696620 PAX1
20 32581732 33099197 ASIP (Agouti)
20 39657462 39928739 PLCG1
22 29279755 29453476 ZNRF3
X 54775332 57515629 FAAH2???
X 62854848 69259322 AR

String-DB view:

There are some interesting "subnetworks" possible here...

Wnt Pathway Subnetwork (WNT3, WNT10A, LRP6, IQGAP1, RSPO2, DKK2, CTNNB1, ZRANB1, LGR4, ZNRF3, maybe FZD7)

The most obvious one. String-DB almost draws a full pathway diagram like this one.

Figure 2. LGR4-Wnt/β-catenin signaling pathway. In the absence of Rspos, membrane E3 ubiquitin ligases ZNRF3/RNF43 ubiquitinates the (Frizzled) FZD receptor for degradation, Wnt signaling activity is blunted. Cytoplasmic β-catenin is degradated by the β-catenin destruction complex, leading to no β-catenin complex formation with T-cell transcription factor (Tcf) and subsequent silence in active transcriptional response. In the presence of Rspos, simultaneous binding of LGR4 and ZNRF3 inhibits the ubiquitination of FZD receptor, meanwhile, LGR4 recruits IQGAP1 and increases its affinity to DVL, leading to the formation of supercomplex with Wnt signalosome. This allows β-catenin accumulation in cytoplasm, followed by translocation into the nucleus and activation of TCF target genes. LGR4, leucine-rich repeat-containing G protein-coupled receptors 4; ZNRF3, zinc and ring finger 3; FZD, Frizzled class receptor; Rspos, R-spondins; LRP5/6, low-density lipoprotein receptor-related protein 5/6; Ubi, ubiquitination; DVL, disheveled. (Mulholland et al., 2015)

The scaffold protein IQGAP1 also plays a role in shuttling beta-catenin to the nucleus (Shibuya et al., 2013). IQGAP1 is overexpressed in A.G.A. DPCs according to a proteomics analysis (Moon et al., 2013) and is downregulated by estrogen in HFs (pg. 108-109 of this dissertation).

RSPO2, the particular R-spondin associated with A.G.A., is expressed only in dermal papilla cells according to Rendl's Hair-Gel site. Therefore, it could be that dermal Wnt signaling is more important in A.G.A. than epithelial. This wouldn't be particularly surprising, since DPCs would of course be the site of cross-talk between AR and beta-catenin, which is enhanced in DPCs taken from bald subjects (Kitagawa et al., 2009).

Top row shows co-immunoprecipitation of beta-catenin and AR (basically, how often beta-catenin is found in a complex with AR) in untreated cells (-), cells treated only with DHT (D), cells treated with Wnt3a (W), and cells treated with both Wnt3a and DHT (WD). Bottom row is same for a fullhead.

Another one showing that AR can also inhibit Wnt signaling through upregulation of GSK3beta: (Leiros et al., 2012)

This shows profound inhibition of epithelial stem cell differentiation by DHT, which was reversed by lithium chloride, a GSK3beta inhibitor. In Fig 3(b), the HF stem cells maybe even hyperproliferate somewhat with DHT + LiCl rather than with LiCl alone.

Another study (Soma et al., 2005) finds that versican, a target gene of beta-catenin in DPCs, is virtually absent in A.G.A. vellus hairs.

Dermal beta-catenin is required for HFs to go into normal anagen (Morgan et al., 2010), and Wnt ligands from a subpopulation of DPCs (which express CD133) enlarges the dermal papilla during anagen (Zhou et al., 2016).

