SETD2 and systemic mastocytosis: Given that SETD2 is the only methyltransferase able to trimethylate H3K36,7 and based on our previous findings in systemic mastocytosis (SM) where SETD2 loss of function leading to H3K36me3 impairment occurred much more frequently at the post‐translational rather than at the genetic/genomic or transcript level,25, 26 we opted for a WB‐based screening strategy to assess H3K36me3 as a surrogate marker of SETD2 loss of function, whichever the underlying cause.