A new type of pachyonychia congenita.

The document described two patients with a unique form of autosomal dominant ectodermal dysplasia characterized by thickened nails, similar to pachyonychia congenita, and severe generalized hypotrichosis, without other abnormalities. Histopathological examination revealed a reduced number of hair follicles in the scalp. Sequencing of keratins typically associated with pachyonychia congenita (Krt 6a, 6b, 16, and 17) did not show mutations, suggesting a new type of pachyonychia potentially caused by a mutation in a hard keratin.