ClinVar Miner

Submissions for variant NM_000162.5(GCK):c.449T>A (p.Phe150Tyr)

dbSNP: rs193922297
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Total submissions: 4
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Submitter RCV SCV Clinical significance Condition Last evaluated Review status Method Comment
ClinGen Monogenic Diabetes Variant Curation Expert Panel RCV003226201 SCV004242363 pathogenic Monogenic diabetes 2024-01-06 reviewed by expert panel curation The c.449T>A variant in the glucokinase gene, GCK, causes an amino acid change of phenylalanine to tyrosine at codon 150 (p.(Phe150Tyr)) 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 0.962, 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 was identified in 10 unrelated individuals with hyperglycemia (PS4; PMIDs: 25306193, 19564454, 32086287, 30663027, 28726111, 22761713, internal lab contributors). One 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) (PP4_Moderate; PMID: 28726111). This variant segregated with hyperglycemia, with 3 informative meioses in 2 families (PP1_Moderate; internal lab contributors). MDEP wild type quality control measures were met, and the relative activity Index (RAI) of this variant was found to be 0.014, which is below the MDEP cutoff (<0.5) (PS3_Moderate, PMID: 22761713). In summary, c.449T>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): PS4, PP1_Moderate, PP4_Moderate, PS3_Moderate, PP2, PP3, PM2_Supporting.
Genetic Services Laboratory, University of Chicago RCV000117129 SCV000151290 uncertain significance not provided 2013-02-21 criteria provided, single submitter clinical testing
Women's Health and Genetics/Laboratory Corporation of America, LabCorp RCV003226201 SCV003922548 pathogenic Monogenic diabetes 2023-03-23 criteria provided, single submitter clinical testing Variant summary: GCK c.449T>A (p.Phe150Tyr) results in a conservative amino acid change located in the Hexokinase, N-terminal domain (IPR022672) of the encoded protein sequence. Four of five in-silico tools predict a damaging effect of the variant on protein function. The variant was absent in 251462 control chromosomes. c.449T>A has been reported in the literature in settings of individuals affected with incidental hyperglycemia, MODY, gestational/monogenic diabetes and laboratory testing cohorts (example, Lorini_2009, Capuano_2012, Alkorta-Aranburu_2014, Aloi_2017, Zubkova_2019, Stankute_2020, Ivanoshchuk_2021). Of these, only the subset of individuals/cohorts reporting diagnostic findings supportive of MODY/monogenic diabetes were captured in this ascertainment (example, Aloi_2017, Stankute_2020, Ivanoshchuk_2021). These data indicate that the variant is likely to be associated with disease. At least one publication reports experimental evidence evaluating an impact on protein function (example, Capuano_2012). The most pronounced variant effect results in <10% of normal GCK activity in-vitro. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014. Based on the evidence outlined above, the variant was classified as pathogenic.
Invitae RCV000117129 SCV004295180 uncertain significance not provided 2023-02-24 criteria provided, single submitter clinical testing This sequence change replaces phenylalanine, which is neutral and non-polar, with tyrosine, which is neutral and polar, at codon 150 of the GCK protein (p.Phe150Tyr). This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individual(s) with autosomal dominant GCK-related conditions (PMID: 19564454). ClinVar contains an entry for this variant (Variation ID: 129142). Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) has been performed at Invitae for this missense variant, however the output from this modeling did not meet the statistical confidence thresholds required to predict the impact of this variant on GCK protein function. Experimental studies have shown that this missense change affects GCK function (PMID: 22761713). This variant disrupts the p.Phe150 amino acid residue in GCK. Other variant(s) that disrupt this residue have been observed in individuals with GCK-related conditions (PMID: 12627330), which suggests that this may be a clinically significant amino acid residue. In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance.

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