Novel R634W c-kit mutation identified in familial mastocytosis.

Familial mastocytosis is a well-documented but rare entity, with fewer than 100 cases reported in the literature. The etiology has most commonly been linked to activating c-kit mutations, with several mutations reported to date. We present a novel familial mastocytosis-associated c-kit mutation (R634W) in three siblings with urticaria pigmentosa. This mutation has been previously described in mucosal melanoma, chronic myelomonocytic leukemia, and acute myeloid leukemia. Because this is a rare mutation, it is unclear whether screening for other disease states associated with the mutation would be of benefit.