T1D is often diagnosed by the detection of autoantibodies against insulin itself (specifically preproinsulin), the 65-kDa isoform of glutamic acid decarboxylase (GAD65), the phosphatase IA-2 and/or the zinc transporter ZnT8 (Mauvais et al., 2016). The gene discussed is GAD2; the disease is type 1 diabetes mellitus.