Identification of causative gene variants for patients with known monogenic diabetes using a targeted next-generation sequencing panel in a single-center study

Aims We aimed to verify the usefulness of targeted next-generation sequencing (NGS) technology for diagnosing monogenic diabetes in a single center. Methods We designed an amplicon-based NGS panel targeting 34 genes associated with known monogenic diabetes and performed resequencing in 56 patients with autoantibody-negative diabetes mellitus diagnosed at < 50 years who had not been highly obese. By bioinformatic analysis, we filtered significant variants based on allele frequency (< 0.005 in East Asians) and functional prediction. We estimated the pathogenicity of each variant upon considering the family history. Results Overall, 16 candidate causative variants were identified in 16 patients. Among them, two previously known heterozygous nonsynonymous single-nucleotide variants associated with monogenic diabetes were confirmed as causative variants: one each in the GCK and WFS1 genes. The former was found in two independent diabetes-affected families. Two novel putatively deleterious heterozygous variants were also assumed to be causative from the family history: one frameshift and one nonsynonymous single-nucleotide variant in the HNF4A gene. Twelve variants remained as candidates associated with the development of diabetes. Conclusion Targeted NGS panel testing was useful to diagnose various forms of monogenic diabetes in combination with familial analysis, but additional ingenuity would be needed for practice.