A recent proteomic discovery study using monozygotic twins discordant for T1D identified 5 other exocrine proteins as promising biomarkers for T1D: chymotrypsinogen B, chymotrypsinogen B2, trypsinogen 1, trypsinogen 2, and carboxypeptidase B1 (25). The gene discussed is CTRB2; the disease is type 1 diabetes mellitus.