Heterogeneous nature of diabetes in a family with a gain-of-function mutation in the ATP-binding cassette subfamily C member 8 (ABCC8) gene

Abstract

Gain-of-function ATP-binding cassette subfamily C member 8 (ABCC8) mutations are known to cause neonatal diabetes mellitus and maturity-onset diabetes in the young. However, the intrafamilial heterogeneous nature of diabetes caused by the ABCC8 mutation is not fully understood to date. To clarify the intrafamilial heterogeneous nature of monogenetic diabetes, we conducted a case study on a family with ABCC8 mutations. We investigated eight family members, including a neonatal diabetes patient, based on metabolic features and genetic analysis. All coding exons and exon–intron boundaries of the KCNJ11, ABCC8, GCK, HNF1A, and HNF4A genes were amplified from genomic DNA and directly sequenced. Five gene mutation carriers with ABCC8 (c.1819G>A/p.V607M) were identified in this family, and the onset and severity of diabetes progressively worsened across the three generations. Each of the ABCC8 gene mutation carrier family members were diagnosed with diabetes as follows: the grandfather with type 2 diabetes at 35 years of age, the aunt with slowly-progressive insulin-dependent diabetes at 18 years of age, the mother with ketosis-onset insulin-dependent diabetes at 14 years of age, the sister with impaired glucose tolerance at 9 years of age, and the proband with transient neonatal diabetes at birth. The present study shows the heterogeneous nature of diabetes in a family with a gain-of-function mutation in the ABCC8 gene.