7-44145266-A-T

Position:

• chr7-44145266-A-T

Variant summary

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

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 ENST00000403799.8 missense
• Clinical Significance: Pathogenic reviewed by expert panel P:2
• 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/exons	MANE	Protein	UniProt
GCK	NM_000162.5	c.1268T>A	p.Phe423Tyr	missense_variant	10/10	ENST00000403799.8	NP_000153.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
GCK	ENST00000403799.8	c.1268T>A	p.Phe423Tyr	missense_variant	10/10	1	NM_000162.5	ENSP00000384247	P1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 33

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:2

Revision: reviewed by expert panel

Submissions by phenotype

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

Likely pathogenic, criteria provided, single submitter

clinical testing;curation

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

Aug 18, 2011

- -

Monogenic diabetes Pathogenic:1

Pathogenic, reviewed by expert panel

curation

ClinGen Monogenic Diabetes Variant Curation Expert Panel

Apr 27, 2024

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. -

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;.;.;.
MutationTaster	Benign	1.0	D;D;D;D
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;