Palmoplantar keratosis type nagashima

The "Nagashima type" of palmoplantar keratoses is an autosomal recessive non-syndromal, transgenic diffuse palmoplantar keratosis (PKK).

Detection of a loss-of-function mutation in the SERPINB7 gene. The gene product belongs to the family of serine protease inhibitors.

Clinically, the genodermatosis (so far only described in Asians) is characterized by a sharply limited, progressive and transgressive diffuse palmoplantar keratosis with marginal redness, which spreads over the foot and hand edges to the dorsal areas. Keratotic involvement of the Achilles tendon region has been described. The diffuse keratoses are usually mild and not progressive (distinguishing feature from Mal de Meleda). Clinically characteristic is the observation that after contact with water, the keratoses swell very briefly to a spongy whitish appearance (washerwoman's hands), due to the lack of intergrity of the stratum corneum.

S.u. Keratosis palmoplantaris (overview)

SERPINB7 is especially detected in the cytoplasm of the stratum granulosum and stratum corneum of the epidermis.

1. Kubo A et al(2013) Mutations in SERPINB7, encoding a member of the serine protease inhibitor superfamily, cause Nagashima-type palmoplantar keratosis. At J Hum Genet 93:945-956