7-44145136-T-A

Position:

• chr7-44145136-T-A

Variant summary

Our verdict is Pathogenic. Variant got 11 ACMG points: 11P and 0B. PM2_Supporting PVS1 PP4_Moderate

This summary comes from the ClinGen Evidence Repository: The c.1398A>T variant in the glucokinase gene, GCK, causes a change from the stop codon to cysteine in the final exon (10/10), resulting in the addition of 144 amino acids at the end of the protein (p.(Ter466CysextTer144)). This variant, located in exon 10 of 10, is predicted to cause loss of a stop codon and result in an elongated protein. The additional residues are expected to cause improper folding, resulting in loss of function in a gene in which loss-of-function is an established disease mechanism (PVS1; PMID 19790256). 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 increment < 3 mmol/L and negative antibodies) (PP4_Moderate; internal lab contributors). This variant is absent from gnomAD v2.1.1 (PM2_Supporting). This variant segregated with hyperglycemia with two informative meioses in a single family; however, this does not meet the thresholds for PP1 set by the ClinGen MDEP (PMID:27236918, internal lab contributors). In summary, c.1398A>T meets the criteria to be classified as pathogenic for monogenic diabetes. ACMG/AMP criteria applied, as specified by the ClinGen MDEP (specification version 1.2.0, approved 6/7/2023): PVS1, PP4_Moderate, PM2_Supporting. LINK:https://erepo.genome.network/evrepo/ui/classification/CA367396714/MONDO:0015967/086

• Frequency: Genomes: not found (cov: 33)
• Consequence: GCK NM_000162.5 stop_lost
• Clinical Significance: Pathogenic reviewed by expert panel P:1
• Conservation: PhyloP100: 3.31

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]

GCK (HGNC:):

ACMG classification

Verdict is Pathogenic. Variant got 11 ACMG points.

• PVS1: For more information check the summary or visit ClinGen Evidence Repository.
• PM2: 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.1398A>T	p.Ter466Cysext*?	stop_lost	10/10	ENST00000403799.8	NP_000153.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
GCK	ENST00000403799.8	c.1398A>T	p.Ter466Cysext*?	stop_lost	10/10	1	NM_000162.5	ENSP00000384247.3

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 33

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:1

Revision: reviewed by expert panel

Submissions by phenotype

Monogenic diabetes Pathogenic:1

Pathogenic, reviewed by expert panel

curation

ClinGen Monogenic Diabetes Variant Curation Expert Panel

Jan 02, 2024

The c.1398A>T variant in the glucokinase gene, GCK, causes a change from the stop codon to cysteine in the final exon (10/10), resulting in the addition of 144 amino acids at the end of the protein (p.(Ter466CysextTer144)). This variant, located in exon 10 of 10, is predicted to cause loss of a stop codon and result in an elongated protein. The additional residues are expected to cause improper folding, resulting in loss of function in a gene in which loss-of-function is an established disease mechanism (PVS1; PMID 19790256). 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 increment < 3 mmol/L and negative antibodies) (PP4_Moderate; internal lab contributors). This variant is absent from gnomAD v2.1.1 (PM2_Supporting). This variant segregated with hyperglycemia with two informative meioses in a single family; however, this does not meet the thresholds for PP1 set by the ClinGen MDEP (PMID: 27236918, internal lab contributors). In summary, c.1398A>T meets the criteria to be classified as pathogenic for monogenic diabetes. ACMG/AMP criteria applied, as specified by the ClinGen MDEP (specification version 1.2.0, approved 6/7/2023): PVS1, PP4_Moderate, PM2_Supporting. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Uncertain	0.024	T
BayesDel_noAF	Benign	-0.20
CADD	Benign	17
DANN	Benign	0.84
Eigen	Uncertain	0.61
Eigen_PC	Uncertain	0.42
FATHMM_MKL	Uncertain	0.96	D
MutationTaster	Benign	1.0	N;N;N;N
Vest4		0.30
GERP RS		4.6

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

No publications associated with this variant yet.

Other links and lift over

hg19: chr7-44184735;