7-44145173-G-T

Position:

• chr7-44145173-G-T

Variant summary

Our verdict is Likely pathogenic. Variant got 7 ACMG points: 7P and 0B. PP2 PP3 PM2_Supporting PS3_Moderate PS4_Moderate

This summary comes from the ClinGen Evidence Repository: The c.1361C>A variant in the glucokinase gene, GCK, causes an amino acid change of alanine to glutamic acid at codon 454 (p.(Ala454Glu)) 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 0.965, which is greater than the MDEP VCEP threshold of 0.70 (PP3). MDEP wild type quality control measures were met, and the relative activity Index (RAI) of this variant was found to be 0.04, which is below the MDEP cutoff (<0.5) (PMID:28842611). This variant is absent from gnomAD v2.1.1 (PM2_Supporting). This variant was identified in 6 unrelated individuals with hyperglycemia (PS4_Moderate; ClinVar: 393447, PMIDs: 36257325, 20337973, 16602010, 17204055, internal lab contributors). In summary, c.1361C>A meets the criteria to be classified as likely pathogenic for monogenic diabetes. ACMG/AMP criteria applied, as specified by the ClinGen MDEP (specification version 1.3.0, approved 8/11/2023): PS3_Moderate, PS4_Moderate, PP2, PP3, PM2_Supporting. LINK:https://erepo.genome.network/evrepo/ui/classification/CA16609264/MONDO:0015967/086

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0 (0 hom.)
  • Failed GnomAD Quality Control
• Consequence: GCK NM_000162.5 missense
• Clinical Significance: Likely pathogenic reviewed by expert panel P:5
• Conservation: PhyloP100: 9.43

Genes affected

GCK (HGNC:4195): (glucokinase) This gene encodes a member of the hexokinase family of proteins. Hexokinases phosphorylate glucose to produce glucose-6-phosphate, the first step in most glucose metabolism pathways. In contrast to other forms of hexokinase, this enzyme is not inhibited by its product glucose-6-phosphate but remains active while glucose is abundant. The use of multiple promoters and alternative splicing of this gene result in distinct protein isoforms that exhibit tissue-specific expression in the pancreas and liver. In the pancreas, this enzyme plays a role in glucose-stimulated insulin secretion, while in the liver, this enzyme is important in glucose uptake and conversion to glycogen. Mutations in this gene that alter enzyme activity have been associated with multiple types of diabetes and hyperinsulinemic hypoglycemia. [provided by RefSeq, Aug 2017]

ACMG classification

Verdict is Likely_pathogenic. Variant got 7 ACMG points.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
GCK	NM_000162.5	c.1361C>A	p.Ala454Glu	missense_variant	10/10	ENST00000403799.8

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
GCK	ENST00000403799.8	c.1361C>A	p.Ala454Glu	missense_variant	10/10	1	NM_000162.5	P1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Data not reliable, filtered out with message: AC0 AF: 0.00 AC: 0 AN: 1457766 Hom.: 0 Cov.: 31 AF XY: 0.00 AC XY: 0 AN XY: 725134

