Likewise, U2AF1 mutations are also relatively rare in SM, with a higher incidence in AdvSM [10,29,50] vs. Non-AdvSM cases (6% vs. 1%, respectively) (Table S2); these mutations are mostly located at codons S34 [29,157,158] and Q157 [29] of the U2AF1 gene (Table S1). Here, U2AF1 is linked to systemic mastocytosis.