The c.630G>T variant in the glucokinase gene, GCK, causes an amino acid change of methionine to isoleucine at codon 210 (p.(Met210Ile)) of NM_000162.5. GCK is defined by the ClinGen MDEP as a gene that has a low rate of benign missense variation and has pathogenic missense variants as a common mechanism of disease (PP2). This variant is predicted to be deleterious by computational evidence, with a REVEL score of 0.9399, which is greater than the MDEP VCEP threshold of 0.70 (PP3). This variant is absent in gnomAD v2.1.1 (PM2_Supporting), and was identified in an individual with diabetes; however, PP4 is unable to be evaluated due to lack of clinical information (ClinVar ID 36236). Two other missense variants, c.629T>A (p.Met210Lys) and c.629T>C (p.Met210Thr), have been classified as pathogenic by the ClinGen MDEP (PM5_Strong). The nucleotide change c.630G>A, which causes the same amino acid change, has been classified as pathogenic for monogenic diabetes by the ClinGen MDEP (PS1). Taken together, the c.630G>T meets the criteria to be classified as pathogenic for monogenic diabetes. ACMG/AMP criteria applied, as specified by the ClinGen MDEP (specification version 1.3.0, approved 8/11/2023): PM5_Strong, PS1, PP2, PP3, PM2_Supporting.