The c.1112G>A variant in the glucokinase gene, GCK, causes an amino acid change of cysteine to tyrosine at codon 371 (p.(Cys371Tyr)) of NM_000162.5. GCK is defined by the ClinGen MDEP VCEP as a gene that has a low rate of benign missense variation and where pathogenic missense variants are a common mechanism of disease (PP2). This variant is predicted to be deleterious by computational evidence, with a REVEL score of 0.956, which is greater than the MDEP VCEP threshold of 0.70 (PP3). This variant is absent from gnomAD v2.1.1 (PM2_Supporting). This variant segregated with diabetes with 5 informative meioses in a family with diabetes/hyperglycemia (PP1_Strong; internal lab contributors). This variant was identified in an individual with a phenotype suggestive of GCK-hyperglycemia; however, PP4 is unable to be evaluated due to insufficient clinical information (internal lab contributors). Another missense variant, c.1112G>T p.(Cys371Phe)​, has been classified as pathogenic by the ClinGen MDEP VCEP but has a greater Grantham distance than p.(Cys371Tyr)(PM5_Supporting). In summary, this variant meets the criteria to be classified as likely pathogenic for GENE-MODY. ACMG/AMP criteria applied, as specified by the ClinGen MDEP VCEP (specification version 1.2.0, approved 6/7/2023): PP2, PP3, PM2_Supporting, PP1_Strong, PM5_Supporting.