Nonsyndromic congenital nail disorder (NDNC) is rare and has been reported in only a small number of families. There is a variable expression of nail phenotypes among individuals. It has been identified that mutations in the RSPO4 and FZD6, components of the Wnt pathway, cause hypoplastic nail disorders. Hereditary leukonychia is caused by mutations in PLCD1. Defects in COL7A1 can cause heterogeneous clinical phenotypes extending from simple toe-nail dystrophy without skin fragility to typical dominant dystrophic epidermolysis bullosa.
