R162W Mutation of Keratin 9 in a Family with Autosomal Dominant Palmoplantar Keratoderma with Unique Histologic Features

Recurrent R162W mutation of keratin 9 has been reported in multiple families with epidermolytic hyperkeratosis (EHK)-type hereditary palmoplantar keratoderma (PPK). Recently, we have observed a family whose members showed autosomal-dominant PPK with unique histologic features such as rounded, dissociated, and slightly eosinophilic keratinocytes at the middle spinous and granular layers of epidermis, but without the distinct EHK pheno-type. To investigate the genotype-phenotype correlation in this family, we searched for a mutation of keratin 9 and found R162W substitution in the coiled 1A region. This mutation was not detected in 50 control individuals. These results may further our understanding of the pathogenesis of EHK