GAD2 and type 1 diabetes mellitus: It has been shown that serum samples from first degree relative of T1D patients that tested positive for autoantibodies reactive to full length IA-2 (IA-FL) and GAD65 but negative for the IA-2 intracellular protein constructs (ICA512bdc) harbored 100% cumulative risk of developing the disease within 11 years of follow up.