Hypotrichosis 13

A number sign (#) is used with this entry because of evidence that hypotrichosis-13 (HYPT13) is caused by heterozygous mutation in the KRT71 gene (608245) on chromosome 12q13. One such family has been reported.

For a discussion of genetic heterogeneity of hypotrichosis, see HYPT1 (605389).

Clinical Features

Fujimoto et al. (2012) reported a 3-generation Japanese family with woolly hair/hypotrichosis. The proband was a 5-year-old girl who had had tightly curled scalp hair since birth. The scalp hairs were short and stopped growing at a few inches, although there was no apparent hair shaft fragility; no follicular papules were present. The proband also showed reduced density of scalp hairs, eyebrows, and eyelashes. There were no dysmorphic features, and teeth, nails, and sweating were normal. Her father and paternal grandfather also had woolly hair and hypotrichosis; however, their symptoms gradually improved with age, resulting in only woolly hair with almost normal hair density. Under scanning electron microscopy, the proband's hair shafts frequently showed longitudinal grooves that were not seen in age-matched Japanese control hairs, suggesting abnormal hair growth.

Molecular Genetics

In a 3-generation Japanese family segregating autosomal dominant woolly hair/hypotrichosis, Fujimoto et al. (2012) sequenced 7 genes associated with nonsyndromic forms of woolly hair or autosomal dominant forms of hypotrichosis but identified no mutations. Subsequent analysis of 3 genes expressed in the inner root sheath revealed a heterozygous missense mutation in KRT71 (F141C; 608245.0001) that segregated with disease in the family and was not found in 200 Japanese controls.