Two cases of severe congenital hypotrichosis caused by compound heterozygous mutations in the LSS gene

It has recently been shown that bi‐allelic mutations in the lanosterol synthase (LSS) gene, which was originally reported as a causative gene for congenital cataracts, underlie a non‐syndromic form of hypotrichosis. Furthermore, it has also been revealed that mutations in the LSS gene can cause syndromic forms of hypotrichosis. To date, however, clear genotype–phenotype correlations have not completely been characterized. In this study, we identified two Japanese patients who had severe congenital hypotrichosis without any other associated findings. Their scalp hairs were extremely short and thin, and were able to be plucked easily. Observation of the plucked hairs showed aberrantly‐miniaturized anagen hair follicles. Genetic analysis demonstrated that both patients carried bi‐allelic mutations in the LSS gene in a compound heterozygote state. Our findings further underscore the crucial roles of the LSS gene in hair follicle development and hair growth in humans.