7-44145266-A-T

Variant names:

• chr7-44145266-A-T
• rs193922273
• NM_000162.5:c.1268T>A

Variant summary

Our verdict is Pathogenic. Variant got 11 ACMG points: 11P and 0B. PP4_Moderate PM2_Supporting PP2 PP3 PS4 PP1_Moderate

This summary comes from the ClinGen Evidence Repository: The c.1268T>A variant in the glucokinase gene, GCK, causes an amino acid change of phenylalanine to tyrosine at codon 423 (p.(Phe423Tyr)) 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 0.801, 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 eight unrelated individuals with hyperglycemia (PS4; PMIDs: 23843579, 31968686, internal lab contributors). This variant segregated with hyperglycemia, with three informative meioses in two families (PP1_Moderate; PMIDs: 28012402, 23843579). 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 OGTT with minimal increment <3 mmol/l) (PP4_Moderate; PMID:23843579). In summary, c.1268T>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, PP4_Moderate, PP1_Moderate, PM2_supporting, PP2, PP3. LINK:https://erepo.genome.network/evrepo/ui/classification/CA213740/MONDO:0015967/086

• Frequency: Genomes: not found (cov: 33)
• Consequence: GCK NM_000162.5 missense
• Clinical Significance: Pathogenic reviewed by expert panel P:3
• Conservation: PhyloP100: 5.65

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.

• PS4: For more information check the summary or visit ClinGen Evidence Repository.
• PM2: For more information check the summary or visit ClinGen Evidence Repository.
• PP1: For more information check the summary or visit ClinGen Evidence Repository.
• PP2: For more information check the summary or visit ClinGen Evidence Repository.
• PP3: 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 rank	MANE	Protein	UniProt
GCK	NM_000162.5	c.1268T>A	p.Phe423Tyr	missense_variant	Exon 10 of 10	ENST00000403799.8	NP_000153.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
GCK	ENST00000403799.8	c.1268T>A	p.Phe423Tyr	missense_variant	Exon 10 of 10	1	NM_000162.5	ENSP00000384247.3

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 33

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:3

Revision: reviewed by expert panel

Submissions by phenotype

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

Aug 18, 2011

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

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing;curation

- -

Monogenic diabetes Pathogenic:1

Apr 27, 2024

ClinGen Monogenic Diabetes Variant Curation Expert Panel

Significance: Pathogenic

Review Status: reviewed by expert panel

Collection Method: curation

The c.1268T>A variant in the glucokinase gene, GCK, causes an amino acid change of phenylalanine to tyrosine at codon 423 (p.(Phe423Tyr)) 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 0.801, 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 eight unrelated individuals with hyperglycemia (PS4; PMIDs: 23843579, 31968686, internal lab contributors). This variant segregated with hyperglycemia, with three informative meioses in two families (PP1_Moderate; PMIDs: 28012402, 23843579). 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 OGTT with minimal increment <3 mmol/l) (PP4_Moderate; PMID: 23843579). In summary, c.1268T>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, PP4_Moderate, PP1_Moderate, PM2_supporting, PP2, PP3. -

not provided Pathogenic:1

Nov 09, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces phenylalanine, which is neutral and non-polar, with tyrosine, which is neutral and polar, at codon 423 of the GCK protein (p.Phe423Tyr). This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individual(s) with autosomal dominant maturity-onset diabetes of the young (MODY) (PMID: 23843579, 28170077, 36208343). It has also been observed to segregate with disease in related individuals. ClinVar contains an entry for this variant (Variation ID: 36189). Invitae Evidence Modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) indicates that this missense variant is not expected to disrupt GCK protein function with a negative predictive value of 80%. For these reasons, this variant has been classified as Pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.57
BayesDel_addAF	Pathogenic	0.46	D
BayesDel_noAF	Pathogenic	0.42
CADD	Pathogenic	28
DANN	Uncertain	1.0
DEOGEN2	Benign	0.22	.;T;D;.;.;.
Eigen	Uncertain	0.44
Eigen_PC	Uncertain	0.52
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Benign	0.76	T;T;T;.;T;T
M_CAP	Pathogenic	0.70	D
MetaRNN	Pathogenic	0.97	D;D;D;D;D;D
MetaSVM	Pathogenic	1.0	D
MutationAssessor	Benign	1.8	.;.;L;.;.;.
PrimateAI	Uncertain	0.77	T
PROVEAN	Benign	-1.2	.;N;N;N;N;N
REVEL	Pathogenic	0.80
Sift	Uncertain	0.0010	.;D;D;D;D;D
Sift4G	Uncertain	0.0020	D;D;D;D;D;D
Polyphen		1.0	D;.;D;D;B;B
Vest4		0.80
MutPred		0.89		.;.;Loss of stability (P = 0.0961);.;.;.;
MVP		0.96
MPC		2.3
ClinPred		0.94	D
GERP RS		5.8
Varity_R		0.88
gMVP		0.98

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.040		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: rs193922273; hg19: chr7-44184865;