TWIST1/TWIST2/TCF12/RUNX2/RUNX3/TGFB1/BMPR2/maybe FOSL2 Subnetwork

This is a really interesting cluster containing several genes that play a central role in differentiation of mesenchymal cells into bones and so on, and most of these are known to have an effect on hair growth as well. Curiously enough, estrogen has been shown in HFs to modulate expression of FOSL2 itself as well as SPP1 (osteopontin), decorin, and FGFR2, which are targets of this network in mesenchymal cells (see pg. 108-109 of that dissertation). The correlate to mesenchymal stem cells in the dermis would probably be skin-derived precursor cells (SKPs). These are quite similar to neural crest cells and can differentiate into dermal fibroblasts, dermal papilla cells, adipocytes, blood vessels, and more. In fact, the dermal papilla itself is a niche for these cells. Some interesting excerpts from this paper (Biernaskie et al., 2010):

These cells, termed SKPs for SKin-derived Precursors, displayed properties similar to embryonic neural crest precursors, and within facial dermis were derived from the neural crest (Fernandes et al., 2004). Interestingly, the dermal papillae (DP) of hair follicles appear to comprise one niche for SKPs, based upon coincident patterns of gene expression, and upon the finding that cells with properties of SKPs can be cultured from adult whisker follicle papillae (Fernandes et al., 2004; Hunt et al., 2007; Joannides et al., 2004).

Finally, we asked whether SKPs hair follicle integration was modified by skin wounding. Neonatal murine YFP+ SKPs were transplanted adjacent to punch wounds on NOD/SCID mouse back skin. 3–4 weeks later, many transplanted cells were present within the scar, where they expressed fibroblast-specific antigen, collagen type 1, fibronectin and the myofibroblast protein α-sma (Fig. 4P–R; Fig. S4F,G) (16% expressed high α-sma). Interestingly, transplanted cells were also present in DP and DS of immature-appearing hair follicles (Fig. 4S,T), with the DP cells appropriately expressing versican (Fig. 4T) and p75NTR (data not shown), suggesting that SKPs contribute to new follicle formation in wounded skin.

Interestingly, adult rat GFP+ SKPs were highly enriched for hair follicle inductive ability (Fig. 5E,F), generating follicles where the entire DS and DP was comprised of genetically-tagged cells (Fig. 5C,D). Neonatal YFP-expressing murine SKPs also induced follicle formation (data not shown).

We next performed in vivo experiments, taking advantage of the finding that the size of the DP determines follicle size (Ibrahim and Wright, 1982). GFP+ adult rat SKPs were injected into depilated adult NOD/SCID mouse back skin and analyzed after 8 weeks. Many transplanted cells differentiated into interfollicular dermal fibroblasts (Fig. 5G), and many comprised the entire DP and DS of correctly-oriented follicles (Fig. 5G,H). Remarkably, relative to endogenous murine hairs, hairs induced by rat SKPs were longer (10.41 mm ± 0.23 versus 7.96 mm ± 0.11; p < 0.0001) and had increased follicle bulb diameter (107.24 μm ± 4.99 versus 82.27 μm ± 2.51; p <0.01) and hair fiber width (49.26 μm ± 0.87 versus 44.60 μm ± 0.83; p < 0.001) (n=8, with 3 animals quantified) (Fig. 5I,J). Although many of these follicles were in anagen (Fig. 5H), some were in catagen/telogen phase (Fig. 5K), indicating that follicle-associated SKPs cycle with their newly-induced hairs.

To confirm that rat SKPs induced larger follicles, we performed patch assays. Adult rat SKPs instructed mouse epidermal cells to generate larger follicles than did mouse dermal cells, with an almost 2-fold increase in bulb diameter (Fig. 5L–N). Confocal microscopy demonstrated that the increased rat SKP follicle size correlated with almost 4 times more NCAM+ DP cells (Fig. 5O–Q) (88% of these cells were GFP+).

Clearly, SKPs are attracted to cells that are similar, as seen in patch assays where single dissociated SKP cells aggregated to form structures that nucleated hair follicle formation. While the relevant attractive signal is unknown, evidence that it is cell-intrinsic comes from our data showing that more rat than mouse cells aggregate to form the DP, even within the same tissue environment.

Biernaskie et al., 2014 found that dermal sheath cells could generate SKPs. Since beta-catenin is important for dermal fibroblast aggregation (versican has something to do with this), maybe in adults dermal Wnt signaling it's also important for bringing in new DPCs from the dermal sheath during anagen.

