KIT and mastocytosis: The frequency of the KIT D816 V mutation, a hallmark of SM, was found to be similar between HαT-negative and HαT-positive mastocytosis in the German (18) and the French (19) studies, although the D816 V mutation was less frequent in HαT-positive mastocytosis compared to HαT-negative mastocytosis in the Italian cohort (23).