chr7-44147711-C-T

Position:

• chr7-44147711-C-T

Variant summary

Our verdict is Pathogenic. Variant got 13 ACMG points: 13P and 0B. PM2_Supporting PS4 PP1_Strong PP4_Moderate PP2 PP3

This summary comes from the ClinGen Evidence Repository: The c.802G>A variant in the glucokinase gene, GCK, causes an amino acid change of glutamic acid to lysine at codon 268 (p.(Glu268Lys)) of NM_000162.5. This variant segregated with diabetes/hyperglycemia, with four informative meioses in two families (PP1_Strong; internal lab contributors). This variant is absent from gnomAD v2.1.1 (PM2_Supporting). This variant was identified in eight unrelated individuals with hyperglycemia (PS4; internal lab contributors). 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). 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 0.727, which is greater than the MDEP VCEP threshold of 0.70 (PP3). In summary, c.802G>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): PP1_Strong, PS4, PP4_Moderate, PP2, PP3, PM2_Supporting. LINK:https://erepo.genome.network/evrepo/ui/classification/CA367400529/MONDO:0015967/086

• Frequency: Genomes: not found (cov: 33)
• Consequence: GCK NM_000162.5 missense
• Clinical Significance: Pathogenic reviewed by expert panel P:1 U:3 O:1
• Conservation: PhyloP100: 7.83

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]

LOC105375258 (HGNC:):

ACMG classification

Verdict is Pathogenic. Variant got 13 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.802G>A	p.Glu268Lys	missense_variant	7/10	ENST00000403799.8	NP_000153.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
GCK	ENST00000403799.8	c.802G>A	p.Glu268Lys	missense_variant	7/10	1	NM_000162.5	ENSP00000384247.3

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 33

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:1 Uncertain:3 Other:1

Revision: reviewed by expert panel

Submissions by phenotype

not provided Uncertain:3

Uncertain significance, criteria provided, single submitter	clinical testing	Revvity Omics, Revvity	Aug 09, 2023	- -
Uncertain significance, criteria provided, single submitter	clinical testing	Athena Diagnostics	Jan 11, 2023	Available data are insufficient to determine the clinical significance of the variant at this time. This variant has been identified in at least one individual with clinical features associated with this gene. This variant has not been reported in large, multi-ethnic general populations. (http://gnomad.broadinstitute.org) Computational tools disagree on the variant's effect on normal protein function. -
Uncertain significance, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Sep 24, 2021	In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. Algorithms developed to predict the effect of missense changes on protein structure and function are either unavailable or do not agree on the potential impact of this missense change (SIFT: "Deleterious"; PolyPhen-2: "Benign"; Align-GVGD: "Class C15"). ClinVar contains an entry for this variant (Variation ID: 447420). This variant has been observed in individual(s) with autosomal dominant maturity-onset diabetes of the young (PMID: 19790256, 25555642). This variant is not present in population databases (ExAC no frequency). This sequence change replaces glutamic acid with lysine at codon 268 of the GCK protein (p.Glu268Lys). The glutamic acid residue is highly conserved and there is a small physicochemical difference between glutamic acid and lysine. -

Monogenic diabetes Pathogenic:1

Pathogenic, reviewed by expert panel

curation

ClinGen Monogenic Diabetes Variant Curation Expert Panel

Oct 05, 2023

The c.802G>A variant in the glucokinase gene, GCK, causes an amino acid change of glutamic acid to lysine at codon 268 (p.(Glu268Lys)) of NM_000162.5. This variant segregated with diabetes/hyperglycemia, with four informative meioses in two families (PP1_Strong; internal lab contributors). This variant is absent from gnomAD v2.1.1 (PM2_Supporting). This variant was identified in eight unrelated individuals with hyperglycemia (PS4; internal lab contributors). 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). 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 0.727, which is greater than the MDEP VCEP threshold of 0.70 (PP3). In summary, c.802G>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): PP1_Strong, PS4, PP4_Moderate, PP2, PP3, PM2_Supporting. -

Maturity onset diabetes mellitus in young Other:1

Uncertain risk allele, criteria provided, single submitter

research

Clinical Genomics, Uppaluri K&H Personalized Medicine Clinic

-

Potent mutations in GCK gene is associated with poor secretion of insulin. Its associated with milder forms of diabetes, which can be controlled by diet . However, there is no sufficient evidence to ascertain the significance of rs1554335111 in MODY, yet. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.22
BayesDel_addAF	Pathogenic	0.41	D
BayesDel_noAF	Pathogenic	0.35
CADD	Pathogenic	28
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.71	.;D;.;.;.
Eigen	Benign	0.16
Eigen_PC	Uncertain	0.34
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Uncertain	0.92	D;D;.;D;D
M_CAP	Pathogenic	0.37	D
MetaRNN	Pathogenic	0.91	D;D;D;D;D
MetaSVM	Uncertain	0.70	D
MutationAssessor	Uncertain	2.3	.;M;.;.;.
PrimateAI	Uncertain	0.68	T
PROVEAN	Uncertain	-2.4	.;N;N;N;N
REVEL	Pathogenic	0.73
Sift	Benign	0.29	.;T;T;T;T
Sift4G	Benign	0.30	T;T;T;T;T
Polyphen		0.30	B;B;B;B;.
Vest4		0.67
MutPred		0.88		.;Gain of methylation at E268 (P = 0.0287);.;.;.;
MVP		0.92
MPC		1.3
ClinPred		0.94	D
GERP RS		5.5
Varity_R		0.79
gMVP		0.99

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: rs1554335111; hg19: chr7-44187310; COSMIC: COSV105207673; COSMIC: COSV105207673;