But anyway, here's a little scheme I made of this Twist/Runx/etc. network:

Keep in mind that target genes of transcription factors in mesenchymal cells might not be the same in dermal cells of skin/hair follicles.

(continued in next post)

 

[InBeforeTheCure]

Runx2 and Twist are major transcription factors in regulating mesenchymal stem cell differentiation, with Twist acting as an inhibitor of Runx2 function.

Runx2 is necessary and sufficient for osteoblast differentiation, yet its expression precedes the appearance of osteoblasts by 4 days. Here we show that Twist proteins transiently inhibit Runx2 function during skeletogenesis. Twist-1 and -2 are expressed in Runx2-expressing cells throughout the skeleton early during development, and osteoblast-specific gene expression occurs only after their expression decreases. Double heterozygotes for Twist-1 and Runx2 deletion have none of the skull abnormalities observed in Runx2+/− mice, a Twist-2 null background rescues the clavicle phenotype of Runx2+/− mice, and Twist-1 or -2 deficiency leads to premature osteoblast differentiation. Furthermore, Twist-1 overexpression inhibits osteoblast differentiation without affecting Runx2 expression. Twist proteins' antiosteogenic function is mediated by a novel domain, the Twist box, which interacts with the Runx2 DNA binding domain to inhibit its function. In vivo mutagenesis confirms the antiosteogenic function of the Twist box. Thus, relief of inhibition by Twist proteins is a mandatory event precluding osteoblast differentiation.

(Karsenty et al., 2004)

Twist can form either homodimers or heterodimers with E-proteins such as Tcf3 or Tcf12 (a GWAS hit for A.G.A.), and this balance is regulated by Id proteins. Typically, BMP upregulates Id, while TGF-beta can either upregulate or downregulate Id depending on context. BMPR2 and TGFB1 are two A.G.A. GWAS hits.

Saethre-Chotzen syndrome is associated with haploinsufficiency of the basic-helix–loop–helix (bHLH) transcription factor TWIST1 and is characterized by premature closure of the cranial sutures, termed craniosynostosis; however, the mechanisms underlying this defect are unclear. Twist1 has been shown to play both positive and negative roles in mesenchymal specification and differentiation, and here we show that the activity of Twist1 is dependent on its dimer partner. Twist1 forms both homodimers (T/T) and heterodimers with E2A E proteins (T/E) and the relative level of Twist1 to the HLH inhibitor Id proteins determines which dimer forms. On the basis of the expression patterns of Twist1 and Id1 within the cranial sutures, we hypothesized that Twist1 forms homodimers in the osteogenic fronts and T/E heterodimers in the mid-sutures. In support of this hypothesis, we have found that genes regulated by T/T homodimers, such as FGFR2 and periostin, are expressed in the osteogenic fronts, whereas genes regulated by T/E heterodimers, such as thrombospondin-1, are expressed in the mid-sutures. The ratio between these dimers is altered in the sutures of Twist1+/− mice, favoring an increase in homodimers and an expansion of the osteogenic fronts. Of interest, the T/T to T/E ratio is greater in the coronal versus the sagittal suture, and this finding may contribute to making the coronal suture more susceptible to fusion due to TWIST haploinsufficiency. Importantly, we were able to inhibit suture fusion in Twist1+/− mice by modulating the balance between these dimers toward T/E formation, by either increasing the expression of E2A E12 or by decreasing Id expression. Therefore, we have identified dimer partner selection as an important mediator of Twist1 function and provide a mechanistic understanding of craniosynostosis due to TWIST haploinsufficiency. Developmental Dynamics 235:1345–1357, 2006. © 2006 Wiley-Liss, Inc.

(Spicer et al., 2006)

Twist can also act as a negative feedback regulator of NF-kB activity – activated NF-kB upregulates Twist expression, Twist binds to the RELA (p65) subunit of NF-kB and inhibits expression of NF-kB target genes (Olson et al., 2003). Twist is also upregulated by Wnt3a in mouse DPCs (Figure 2(c)).

