ClinVar

Description

The c.630G>A 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 also predicted to be deleterious by computational evidence, with a REVEL score of 0.9399, which is greater than the MDEP threshold of 0.70 (PP3). This variant is absent in gnomAD v2.1.1 (PM2_Supporting). This variant was identified in 4 unrelated individuals with hyperglycemia (PS4_Moderate, internal lab contributors). Two of these individuals had a clinical history highly specific for GCK-hyperglycemia (FBG 5.5-8 mmol/L and HbA1c 5.6 - 7.6% and negative antibodies and/or persistent fasting hyperglycemia) (PP4_Moderate; internal lab contributors). This variant segregated with hyperglycemia, with 3 informative meioses in 2 families (PP1_Moderate; internal lab contributors). 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). In summary, c.630G>A 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, PP1_Moderate, PP4_Moderate, PS4_Moderate, PP2, PP3, PM2_Supporting.