In combinations of four SNVs, individuals with JAK1 c.1648+1272GG plus JAK1 c.991-27CC plus JAK2 c.-1132GG plus STAT3 c.*1671TT, JAK1 c.1648+1272GG plus JAK1 c.991-27CC plus JAK2 c.-1132GG plus STAT3 c.-1937CC, JAK1 c.1648+1272GG plus JAK1 c.991-27CC plus STAT3 c.*1671TT plus STAT3 c.-1937CC >G, and JAK1 c.991-27CC plus JAK2 c.-1132GG plus STAT3 c.*1671TT plus STAT3 c.-1937CC genotypes had 3.56-, 3.21-, 3.95-, and 3.67-fold increased risks of CM incidence than those with the remaining genotypes, respectively. Here, STAT3 is linked to cutaneous mastocytosis.