7-44147764-C-T

Position:

• chr7-44147764-C-T

Variant summary

Our verdict is Likely pathogenic. Variant got 6 ACMG points: 6P and 0B. PM5_Supporting PP4_Moderate PM2_Supporting PP2 PP3

This summary comes from the ClinGen Evidence Repository: The c.749G>A variant in the glucokinase gene, GCK, causes an amino acid change of arginine to histidine at codon 250 (p.(Arg250His)) of NM_000162.5. This variant was identified in an individual with a clinical history highly specific for GCK-hyperglycemia (pediatric patient with incidental diagnosis with FBG 5.5-8 mmol/L and HbA1c 5.6 - 7.6% persistently and negative antibodies (PP4_Moderate; PMID:28170077, 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). 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 has an incomputable gnomAD v2.1.1 Popmax minor filtering allele frequency due to 0 copies in the European non-Finnish subpopulation and 1 copy in the African/African American subpopulation, thereby meeting the ClinGen MDEP threshold criteria for PM2_Supporting (ENF Popmax FAF <= 0.000003 and <= 2 copies in ENF and <=1 copy in any other subpopulation) (PM2_Supporting). Another missense variant, c.748C>T p.Arg250Cys, has been classified as pathogenic by the ClinGen MDEP but has a greater Grantham distance than p.Arg250His (PM5_Supporting). The relative activity index (RAI) of this variant was above the MDEP cutoff of 0.5, and thermostability was not evaluated, and neither PS3 nor BS3 could be applied (PMID:30592380). In summary, c.749G>A meets the criteria to be classified as likely pathogenic for monogenic diabetes. ACMG/AMP criteria applied, as specified by the ClinGen MDEP (specification version 1.3, approved 8/11/2023): PP4_Moderate, PP2, PP3, PM2_Supporting, PM5_Supporting. LINK:https://erepo.genome.network/evrepo/ui/classification/CA4239531/MONDO:0015967/086

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: GCK NM_000162.5 missense
• Clinical Significance: Likely pathogenic reviewed by expert panel P:1 U:1
• Conservation: PhyloP100: 7.86

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 Likely_pathogenic. Variant got 6 ACMG points.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
GCK	NM_000162.5	c.749G>A	p.Arg250His	missense_variant	7/10	ENST00000403799.8
LOC105375258	XR_927223.3	n.98+16C>T		intron_variant, non_coding_transcript_variant

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
GCK	ENST00000403799.8	c.749G>A	p.Arg250His	missense_variant	7/10	1	NM_000162.5	P1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD3 exomes AF: 0.00000398 AC: 1 AN: 251152 Hom.: 0 AF XY: 0.00 AC XY: 0 AN XY: 135860

Gnomad AFR exome AF: 0.0000616

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1461282 Hom.: 0 Cov.: 32 AF XY: 0.00000138 AC XY: 1 AN XY: 726972

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.0000252

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 8.99e-7

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

ESP6500AA AF: 0.000227 AC: 1

ESP6500EA AF: 0.00 AC: 0

ExAC AF: 0.00000824 AC: 1

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:1 Uncertain:1

Revision: reviewed by expert panel

Submissions by phenotype

Monogenic diabetes Pathogenic:1

Likely pathogenic, reviewed by expert panel

curation

ClinGen Monogenic Diabetes Variant Curation Expert Panel

Oct 25, 2023

The c.749G>A variant in the glucokinase gene, GCK, causes an amino acid change of arginine to histidine at codon 250 (p.(Arg250His)) of NM_000162.5. This variant was identified in an individual with a clinical history highly specific for GCK-hyperglycemia (pediatric patient with incidental diagnosis with FBG 5.5-8 mmol/L and HbA1c 5.6 - 7.6% persistently and negative antibodies (PP4_Moderate; PMID: 28170077, 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). 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 has an incomputable gnomAD v2.1.1 Popmax minor filtering allele frequency due to 0 copies in the European non-Finnish subpopulation and 1 copy in the African/African American subpopulation, thereby meeting the ClinGen MDEP threshold criteria for PM2_Supporting (ENF Popmax FAF <= 0.000003 and <= 2 copies in ENF and <=1 copy in any other subpopulation) (PM2_Supporting). Another missense variant, c.748C>T p.Arg250Cys, has been classified as pathogenic by the ClinGen MDEP but has a greater Grantham distance than p.Arg250His (PM5_Supporting). The relative activity index (RAI) of this variant was above the MDEP cutoff of 0.5, and thermostability was not evaluated, and neither PS3 nor BS3 could be applied (PMID: 30592380). In summary, c.749G>A meets the criteria to be classified as likely pathogenic for monogenic diabetes. ACMG/AMP criteria applied, as specified by the ClinGen MDEP (specification version 1.3, approved 8/11/2023): PP4_Moderate, PP2, PP3, PM2_Supporting, PM5_Supporting. -

not specified Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Genetic Services Laboratory, University of Chicago

May 30, 2017

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.21
BayesDel_addAF	Pathogenic	0.22	D
BayesDel_noAF	Pathogenic	0.25
CADD	Pathogenic	34
DANN	Pathogenic	1.0
DEOGEN2	Pathogenic	0.81	.;D;.;.;.
Eigen	Uncertain	0.49
Eigen_PC	Uncertain	0.55
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Uncertain	0.93	D;D;.;D;D
M_CAP	Pathogenic	0.29	D
MetaRNN	Pathogenic	0.93	D;D;D;D;D
MetaSVM	Pathogenic	0.85	D
MutationAssessor	Benign	1.7	.;L;.;.;.
MutationTaster	Benign	1.0	D;D;D;D
PrimateAI	Uncertain	0.71	T
PROVEAN	Uncertain	-3.6	.;D;D;D;D
REVEL	Pathogenic	0.87
Sift	Benign	0.22	.;T;T;T;T
Sift4G	Benign	0.15	T;T;T;T;T
Polyphen		1.0	D;D;D;B;.
Vest4		0.87
MVP		0.97
MPC		2.4
ClinPred		0.98	D
GERP RS		5.3
Varity_R		0.66
gMVP		0.98

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: rs370375148; hg19: chr7-44187363;