CTLA4 and cutaneous mastocytosis: CTLA-4 c.-1765C>T and c.-1478G>A were associated with a higher risk of developing red blood cell transfusion-associated adverse reactions due to the inhibition of regulatory mechanisms of lymphocyte activity, mainly from Treg cells [12], and the GG genotype of CTLA-4 c.-1661A>G and c.-1577G>A was associated with a better response to the blocker ipilimumab and long-term survival in metastatic CM patients [13], but, to our knowledge, the roles of CTLA-4 SNVs in CM are still unknown.