7-44145637-G-T

Position:

• chr7-44145637-G-T

Variant summary

Our verdict is Pathogenic. Variant got 11 ACMG points: 11P and 0B. PP4_Moderate PVS1 PM2_Supporting

This summary comes from the ClinGen Evidence Repository: The c.1113C>A variant in the glucokinase gene, GCK, results in a premature termination at codon 371 (p.(Cys371Ter)) of NM_000162.5. This variant, located in biologically-relevant exon 9/10, is predicted to lead to nonsense-mediated decay in a gene in which loss-of-function is an established disease mechanism (PVS1). This variant is absent from gnomAD v2.1.1 (PM2_Supporting). This variant was identified in an individual with 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; internal lab contributors). In summary, this variant meets the criteria to be classified as pathogenic for monogenic diabetes. ACMG/AMP criteria applied, as specified by the ClinGen MDEP VCEP (specification version 1.2.0, approved 6/7/2023): PVS1, PM2_Supporting, PP4_Moderate. LINK:https://erepo.genome.network/evrepo/ui/classification/CA367398930/MONDO:0015967/086

• Frequency: Genomes: not found (cov: 33)
• Consequence: GCK ENST00000403799.8 stop_gained
• Clinical Significance: Pathogenic reviewed by expert panel P:4
• Conservation: PhyloP100: 0.0240

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 Pathogenic. Variant got 11 ACMG points.

• PVS1: For more information check the summary or visit ClinGen Evidence Repository.
• PM2: For more information check the summary or visit ClinGen Evidence Repository.
• PP4: For more information check the summary or visit ClinGen Evidence Repository.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
GCK	NM_000162.5	c.1113C>A	p.Cys371Ter	stop_gained	9/10	ENST00000403799.8	NP_000153.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
GCK	ENST00000403799.8	c.1113C>A	p.Cys371Ter	stop_gained	9/10	1	NM_000162.5	ENSP00000384247	P1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 33

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:4

Revision: reviewed by expert panel

Submissions by phenotype

not provided Pathogenic:2

Pathogenic, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Oct 24, 2023	This sequence change creates a premature translational stop signal (p.Cys371*) in the GCK gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in GCK are known to be pathogenic (PMID: 7553875, 9867845, 14578306, 24323243, 25015100). This variant is not present in population databases (gnomAD no frequency). This premature translational stop signal has been observed in individual(s) with maturity onset diabetes of the young (PMID: 25555642, 31063852). ClinVar contains an entry for this variant (Variation ID: 617645). For these reasons, this variant has been classified as Pathogenic. -
Pathogenic, criteria provided, single submitter	clinical testing	Athena Diagnostics	Dec 11, 2020	This variant is expected to result in the loss of a functional protein. This variant has not been reported in large, multi-ethnic general populations (http://gnomad.broadinstitute.org). This variant has been identified in at least one individual with clinical features associated with this gene. -

Maturity-onset diabetes of the young type 2 Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Translational Genomics Laboratory, University of Maryland School of Medicine

Apr 25, 2017

The c.1113C>A variant in codon 371 (exon 9) of the glucokinase gene, GCK, results in the generation of a stop codon. The c.1113C>A variant was not observed in the NHLBI Exome Sequencing Project, 1000 Genomes Project, or Exome Aggregation Consortium databases; however, loss of function nonsense mutations in the GCK gene, including ones in exon 9, have been reported previously in patients with Maturity-Onset Diabetes of the Young, Type 2 (MODY2) (19790256). Additionally, multiple lines of computational evidence (MutationTaster, LRT, CADD) predict this variant is probably damaging to the protein structure, function, or protein-protein interaction. ACMG criteria = PVS1, PM2, PP3 -

Monogenic diabetes Pathogenic:1

Pathogenic, reviewed by expert panel

curation

ClinGen Monogenic Diabetes Variant Curation Expert Panel

Aug 09, 2023

The c.1113C>A variant in the glucokinase gene, GCK, results in a premature termination at codon 371 (p.(Cys371Ter)) of NM_000162.5. This variant, located in biologically-relevant exon 9/10, is predicted to lead to nonsense-mediated decay in a gene in which loss-of-function is an established disease mechanism (PVS1). This variant is absent from gnomAD v2.1.1 (PM2_Supporting). This variant was identified in an individual with 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; internal lab contributors). In summary, this variant meets the criteria to be classified as pathogenic for monogenic diabetes. ACMG/AMP criteria applied, as specified by the ClinGen MDEP VCEP (specification version 1.2.0, approved 6/7/2023): PVS1, PM2_Supporting, PP4_Moderate. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Pathogenic	0.46
CADD	Pathogenic	36
DANN	Uncertain	0.98
Eigen	Benign	0.12
Eigen_PC	Benign	-0.077
FATHMM_MKL	Uncertain	0.87	D
MutationTaster	Benign	1.0	A;A;A;A
Vest4		0.94
GERP RS		0.73

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: rs556581174; hg19: chr7-44185236;