These findings give further evidence that palmoplantar keratoderma of Vörner represents the same entity as palmoplantar keratoderma of Thost, which was recently re-evaluated in Thost's original family and shown to be caused by a similar mutation, R162 W, in the same segment of keratin 9.
It has recently been demonstrated that genetic defects in keratin genes cause a number of different skin disorders, including epidermolysis bullosa simplex (EBS), epidermolytic hyperkeratosis (EH), the EH form of epidermal nevi, epidermolytic and non-epidermolytic forms of palmoplantar keratoderma (EPPK and PPK) and pachyonychia congenita (PC).
Two different forms of palmoplantar keratoderma have recently been shown to be caused by mutations in the body site-specific keratin 9 gene and in the keratin 1 gene, respectively.
The palmoplantar keratoderma variant investigated in this study is thus genetically different from epidermolytic palmoplantar keratoderma, which recently has been shown to result from mutations in the gene for the type I keratin 9.