Molecular epidemiology of pachyonychia congenita in the Israeli population.

Abstract

Pachyonychia congenita (PC) is a rare autosomal dominant disorder featuring palmoplantar keratoderma, nail dystrophy, oral leucokeratosis, pilosebaceous cysts and natal teeth. PC results from dominant mutations in one of five genes (KRT6A, KRT6B, KRT6C, KRT16, KRT17) encoding keratin proteins. To delineate the clinical and genetic features of PC in a series of Israeli patients. We used direct sequencing of genomic DNA, and also used cDNA sequencing where applicable. We collected clinical information and molecular data in a cohort of Israeli families diagnosed with PC (n=16). Most of the patients were Ashkenazi Jews and had a family history of PC. The most common clinical findings were painful focal plantar keratoderma (94%) accompanied by nail dystrophy (81%), pilosebaceous cysts (31%) and prenatal/natal teeth (13%). In contrast to the high prevalence of KRT6A mutations in other populations, we found that KRT16 mutations were the most common type among Israeli patients with PC (56%). Most (77%) of the Israeli patients with PC with KRT16 mutation carried the same variant (c.380G>A; p.R127H) and shared the same haplotype around the KRT16 locus, suggestive of a founder effect. The data gleaned from this study emphasizes the importance of population-specific tailored diagnostic strategies.