Runx2 and AR bind directly to each other and are for the most part mutually antagonistic. However, in prostate cancer cell lines, while most AR target genes are downregulated by Runx2-AR binding (as well as Runx2 target genes), Runx2 enhances AR transactivation of a small subset of AR target genes (Little et al., 2014).

As for known connections to hair follicle biology...

Inducible Knockout of Twist1 in Young and Adult Mice Prolongs Hair Growth Cycle and Has Mild Effects on General Health, Supporting Twist1 as a Preferential Cancer Target

IMPAIRED SKIN AND HAIR FOLLICLE DEVELOPMENT IN RUNX2 DEFICIENT MICE

Runx3 is involved in hair shape determination

BMP signaling in dermal papilla cells is required for their hair follicle-inductive properties

DHT has been shown to stimulate TGF-beta1 expression in DPCs at atmospheric oxygen levels, but one study (Philpott et al., 2015) showed that at physiological oxygen levels, DHT actually inhibits TGF-beta1 expression. In vivo observations would therefore be very nice to have.

Growth Factor RTK Subnetwork (PDGFA, IGF1R, FGF5, FYN, PLCG1, RASA2, MTOR, IQGAP1)

All three growth factor receptor tyrosine kinases (RTK) pathways implicated here have known roles in HF biology.

PDGFA – ligand for platelet derived growth factor receptor (PDGFR) - PDGF isoforms induce and maintain anagen phase of murine hair follicles

IGF1R (insulin-like growth factor 1 receptor) - various papers out there

FGF5 (fibroblast growth factor 5) - FGF5 is a crucial regulator of hair length in humans

Downstream effectors of RTKs:

Fyn – a Src-like kinase often activated downstream of growth factor RTKs which plays a role in cell differentiation and migration, among other things

PLCG1 (phospholipase C gamma-1) – downstream effector of these three receptors. Induces calcium ion release from the endoplasmic reticulum to the cytoplasm, activates PKC. Both are known to affect HF function.

Two major pathways, often activated by RTKs, which drive cell cycle progression and proliferation are the Ras/Raf/MEK/ERK pathway and the PI3K/Akt/mTOR pathway. A couple candidates among these two pathways:

RASA2 (RAS P21 Protein Activator 2) – inhibits Ras

MTOR (mammalian target of rapamycin)

Mammalian target of rapamycin complex 1 (mTORC1) may modulate the timing of anagen entry in mouse hair follicles

mTOR signaling promotes stem cell activation via counterbalancing BMP-mediated suppression during hair regeneration

The dark side...

mTOR Mediates Wnt-Induced Epidermal Stem Cell Exhaustion and Aging

Epidermal integrity is a complex process established during embryogenesis and maintained throughout the organism lifespan by epithelial stem cells. Although Wnt regulates normal epithelial stem cell renewal, aberrant Wnt signaling can contribute to cancerous growth. Here, we explored the consequences of persistent expressing Wnt1 in an epidermal compartment that includes the epithelial stem cells. Surprisingly, Wnt caused the rapid growth of the hair follicles, but this was followed by epithelial cell senescence, disappearance of the epidermal stem cell compartment, and progressive hair loss. Although Wnt1 induced the activation of beta-catenin and the mTOR pathway, both hair follicle hyperproliferation and stem cell exhaustion were strictly dependent on mTOR function. These findings suggest that whereas activation of beta-catenin contributes to tumor growth, epithelial stem cells may be endowed with a protective mechanism that results in cell senescence upon the persistent stimulation of proliferative pathways that activate mTOR, ultimately suppressing tumor formation.

^^^ These mice are sort of a partial model of hypotrichosis simplex, a rare disorder characterized by progressive HF miniaturization and baldness, usually beginning around the age of five. In hypotrichosis simplex, Wnt signaling is overactive because of a missense mutation in APCDD1, a Wnt negative feedback regulator (Christiano et al., 2010).

