Urticaria Pigmentosa - Cause

Cause

The majority of urticaria pigmentosa cases are caused by a point mutation at amino acid 816 of the proto-oncogene c-kit. c-kit is a transmembrane protein which, when bound to Mast Cell Growth Factor (MCGF), signals the cell to divide. Mutations in position 816 of c-kit can result in a constant division signal being sent to the mast cells, resulting in abnormal proliferation. Different mutations have been linked to different onset times of the disease. For example, the Asp816Phe and Asp816Val mutations (the aspartate normally at position 816 in the c-kit protein has been replaced with phenylalanine or valine respectively) have been associated with early manifestation of the disease (mean age of onset: 1.3 and 5.9 months respectively).