rs193922265

Positions:

• chr7-44145614-G-A
• chr7-44145614-G-C
• chr7-44145614-G-T

Variant summary

Our verdict is Likely pathogenic. Variant got 10 ACMG points: 10P and 0B. PS4_Moderate PM5_Supporting PP1_Moderate PP4_Moderate PP2 PP3 PM2_Supporting

This summary comes from the ClinGen Evidence Repository: The c.1136C>T variant in the glucokinase gene, GCK, causes an amino acid change of alanine to proline at codon 379 (p.(Ala379Val)) of NM_000162.5. GCK is defined by the ClinGen MDEP VCEP as a gene that has a low rate of benign missense variation and where pathogenic missense variants are a common mechanism of disease (PP2). This variant is predicted to be deleterious by computational evidence, with a REVEL score of 0.968, 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 five unrelated individuals with hyperglycemia (PS4_Moderate; PMID 18322640, 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; PMIDs: 18322640, 17573900). This variant segregated with diabetes, with three informative meioses in two families with MODY (PP1_Moderate; PMID 18322640). Another missense variant, c.1136C>A p.Ala379Glu, has been classified as pathogenic by the ClinGen MDEP VCEP but has a greater Grantham distance than p.Ala379Val (PM5_supporting). While studies exploring the effect of this variant on protein function have been performed, these studies do not meet the criteria set forth by the MDEP for the application of PS3 or BS3 (PMID:18322640). In summary, this variant meets the criteria to be classified as likely pathogenic for monogenic diabetes. ACMG/AMP criteria applied, as specified by the ClinGen MDEP VCEP (specification version 1.2.0, approved 6/7/2023): PP2, PP3, PM2_Supporting, PS4_Moderate, PP4_Moderate, PP1_Moderate, PM5_Supporting. LINK:https://erepo.genome.network/evrepo/ui/classification/CA367398790/MONDO:0015967/086

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0 (0 hom.)
  • Failed GnomAD Quality Control
• Consequence: GCK ENST00000403799.8 missense
• Clinical Significance: Likely pathogenic reviewed by expert panel P:3
• Conservation: PhyloP100: 8.02

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 10 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.
• PM5: 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.1136C>T	p.Ala379Val	missense_variant	9/10	ENST00000403799.8	NP_000153.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
GCK	ENST00000403799.8	c.1136C>T	p.Ala379Val	missense_variant	9/10	1	NM_000162.5	ENSP00000384247	P1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Data not reliable, filtered out with message: AC0 AF: 0.00 AC: 0 AN: 1454696 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 723696

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:3

Revision: reviewed by expert panel

Submissions by phenotype

not provided Pathogenic:2

Pathogenic, criteria provided, single submitter	clinical testing	GeneDx	Apr 28, 2022	Observed in patients with MODY in published literature (Estalella I et al., 2007; Weinert LS et al., 2014); Published functional studies demonstrate a damaging effect on enzyme activity (Estalella I et al., 2008); Not observed at significant frequency in large population cohorts (gnomAD); 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 (HGMD); This variant is associated with the following publications: (PMID: 28012402, 22389783, 22332836, 32375122, 25174781, 17573900, 18322640) -
Likely pathogenic, criteria provided, single submitter	clinical testing	Athena Diagnostics	Dec 10, 2018	Not found in the total gnomAD dataset, and the data is high quality (0/265258 chr). Found in at least one symptomatic patient. Predicted to have a damaging effect on the protein. Damaging to protein function(s) relevant to disease mechanism. -

Monogenic diabetes Pathogenic:1

Likely pathogenic, reviewed by expert panel

curation

ClinGen Monogenic Diabetes Variant Curation Expert Panel

Aug 01, 2023

The c.1136C>T variant in the glucokinase gene, GCK, causes an amino acid change of alanine to proline at codon 379 (p.(Ala379Val)) of NM_000162.5. GCK is defined by the ClinGen MDEP VCEP as a gene that has a low rate of benign missense variation and where pathogenic missense variants are a common mechanism of disease (PP2). This variant is predicted to be deleterious by computational evidence, with a REVEL score of 0.968, 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 five unrelated individuals with hyperglycemia (PS4_Moderate; PMID 18322640, 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; PMIDs: 18322640, 17573900). This variant segregated with diabetes, with three informative meioses in two families with MODY (PP1_Moderate; PMID 18322640). Another missense variant, c.1136C>A p.Ala379Glu, has been classified as pathogenic by the ClinGen MDEP VCEP but has a greater Grantham distance than p.Ala379Val (PM5_supporting). While studies exploring the effect of this variant on protein function have been performed, these studies do not meet the criteria set forth by the MDEP for the application of PS3 or BS3 (PMID: 18322640). In summary, this variant meets the criteria to be classified as likely pathogenic for monogenic diabetes. ACMG/AMP criteria applied, as specified by the ClinGen MDEP VCEP (specification version 1.2.0, approved 6/7/2023): PP2, PP3, PM2_Supporting, PS4_Moderate, PP4_Moderate, PP1_Moderate, PM5_Supporting. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.93
BayesDel_addAF	Pathogenic	0.58	D
BayesDel_noAF	Pathogenic	0.59
CADD	Pathogenic	31
DANN	Pathogenic	1.0
DEOGEN2	Pathogenic	0.82	.;D;D;.;.;.
Eigen	Pathogenic	0.83
Eigen_PC	Pathogenic	0.77
FATHMM_MKL	Pathogenic	0.97	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	1.0	D
MutationAssessor	Pathogenic	3.6	.;.;H;.;.;.
MutationTaster	Benign	1.0	D;D;D;D
PrimateAI	Uncertain	0.78	T
PROVEAN	Uncertain	-3.9	.;D;D;D;D;D
REVEL	Pathogenic	0.97
Sift	Pathogenic	0.0	.;D;D;D;D;D
Sift4G	Pathogenic	0.0010	D;D;D;D;D;D
Polyphen		1.0	D;.;D;D;D;D
Vest4		0.92
MutPred		0.98		.;.;Loss of disorder (P = 0.0728);.;.;.;
MVP		0.98
MPC		2.2
ClinPred		1.0	D
GERP RS		5.2
Varity_R		0.96
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: rs193922265; hg19: chr7-44185213; COSMIC: COSV56268757; COSMIC: COSV56268757;