Knuckle Pads

A number sign (#) is used with this entry because knuckle pads are associated with certain genetic disorders such as epidermolytis palmoplantar keratoderma (144200) or Dupuytren contractures (126900), both of which are autosomal dominant.

Knuckle pads are sometimes associated with Dupuytren contractures and it is not completely certain that a different gene is involved. Camptodactyly (114200) also has an uncertain relationship. Skoog (1948) defined knuckle pads as 'subcutaneous nodules on the dorsal aspect of the proximal interphalangeal joints.'

Lu et al. (2003) reported association of knuckle pads with epidermolytic palmoplantar keratoderma in a Chinese family and identified a novel leu160-to-phe mutation in the keratin-9 gene (L160F; 607606.0012) as the presumed cause. They presented evidence that both the hyperkeratosis and the knuckle pads were friction-related.