rs193922258

Positions:

• chr7-44145731-C-G
• chr7-44145731-C-T

Variant summary

Our verdict is Pathogenic. Variant got 10 ACMG points: 10P and 0B. PVS1 PM2_Supporting PS1_Supporting

This summary comes from the ClinGen Evidence Repository: The c.1020-1G>C variant in the glucokinase gene, GCK, is predicted to remove a canonical splice acceptor site in intron 8 of NM_000162.5. This variant is predicted to cause skipping of biologically-relevant exon 9 of 10, resulting in deletion of >10% of a protein encoded by a gene in which loss-of-function is an established disease mechanism (PVS1; PMID:19790256). This variant is absent from gnomAD v2.1.1 (PM2_Supporting). This variant was identified in one individual with hyperglycemia; however, PS4_Moderate cannot be applied because this number is below the ClinGen MDEP threshold (PMID:18248649). The c.1020G>A variant at the same canonical nucleotide has been classified as pathogenic for monogenic diabetes by the ClinGen MDEP, and c.1020G>C has a similar predicted impact by Splice AI (0.99 and 0.99 for Acceptor Loss) (PS1_Supporting). In summary, c.1020-1G>C meets the criteria to be classified as pathogenic for monogenic diabetes. ACMG/AMP criteria applied, as specified by the ClinGen MDEP VCEP (specification version 1.3.0; approved 8/11/2023): PVS1, PM2_Supporting, PS1_Supporting.  LINK:https://erepo.genome.network/evrepo/ui/classification/CA213704/MONDO:0015967/086

• Frequency: Genomes: not found (cov: 33)
• Consequence: GCK NM_000162.5 splice_acceptor
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Pathogenic reviewed by expert panel P:2
• Conservation: PhyloP100: 6.04

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 10 ACMG points.

• PVS1: For more information check the summary or visit ClinGen Evidence Repository.
• PS1: For more information check the summary or visit ClinGen Evidence Repository.
• PM2: 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.1020-1G>C		splice_acceptor_variant		ENST00000403799.8	NP_000153.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
GCK	ENST00000403799.8	c.1020-1G>C		splice_acceptor_variant		1	NM_000162.5	ENSP00000384247	P1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 32

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

Mar 31, 2024

The c.1020-1G>C variant in the glucokinase gene, GCK, is predicted to remove a canonical splice acceptor site in intron 8 of NM_000162.5. This variant is predicted to cause skipping of biologically-relevant exon 9 of 10, resulting in deletion of >10% of a protein encoded by a gene in which loss-of-function is an established disease mechanism (PVS1; PMID: 19790256). This variant is absent from gnomAD v2.1.1 (PM2_Supporting). This variant was identified in one individual with hyperglycemia; however, PS4_Moderate cannot be applied because this number is below the ClinGen MDEP threshold (PMID: 18248649). The c.1020G>A variant at the same canonical nucleotide has been classified as pathogenic for monogenic diabetes by the ClinGen MDEP, and c.1020G>C has a similar predicted impact by Splice AI (0.99 and 0.99 for Acceptor Loss) (PS1_Supporting). In summary, c.1020-1G>C meets the criteria to be classified as pathogenic for monogenic diabetes. ACMG/AMP criteria applied, as specified by the ClinGen MDEP VCEP (specification version 1.3.0; approved 8/11/2023): PVS1, PM2_Supporting, PS1_Supporting. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Pathogenic	0.24
CADD	Pathogenic	34
DANN	Uncertain	0.99
Eigen	Pathogenic	0.96
Eigen_PC	Pathogenic	0.78
FATHMM_MKL	Pathogenic	0.98	D
MutationTaster	Benign	1.0	D;D;D;D
GERP RS		4.3

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.91
SpliceAI score (max)		0.99		Details are displayed if max score is > 0.2
DS_AG_spliceai		0.66		Position offset: -23
DS_AL_spliceai		0.99		Position offset: -1

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

LitVar

Other links and lift over

dbSNP: rs193922258; hg19: chr7-44185330;