A novel BLK heterozygous mutation (p.Met121lle) in maturity‐onset diabetes mellitus: A case report and literature review

Maturity onset diabetes of the young (MODY) is a highly heterogeneous monogenic disease that occurs due to β-cell dysfunction. It is divided into different types depending on the gene mutated, and a total of 16 genes have been found to be associated with MODY. However, due to the current lack of understanding of monogenic diabetes, 90% of MODY is currently misdiagnosed and ignored in clinical practice. In this paper, we report the clinical data of a patient diagnosed with diabetes. Genetic testing revealed a novel BLK heterozygous mutation (c.363G>A) in the patient and in his father and son. He had no islet-specific autoantibodies and showed a reduced meal-induced response of insulin. Precise diagnosis of MODY individuals is important to the treatment.