The frequencies of activated (CD38+) islet antigen-specific memory CD4+ T cells (reactive against GAD65, IGRP, ZnT8, ChgA, PPI78-90K88S or PPI35-47R46E) in the peripheral blood are elevated in people with T1D (ref. 92) (Table 1). This evidence concerns the gene CD4 and type 1 diabetes mellitus.