GWAS Identifies Three Susceptibility Loci for Trichilemmal Cysts

A genome-wide association study (GWAS) has identified three genetic loci that are associated with the development of trichilemmal cysts (TCs), which are keratin-filled nodules originating from the hair follicle. The study supports the previously proposed monoallelic two-hit model, where a germline variant in the PLCD1 gene (c.1379G>A, p.Ser460Leu) acts as a major risk allele for familial TCs. According to this model, a subsequent somatic mutation in the same allele of PLCD1 is necessary for the formation of each familial TC. This finding enhances the understanding of the genetic pathogenesis of hereditary trichilemmal cyst formation.