DDX39B and myeloid sarcoma: For example, the RNA helicase DDX39B, a repressor of AS of IL7R exon 6, is downregulated in MS peripheral blood mononuclear cells, and consequently, the overexpression of the soluble form of the interleukin-7 receptor alpha chain gene (sIL7R) increases MS risk (Galarza-Munoz et al., 2017).