IQGAP1 also plays an important role downstream of RTK signaling. For example, IQGAP1 serves as a scaffold for Raf, MEK, and ERK. Expression of IQGAP1 may have a biphasic effect on Ras/Raf/MEK/ERK pathway activity.

(Stuart and Sellers, 2013)

IQGAP1 also interacts with Rac1 and Cdc42, common downstream targets of RTKs which regulate the cytoskeleton and cell migration.

Some possible smaller scale interactions...

ASIP (Agouti Signaling Peptide) and TBX15 + detour into adipocytes

Many members of the animal kingdom display coat or skin color differences along their dorsoventral axis. To determine the mechanisms that control regional differences in pigmentation, we have studied how a classical mouse mutation, droopy ear (deH), affects dorsoventral skin characteristics, especially those under control of the Agouti gene. Mice carrying the Agouti allele black-and-tan (at) normally have a sharp boundary between dorsal black hair and yellow ventral hair; the deH mutation raises the pigmentation boundary, producing an apparent dorsal-to-ventral transformation. We identify a 216 kb deletion in deH that removes all but the first exon of the Tbx15 gene, whose embryonic expression in developing mesenchyme correlates with pigmentary and skeletal malformations observed in deH/deH animals. Construction of a targeted allele of Tbx15 confirmed that the deH phenotype was caused by Tbx15 loss of function. Early embryonic expression of Tbx15 in dorsal mesenchyme is complementary to Agouti expression in ventral mesenchyme; in the absence of Tbx15, expression of Agouti in both embryos and postnatal animals is displaced dorsally. Transplantation experiments demonstrate that positional identity of the skin with regard to dorsoventral pigmentation differences is acquired by E12.5, which is shortly after early embryonic expression of Tbx15. Fate-mapping studies show that the dorsoventral pigmentation boundary is not in register with a previously identified dermal cell lineage boundary, but rather with the limb dorsoventral boundary. Embryonic expression of Tbx15 in dorsolateral mesenchyme provides an instructional cue required to establish the future positional identity of dorsal dermis. These findings represent a novel role for T-box gene action in embryonic development, identify a previously unappreciated aspect of dorsoventral patterning that is widely represented in furred mammals, and provide insight into the mechanisms that underlie region-specific differences in body morphology.

(Candille et al., 2004)

Mouse on the left is standard Agouti "black-and-tan" variant, on the right is Agouti black-and-tan plus Tbx15 loss of function. Agouti is secreted by dermal papilla cells and induces melanocytes to switch from producing eumelanin to producing pheomelanin through its interaction with MC1R, hence the yellow hair. Agouti is also known to upregulate expression of PPAR-gamma in adipocytes (Mynatt and Stephens, 2001), which play a role in epithelial HF stem cell activation (Festa et al., 2011) by secreting PDGFA. Mice treated with BADGE (a PPAR-gamma antagonist) can't go into anagen. Also notice how knockout of EBF1, a GWAS hit for A.G.A. in multiple studies, blocks differentiation into adipocyte precursors (from SKPs?) and also prevents follicles from regenerating.

Azip interferes with CEBP function, BTW. Therefore, the differentiation line could be something like this:

SKP + (at least EBF1) -> adipocyte precursor + (at least PPAR-gamma) -> preadipocyte + (at least CEBP) -> mature adipocyte

(continued in next post)

 

[InBeforeTheCure]

Genes Potentially Affecting Androgen Metabolism

SRD5A2 – 5-alpha-reductase type II, A.G.A. doesn't happen without it. SRD5A2 expression is higher in DPCs from bald scalp than in non-bald occipital DPCs.

(this is from Moon et al.)

UBIAD1 – Although the most distant of the candidate genes near the Chr1 locus, UBIAD1 (also called TERE1) is interesting because of its effects on androgen metabolism and common loss of expression in castration-resistant prostate cancer. (Fredericks et al., 2013)

^^^ If the same kind of pathway is at work in skin, maybe Vitamin K-2 analogs would be somewhat useful for A.G.A., who knows?

