[citation needed] The majority of urticaria pigmentosa cases are caused by a point mutation at amino acid 816 of the proto-oncogene c-kit.

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).

[5] Several factors can worsen the symptoms of urticaria pigmentosa: [citation needed] The classification of NSAIDs can be disputed.

[7] At least one clinical study suggested that nifedipine, a calcium channel blocker used to treat high blood pressure, may reduce mast cell degranulation in patients with urticaria pigmentosa.

A 1984 study by Fairly et al. included a patient with symptomatic urticaria pigmentosa who responded to nifedipine taken three times daily.

[citation needed] Urticaria pigmentosa is a rare disease, affecting fewer than 200,000 people in the United States.