['Nagashima-type palmoplantar keratosis (NPPK) is a distinct autosomal recessive genodermatosis characterized by diffuse transgressive palmoplantar keratoderma (PPK). Very recently, putative loss-of-function mutations in SERPINB7, which encodes a member of the serine protease inhibitor superfamily and is abundantly expressed in the epidermis, have been identified as a cause of NPPK.', 'To confirm further the role of SERPINB7 mutations in the pathogenesis of NPPK.', 'We analysed 10 Japanese families with NPPK using Sanger and/or whole-exome sequencing.', 'We identified one novel and three recurrent null mutations in SERPINB7. In all the families, the NPPK trait was inherited in an autosomal recessive manner; in one of the families, there was pseudodominant inheritance, which had not been described in NPPK.'] Does highly prevalent SERPINB7 founder mutation cause pseudodominant inheritance pattern in Nagashima-type palmoplantar keratosis?