Schematic representation of our current understanding of the relationship between the occurrence of a somatic SF3B1 mutation and the formation of ring sideroblasts in patients with RARS. Previous studies found reduced expression of ABCB7 in CD34-positive cells and cultured erythroblasts from RARS patients,^23,24  whereas a recent study has shown altered ABCB7 exon usage in primary RARS cells.³⁶  The interconnection between DNA transcription and RNA splicing, illustrated in Figure 2, is consistent with the conclusion that a somatic SF3B1 mutation may result in reduced transcription and abnormal splicing of ABCB7.