Why is hair kinky?

I saw this paper in Nature Genetics, Disruption of P2RY5, an orphan G protein-coupled receptor, underlies autosomal recessive woolly hair:

The genetic determinants of hair texture in humans are largely unknown. Several human syndromes exist in which woolly hair comprises a part of the phenotype; however, simple autosomal recessive inheritance of isolated woolly hair has only rarely been reported…In all cases, we discovered pathogenic mutations in P2RY5, which encodes a G protein-coupled receptor and is a nested gene residing within intron 17 of the retinoblastoma 1 (RB1) gene. P2RY5 is expressed in both Henle’s and Huxley’s layers of the inner root sheath of the hair follicle. Our findings indicate that disruption of P2RY5 underlies ARWH and, more broadly, uncover a new gene involved in determining hair texture in humans.

Disease loci can tell us a lot about the normal range of human variation; the blue-eye gene was originally implicated in a form of albinism. So I got curious and popped P2RY5 into Haplotter, which detects recent selection events. Here’s what I found….

Here’s iHS:

And H:

Looks like there’s some action going on here. We’re looking at Yoruba (YRI), European (CEU) and East Asian groups (ASN) if you didn’t know. Here’s the table which shows p-values in the genomic region around this locus:

Genes in the region

Gene ID	Name	Region	CEU	YRI	ASN
8803	SUCLA2	46314792 – 46373463	0.093768	0.011064	0.359281
55270	NUDT15	46409704 – 46419283	0.093768	0.005330	0.359281
29079	MED4	46448093 – 46467241	0.117392	0.015274	0.539616
9445	ITM2B	46602310 – 46634228	0.999955	0.300291	0.999954
5925	RB1	46675912 – 46854023	0.999955	0.021859	0.999954
10161	P2RY5	46783275 – 46787947	0.999955	0.021814	0.539616
1102	RCBTB2	46861100 – 46905317	0.999955	0.036685	0.539616
57105	CYSLTR2	47078952 – 47081499	0.541838	0.999955	0.999954
9206	RAD17P2	47415974 – 47418931	0.999955	0.225666	0.539616

I’ll let you figure out what’s going on with NUDT15….
Related: EDAR controls hair thickness.