Genetic testing for monogenic diabetes with next generation sequencing: The first 6 months

Abstract

Introduction: The incidence of monogenic diabetes is estimated to be 2-5% of the diabetic population. To date over 30 genes have been reported to cause monogenic diabetes. In the past, diagnostic strategies have relied on the clinical and biochemical phenotype to determine the target gene(s) and testing sequence. This approach is expensive, time consuming, and often unsuccessful. Next Generation Sequencing (NGS) offers a fast and cost effective alternative for screening for monogenic diabetes. NGS enables the simultaneous analysis of multiple genes in a single test at a fraction of the cost of traditional Sanger sequencing methods. Objective: We describe our experience after 6 months of testing for monogenic diabetes by NGS. Methods: Genetic testing was performed using a custom NGS panel that contained probes for 15 of the most common genes associated with monogenic diabetes Maturity Onset Diabetes of the Young or Permanent Neonatal Diabetes. Previously, the laboratory had employed Sanger sequencing to test for a limited number of genes. Target enrichment was carried out using the custom Illumina Nextera rapid capture probe set, followed by sequencing on an Illumina MiSeq. Data analysis was carried out by CLC Genomics Workbench and genetic variants were annotated using Cartagenia software. Results: We tested 59 patients referred to the laboratory for monogenic diabetes. We detected mutations in 24 patients in 9 different genes (ABCC8, GCK, HNF1A, HNF1B, HNF4A, INS, INSR, KCNJ11 and PAX4). Approximately 46% of these cases would not have been detected with our previous Sanger sequencing approach. In these cases there was either a mutation in a gene that had not been requested for sequencing, or a mutation in a gene that had not been previously tested by Sanger sequencing in our laboratory. Conclusions: NGS has significantly increased the number of patients given a molecular diagnosis in a cost effective and clinically relevant timeframe.L720733912015-11-20 <br />