May serve an important special function either in the mature palmar and plantar skin tissue or in the morphogenetic program of the formation of these tissues. Plays a role in keratin filament assembly.
Expressed in the terminally differentiated epidermis of palms and soles.
Involvement in disease
Defects in KRT9 are a cause of palmoplantar keratoderma epidermolytic (EPPK) [MIM:144200]; also abbreviated as EHPPK. EPPK is a dermatological disorder characterized by diffuse thickening of the epidermis on the entire surface of palms and soles sharply bordered with erythematous margins. Some patients may present with knuckle pads, thick pads of skin appearing over the proximal phalangeal joints.