AR Regulation

AR – androgen receptor, A.G.A. doesn't happen without it. AR expression is higher in bald DPCs than in non-bald occipital DPCs.

(this is from Moon et al.)

RANBP10 – known AR coactivator (Harada et al., 2008)

MBNL1 and Myotonic Dystrophy

I came across a reference to a condition called myotonic dystrophy, and curiously enough, premature A.G.A. is very common in these people.

(Ralph Trueb, "The Difficult Hair Loss Patient", pg. 76)

Three cases of androgen-dependent disease associated with myotonic dystrophy:

Three cases of androgen-dependent disease in females with myotonic dystrophy are described. Serum androgens in individuals affected by myotonic dystrophy are known to be lower on average than in normal controls. Despite this these three females developed diseases that are androgen dependent, including acne, hidradenitis suppurativa, androgenetic alopecia and keratosis pilaris. These cases support the hypothesis that the peripheral response to androgens rather than absolute circulating levels of androgens is important in androgen-dependent conditions.

In myotonic dystrophy type 1 (the more severe form), the RNA-binding protein MBNL1 (musclebind like splicing regulator 1) is sequestered. This loss of function results in inappropriate embryonic-like splice patterns and failure of cells to differentiate properly (Lee and Cooper, 2013). A SNP associated with A.G.A., being about 300kb from the MBNL1, is somewhat distant but still well within the normal range for regulatory elements. Because of the myotonic dystrophy connection, I consider it the most likely candidate.

MBNL1 RIP target RNAs were also analysed by Gene Ontology biological networks and there was a clear enrichment in differentiation and developmental processes similar to the total RNAseq gene expression profile described earlier. These processes included vasculature development, regulation of development, cardiovascular system development, regulation of cell migration, tube development and epithelial-to-mesenchymal transition, in addition to strong enrichment in signatures of late mesoderm-associated genes. These MBNL1-bound transcripts included SRF, Twist1, FoxO3, Runx1, Cxcl12 and Il6st, which were all validated and quantified by RT–PCR here (Fig. 4e and Supplementary Table 2).

(Davis et al., 2015)

^^^ Genes involved in regulation of development and regulation of cell migration are a common theme in both the GWAS and in a list of genes affected by estrogen – perhaps the most potent reverser of A.G.A. – in hair follicles (again see the dissertation, pg. 108-109). Speaking of which, I put both the GWAS list and the estrogen list from that dissertation into WebGestalt for WikiPathways enrichment. The GWAS list was enriched for 42 pathways at p < 0.05, and the estrogen list for 22 pathways. Of the 22 pathways in the estrogen list, 14 pathways (63.6 percent) were also in the GWAS list. Given there are about 800 pathways in the WikiPathways database, this is quite a significant overlap. I'll admit that the estrogen list itself influenced me to pick FOSL2 for the GWAS list, but only one pathway in the WikiPathways database, "corticotropin-releasing hormone", contains it, and that one does show up in both lists. Anyway, these were the 14 pathways enriched for both the GWAS list and the estrogen list:

Focal Adhesion
EGF-EGFR Signaling Pathway
Muscle cell TarBase
Signaling Pathways in Glioblastoma
Corticotropin-releasing hormone
Regulation of Actin Cytoskeleton
Lymphocyte TarBase
TGF Beta Signaling Pathway
Endochondral Ossification
Androgen receptor signaling pathway
DNA damage response (only ATM dependent)
Senescence and Autophagy
Neural Crest Differentiation
MAPK signaling pathway

This myotonic dystrophy thing fascinates me though. It makes me wonder how much alternative splicing of genes involved in development are responsible for A.G.A. TARDBP, the closest characterized gene to that tricky Chr1 locus, is also an RNA splicing factor.

Structural Proteins

TCHH – trichohyalin, a structural protein of the inner root sheath that confers mechanical strength to hair. This is a missense mutation, also associated with straight vs. curly hair (Medland et al., 2009).

