By enumerating and phenotypically characterizing DC-10 in the peripheral blood of subjects at different stages of T1D development—first-degree relatives (FDRs) of T1D patients, without (Abneg) or with (Abpos) autoantibodies, T1D patients at onset, and age-matched healthy controls (HCs)—we showed that DC-10 contain a high proportion of HLA-G-expressing cells as compared with monocytes. The gene discussed is HLA-G; the disease is type 1 diabetes mellitus.