A recent study used a robust statistical test for disease associations with single cell data, called as MASC (mixed-effects modeling of associations of single cells), to show that the frequency of two Treg subsets expressing high levels of CD25 and Foxp3 was significantly reduced among resting CD4+ memory T cells in the peripheral blood of RA patients [60]. The gene discussed is IL2RA; the disease is rheumatoid arthritis.