SSPN – sarcospan

Other Development-Related Genes

PAX1 – The second most significantly associated gene with A.G.A. after AR, expressed in DPCs. Often a hedgehog target gene involved in patterning of mesenchymal cell lineages. The same haploblock associated with A.G.A. is also associated with nose width (Adhikari et al., 2016) and inversely associated with specifically female idiopathic scoliosis but not with male idiopathic scoliosis (Wise et al. 2015).

PRRX1 – homeobox gene expressed in DPCs

TFAP2A – encodes the transcription factor AP-2alpha. Possibly involved in hair follicle remodeling (Panteleyev et al., 2003)

TRPS1 – DPC signature gene. Loss of function results in trichorhinophalangeal syndrome (TRPS), which includes hair loss. In one Japanese woman with TRPS, Stat3, Sox9, and beta-catenin were highly upregulated (Shibata et al., 2014). Another study (Christiano et al., 2012) showed that Trps1 inhibits Sox9 expression in mice. You could maybe put this in the Twist/Runx category, since Trps1 interacts with Runx2 and inhibits its activity (Lee et al., 2008).

Other References
SRM – Spermidine Promotes Human Hair Growth and Is a Novel Modulator of Human Epithelial Stem Cell Functions

ATG7 – The significant role of autophagy in the granular layer in normal skin differentiation and hair growth

 

[Armando Jose]

InBeforeTheCure,
are you working in a review of genes in alopecia?
Good luck

 

[Beowulf]

At a risk of sounding naive, could one use gene therapy such as CRISPR to destroy all the AR receptors in the scalp?

 

[InBeforeTheCure]

InBeforeTheCure,
are you working in a review of genes in alopecia?
Good luck

No Armando, I'm just speculating on these here internet forums.

At a risk of sounding naive, could one use gene therapy such as CRISPR to destroy all the AR receptors in the scalp?

Yeah, you could potentially use something like adeno-associated virus carrying a shRNA to knockdown AR -- something like this. You could even design it so that it turns on or off depending on whether you apply a certain chemical to your head.

 

[Grasshüpfer]

So it's possible to restict the virus to a specific area in the body, by controlling it through a chemical? That is insane...

Asked super naive again: What is the technical holdup, exept of the ethical problem of editing genes in living humans for cosmetic reasons?

 

[InBeforeTheCure]

So it's possible to restict the virus to a specific area in the body, by controlling it through a chemical? That is insane...

Yeah, and you can also design it so the gene is only activated in a specific cell type (for example, adipocytes), which is a trick often used in research to find out what a particular gene does in a particular cell type.

Asked super naive again: What is the technical holdup, exept of the ethical problem of editing genes in living humans for cosmetic reasons?

I'm not really familiar with how development of gene therapy is going overall and what the hurdles are. Maybe someone like @Swoop could give a good answer to that. AFAIK though, gene therapy is already approved for a couple disorders, and it's expected to become much bigger in the coming years.

 

[Swoop]

I'm not really familiar with how development of gene therapy is going overall and what the hurdles are. Maybe someone like @Swoop could give a good answer to that. AFAIK though, gene therapy is already approved for a couple disorders, and it's expected to become much bigger in the coming years.

First of all very impressive work!

Regarding the technical holdups I have no clue. I'm not really knowledgeable on this stuff. From what I have read (targeted) delivery and efficiency is still a problem.

There is already a drug running clinical trials for the androgen receptor though, for prostate cancer.

- ISIS-ARRx is a generation 2.5 antisense drug designed to inhibit the production of AR for the treatment of patients with prostate cancer. Because ISIS-ARRx can inhibit the production of all known forms of AR, including variants of the AR gene, this drug has the potential to be an effective treatment for all stages of prostate cancer, including prostate cancer patients who are resistant to current therapies.

 

[Beowulf]

Yeah, you could potentially use something like adeno-associated virus carrying a shRNA to knockdown AR -- something like this. You could even design it so that it turns on or off depending on whether you apply a certain chemical to your head.

Yeah, and you can also design it so the gene is only activated in a specific cell type (for example, adipocytes), which is a trick often used in research to find out what a particular gene does in a particular cell type.

