Ring sideroblasts are characterised by an excess accumulation of iron in the mitochondria of erythroblasts,10 and SF3B1 mutant RARS cases show altered iron distribution characterised by coarse iron deposits compared with wild-type RARS cases.11SF3B1 mutations are generally more prevalent in low-risk MDS and have been shown to be independent predictors of favorable clinical outcome in MDS in most studies.8, 11 The clinical consequences of SF3B1 mutation in MDS are clear, but the functional consequences of these mutations in human cells remain poorly understood. The gene discussed is RARS1; the disease is myelodysplastic syndrome.