Description
The c.835G>C variant in the glucokinase gene, GCK, causes an amino acid change of glutamic acid to glutamine at codon 279 (p.(Glu279Gln)) 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 has a Popmax Filtering allele frequency in gnomAD 2.1.1 of 0.000112, which is greater than the MDEP threshold for BA1 (>=0.0001) (BA1). This variant was identified in at least 4 unrelated individuals with non-autoimmune and non-absolute/near-absolute insulin-deficient diabetes; however, PS4 cannot be applied because the variant MAF in gnomAD is above the ClinGen MDEP PM2_Supporting cutoff (PMID 8446612, PMID 24097065, PMID 30245511, internal lab contributor). This variant has a REVEL score of 0.698, which is between the ClinGen MDEP thresholds predicting neither a damaging nor benign impact on GCK function. While functional studies exploring the effect of this mutation on the gene have been assessed, these studies do not meet the criteria set forth by the MDEP for application of PS3 or BS3 (PMID: 8446612). In summary, c.835G>C meets the criteria to be classified as benign for monogenic diabetes. ACMG/AMP criteria applied, as specified by the ClinGen MDEP (specification version 1.2.0, approved 6/7/2023): BA1, PP2.
| # | Sample | Method | Observation |
|---|
| Origin | Affected | Number tested | Tissue | Purpose | Method | Individuals | Allele frequency | Families | Co-occurrences |
|---|
| 1 | germline | unknown | not provided | not provided | not provided | | not provided | not provided | not provided | not provided |
