A study by Ansó et al. demonstrated that loss of the mitochondrial complex III subunit Rieske iron–sulfur protein (RISP) in fetal mouse HSCs allows them to proliferate but impairs their differentiation, resulting in anemia and prenatal death, while RISP inactivation in adult HSCs also impaired respiration, resulting in loss of quiescence concomitant with severe pancytopenia and lethality. This evidence concerns the gene UQCRFS1 and Pancytopenia.