ICA512, (also known as PTPRN, IA-2 or PTP35), and phogrin (also known as PTPRN2, IA-2 β or IAR), are homologous RPTP chiefly expressed in secretory granules (SG) of brain, pituitary, pancreatic islet, and adrenal endocrine cells and were originally identified as major autoantigens in type-1 diabetes mellitus [3], [4]. The gene discussed is PTPRN2; the disease is type 1 diabetes mellitus.