pachyonychia congenita

pachyonychia congenita An inherited condition that is characterized by abnormally thick, curved nails; thickening of the skin of the palms, soles, knees, and elbows; and white plaques in the mouth. Abbreviated PC. There are two distinct syndromes of PC. The basic abnormality in both is a mutation in one of the genes for keratin, which is a primary constituent of nails, hair, and skin.