Original Article
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Autosomal Recessive Hypotrichosis with Woolly Hair Caused by a Mutation in the Keratin 25 Gene Expressed in Hair Follicles

https://doi.org/10.1016/j.jid.2016.01.037Get rights and content
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Hypotrichosis is an abnormal condition characterized by decreased hair density and various defects in hair structure and growth patterns. In particular, in woolly hair, hypotrichosis is characterized by a tightly curled structure and abnormal growth. In this study, we present a detailed comparative examination of individuals affected by autosomal-recessive hypotrichosis (ARH), which distinguishes two types of ARH. Earlier, we demonstrated that exon 4 deletion in the lipase H gene caused an ARH (hypotrichosis 7; MIM: 604379) in populations of the Volga-Ural region of Russia. Screening for this mutation in all affected individuals revealed its presence only in the group with the hypotrichosis 7 phenotype. Other patients formed a separate group of woolly hair-associated ARH, with a homozygous missense mutation c.712G>T (p.Val238Leu) in a highly conserved position of type I keratin KRT25 (K25). Haplotype analysis indicated a founder effect. An expression study in the HaCaT cell line demonstrated a deleterious effect of the p.Val238Leu mutation on the formation of keratin intermediate filaments. Hence, we have identified a previously unreported missense mutation in the KRT25 gene causing ARH with woolly hair.

Abbreviations

ARH
autosomal-recessive hypotrichosis
HF
hair follicle
HS
hair shaft
IRS
inner root sheath
KIF
keratin intermediate filaments
KRT25
keratin 25 gene
KRT71
keratin 71 gene
KRT74
keratin 74 gene
LIPH
lipase H gene
Mut
p.Val238Leu mutant
Wt
wild-type
WH
woolly hair

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