For example, mutations in SF3B1 are highly enriched in MDS patients with ringed sideroblasts (Papaemmanuil et al. 2011; Yoshida et al. 2011), which represents an indolent form of MDS marked by hyperplasia of erythroid precursor cells with aberrant accumulation of mitochondrial ferritin around the nucleus. The gene discussed is SF3B1; the disease is myelodysplastic syndrome.