ICOS and type 1 diabetes mellitus: To further refine this population, which was also moderately increased in T1D (Fig. 3g; T-statistic = 2.95, P = 2.2e-2, BH-corrected t test; Supplementary Datasets 3, 4), we subset and re-performed feature selection and clustering, successfully identifying 3 discrete populations (Supplementary Fig. 9a, b; Supplementary Datasets 7), with the largest CD4+ effector cluster existing along a cell-identify marked by a STAT4/RUNX2-to-TSHZ2/ICOS expression continuum (Supplementary Fig. 9c)44,45.