Variants of Unknown Significance in Maturity-Onset Diabetes of the Young: High Rate of Conundrum Resolution via Variants of Unknown Significance Reanalysis.

Introduction: In the era of next-generation sequencing, clinicians frequently encounter variants of unknown significance (VUS) in genetic testing. VUS may be reclassified over time as genetic knowledge grows. We know little about how best to approach VUS in the maturity-onset diabetes of the young (MODY). Therefore, our study aimed to determine the utility of reanalysis of previous VUS results in genetic confirmation of MODY.

Methods: A single-center retrospective chart review identified 85 subjects with a MODY clinical diagnosis. We reanalyzed genetic testing in 10 subjects with 14 unique VUS on MODY genes that was performed >3 years before the study. Demographic, clinical, and biochemical data was collected for those individuals.

Results: After reanalysis, 43% (6/14) of the gene variants were reclassified to a different category: 7% (1/14) were "likely pathogenic" and 36% (5/14) were "benign" or "likely benign." The reclassified pathogenic variant was in HNF1A and all reclassified benign variants were in HNF1A, HNF1B and PDX1. The median time between MODY testing and reclassification was 8 years (range: 4-10 years).

Conclusion: In sum, iterative reanalyzing the genetic data from VUS found during MODY testing may provide high-yield diagnostic information. Further studies are warranted to identify the optimal time and frequency for such analyses.