The IL2RA gene has been associated with differences in immune cell populations in subjects with MS, and Hartmann et al. found that individuals carrying the IL2RA risk alleles present a significantly increased propensity of TH (T helper) cells to develop into GM-CSF- (granulocyte-macrophage colony-stimulating factor-) producing memory TH-cells and linked this genetic risk factor with a functional feature of TH-cells in MS [30]. The gene discussed is CSF2; the disease is myeloid sarcoma.