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:5

Revision: reviewed by expert panel

Submissions by phenotype

Monogenic diabetes Pathogenic:3

Likely pathogenic, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	Mar 27, 2024	Variant summary: GCK c.1361C>A (p.Ala454Glu) results in a non-conservative amino acid change located in the Hexokinase, C-terminal domain (IPR022673) of the encoded protein sequence. Five of five in-silico tools predict a damaging effect of the variant on protein function. The variant was absent in 239696 control chromosomes (gnomAD). c.1361C>A has been reported in the literature in individuals affected with MODY (Feigerlov_2006, Pinterova_2007, Pruhova_2010, Flannick_2013, Mirshahi_2022). These data indicate that the variant is likely to be associated with disease. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. The following publications have been ascertained in the context of this evaluation (PMID: 16602010, 24097065, 36257325, 19790256, 17204055, 20337973). ClinVar contains an entry for this variant (Variation ID: 393447). Based on the evidence outlined above, the variant was classified as likely pathogenic. -
Likely pathogenic, criteria provided, single submitter	clinical testing	Translational Genomics Laboratory, University of Maryland School of Medicine	Jun 17, 2016	The c.1361C>A variant in codon 454 (exon 10) of the glucokinase gene, GCK, results in the substitution of Alanine to Glutamic acid. The c.1361C>A variant was not observed in the NHLBI Exome Sequencing Project, 1000 Genomes Project, or Exome Aggregation Consortium databases; however, this variant has been reported in the literature in patients with a clinical picture consistent with Maturity-Onset Diabetes of the Young, Type 2 (MODY2, also called GCK-MODY) ( 16602010; 17204055; 20337973). Different amino acid substitutions at this residue, Ala454Val (14517956) and Ala454Thr (22035297), have also been reported in patients with MODY2. Additionally, multiple lines of computational evidence (SIFT, Polyphen, MutationTaster, MutationAssessor, LRT, FATHMM, SVM, LR, CADD, GERP) predict this variant is probably damaging to the protein structure, function, or protein-protein interaction; ACMG Criteria = PS4, PM2, PP3 -
Likely pathogenic, reviewed by expert panel	curation	ClinGen Monogenic Diabetes Variant Curation Expert Panel	Mar 31, 2024	The c.1361C>A variant in the glucokinase gene, GCK, causes an amino acid change of alanine to glutamic acid at codon 454 (p.(Ala454Glu)) 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 0.965, which is greater than the MDEP VCEP threshold of 0.70 (PP3). MDEP wild type quality control measures were met, and the relative activity Index (RAI) of this variant was found to be 0.04, which is below the MDEP cutoff (<0.5) (PMID: 28842611). This variant is absent from gnomAD v2.1.1 (PM2_Supporting). This variant was identified in 6 unrelated individuals with hyperglycemia (PS4_Moderate; ClinVar: 393447, PMIDs: 36257325, 20337973, 16602010, 17204055, internal lab contributors). In summary, c.1361C>A meets the criteria to be classified as likely pathogenic for monogenic diabetes. ACMG/AMP criteria applied, as specified by the ClinGen MDEP (specification version 1.3.0, approved 8/11/2023): PS3_Moderate, PS4_Moderate, PP2, PP3, PM2_Supporting. -

Microcephaly, normal intelligence and immunodeficiency Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Mar 27, 2024

Variant summary: NBN c.1361C>A (p.Ser454Tyr) results in a non-conservative amino acid change in the encoded protein sequence. Four of five in-silico tools predict a damaging effect of the variant on protein function. The variant allele was found at a frequency of 4e-06 in 251230 control chromosomes. The available data on variant occurrences in the general population are insufficient to allow any conclusion about variant significance. To our knowledge, no occurrence of c.1361C>A in individuals affected with Nijmegen Breakage Syndrome and no experimental evidence demonstrating its impact on protein function have been reported. Six submitters have cited clinical-significance assessments for this variant to ClinVar after 2014. All submitters classified the variant as uncertain significance. Based on the evidence outlined above, the variant was classified as uncertain significance. -

not provided Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

GeneDx

Nov 19, 2021

Published functional studies demonstrate p.(A454E) has a damaging effect on protein function (imkov et al., 2017); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; Missense variants in this gene are often considered pathogenic (Stenson et al., 2014); This variant is associated with the following publications: (PMID: 17204055, 16602010, 20337973, 28842611) -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.99
BayesDel_addAF	Pathogenic	0.58	D
BayesDel_noAF	Pathogenic	0.59
CADD	Pathogenic	29
DANN	Uncertain	1.0
Eigen	Pathogenic	0.98
Eigen_PC	Pathogenic	0.86
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Pathogenic	0.99	D;D;D;.;D;D
M_CAP	Pathogenic	0.88	D
MetaRNN	Pathogenic	0.99	D;D;D;D;D;D
MetaSVM	Pathogenic	1.1	D
MutationTaster	Benign	1.0	D;D;D;D
PrimateAI	Uncertain	0.78	T
Sift4G	Pathogenic	0.0	D;D;D;D;D;D
Polyphen		1.0	D;.;D;D;D;D
Vest4		0.95
MutPred		0.96		.;.;Gain of disorder (P = 0.0359);.;.;.;
MVP		0.98
MPC		2.3
ClinPred		1.0	D
GERP RS		5.8
Varity_R		0.98
gMVP		1.0

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.0		Details are displayed if max score is > 0.2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

LitVar

Other links and lift over

dbSNP: rs1057524900; hg19: chr7-44184772;