So then you could design it so it wouldn't interfere with AR in the brain, and then only apply the chemical to the scalp, and since AR is stopped at the gene it won't create any more.

It looks like there have been a bit of research into whether one could stop the AR gene.


Prostate-targeted biodegradable nanoparticles loaded with androgen receptor silencing constructs eradicate xenograft tumors in mice.

"In this study, we utilized a biodegradable nanoparticle to deliver the therapeutic AR shRNA construct specifically to prostate cancer cells."

"A10-conjugation largely enhanced cellular uptake of nanoparticles in both cell culture- and xenograft-based models. The efficacy of AR shRNA encapsulated in nanoparticles on AR gene silencing was confirmed in PC-3/AR-derived xenografts in nude mice. The therapeutic property of A10-conjugated AR shRNA-loaded nanoparticles was evaluated in xenograft models with different prostate cancer cell lines: 22RV1, LAPC-4 and LNCaP. Upon two injections of the AR shRNA-loaded nanoparticles, rapid tumor regression was observed over 2 weeks. Consistent with previous reports, A10 aptamer conjugation significantly enhanced xenograft tumor regression compared with nonconjugated nanoparticles."

There is already a drug running clinical trials for the androgen receptor though, for prostate cancer.

It got renamed IONIS-AR-2.5Rx, apparently in January they announced that they were going to be releasing the details of the Phase 1/2 study sometime this year and their pipeline says they're doing Phase 2 trials. It looks promising, but I think the problem is that it's not selective.

Then again when it gets released someone could probably just turn it into a lotion, rub it into their scalp and see what happens.


Adeno-Associated Virus-Mediated Cancer Gene Therapy: Current Status

"However several problems about this gene delivery system should be addressed. Firstly, the effective packaging capacity of AAV is limited to 4.1 to 4.9kb [26], which restricts the transduction of larger genes. Secondly, antibody neutralization rises because of prior exposure of human beings with multiple AAV serotypes [27]. Thirdly, challenges with high-efficient transduction to specific cell populations remain in AAV mediated gene delivery system. Since these problems influenced the extended application of AAV based gene therapy, a variety of attempts to improve this vector have been carried out. Self-complementary AAV (scAAV) vectors can fold into double-stranded DNA (dsDNA) without DNA synthesis or base-pairing between multiple vector genomes [28] bypassing the conversion to dsDNA. Naturally, these vectors are more sufficient to transgene expression than normal AAV vectors. The clinical application of AAV vector was slowed down due to the limitation of packaging capacity of rAAV. Cotransduction of dual AAV vectors seems to be an alternative to solve this problem. Transgene expression cassettes are split into two, and each is packaged into a AAV vector. Then expression of full-length transgene is obtained via homologous recombination or viral inverted terminal repeat mediated recombination. Since low levels of pre-existing neutralizing antibodies significantly reduced the efficacy of therapeutic AAV gene delivery, modification of AAV capsid involved in interactions with host immunity has been an good idea to escape neutralization. Directed selection of AAV variants, “shielding” polymers, site-directed mutagenesis and directed evolution of AAV capsid made the neutralization escape of AAV based delivery system feasible"

Table 2 outlines possible uses of AAV vectors.

I don't really see why that's a problem for our purposes, but then again I barely understand this stuff at all.

 

[Beowulf]

Turns out the big problem is price. Alipogene tiparvovec from what I've seen is the first attempt at commercial AAV gene therapy, but it's only been used once because it costs $1,000,000. It's used to cure lipoprotein lipase deficiency which only appears in one in million and isn't life threatening, so it's no wonder no one bought it!

https://www.technologyreview.com/s/601165/the-worlds-most-expensive-medicine-is-a-bust/

https://en.wikipedia.org/wiki/Alipogene_tiparvovec

I guess it would be different in our case since heaps of people will want to buy it, so economies of scale should help.

You should probably write a whole academic article on it InBeforeTheCure and sell it to a company!