chr7-44145189-CG-C

Variant names:

• chr7-44145189-CG-C
• rs1057524901
• NM_000162.5:c.1344delC

Variant summary

Our verdict is Pathogenic. The variant received 15 ACMG points: 15P and 0B. PP1_Moderate PM2_Supporting PVS1 PP4_Moderate PS4_Moderate

This summary comes from the ClinGen Evidence Repository: The c.1344del variant in the glucokinase gene, GCK, causes a frameshift in the protein at codon 449 (NM_000162.5), adding 165 novel amino acids before encountering a stop codon (p.(p.Ala449ArgfsTer165)). 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 is absent from gnomAD v2.1.1 (PM2_Supporting). This variant was identified in five unrelated individuals with a clinical picture consistent with non-autoimmune/insulin-deficient diabetes (PS4_Moderate; ClinVar ID 393448, internal lab contributors). This variant segregated with disease, with 3 informative meioses in 2 families with MODY (PP1_Moderate; internal lab contributors). This variant was identified in an individual with a clinical history highly specific for GCK-MODY (FBG 5.5-8 mmol/L and HbA1c 5.6 - 7.6% and negative antibodies)(PP4_Moderate, internal lab contributor). In summary, the c.1344del variant 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, PP1_Moderate, PP4_Moderate, PS4_Moderate, PM2_Supporting). LINK:https://erepo.genome.network/evrepo/ui/classification/CA16609265/MONDO:0015967/086

• Frequency: Genomes: not found (cov: 33)
• Consequence: GCK NM_033507.3 frameshift
• Clinical Significance: Pathogenic reviewed by expert panel P:3
• Conservation: PhyloP100: -2.28
• Publications: 1 publications found

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 Gene-Disease associations (from GenCC):

• hyperinsulinism due to glucokinase deficiency

  Inheritance: AD Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Genomics England PanelApp, Labcorp Genetics (formerly Invitae), Ambry Genetics, Orphanet
• maturity-onset diabetes of the young type 2

  Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: Labcorp Genetics (formerly Invitae), Genomics England PanelApp, Ambry Genetics
• monogenic diabetes

  Inheritance: AD Classification: DEFINITIVE Submitted by: ClinGen
• diabetes mellitus, noninsulin-dependent

  Inheritance: AD Classification: STRONG Submitted by: Genomics England PanelApp
• permanent neonatal diabetes mellitus 1

  Inheritance: AR Classification: STRONG, MODERATE Submitted by: Genomics England PanelApp, Labcorp Genetics (formerly Invitae), Ambry Genetics
• transient neonatal diabetes mellitus

  Inheritance: AR Classification: STRONG Submitted by: Genomics England PanelApp
• maturity-onset diabetes of the young

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• permanent neonatal diabetes mellitus

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Pathogenic. The variant received 15 ACMG points.

• PVS1: For more information check the summary or visit ClinGen Evidence Repository.
• 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.
• PP4: For more information check the summary or visit ClinGen Evidence Repository.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_033507.3. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	GCK	NM_000162.5	MANE Select	c.1344delC	p.Ala449ArgfsTer165	frameshift	Exon 10 of 10	NP_000153.1
	GCK	NM_033507.3		c.1347delC	p.Ala450ArgfsTer165	frameshift	Exon 10 of 10	NP_277042.1
	GCK	NM_033508.3		c.1341delC	p.Ala448ArgfsTer165	frameshift	Exon 11 of 11	NP_277043.1

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	GCK	ENST00000403799.8	TSL:1 MANE Select	c.1344delC	p.Ala449ArgfsTer165	frameshift	Exon 10 of 10	ENSP00000384247.3
	GCK	ENST00000395796.8	TSL:1	n.*1342delC		non_coding_transcript_exon	Exon 11 of 11	ENSP00000379142.4
	GCK	ENST00000459642.1	TSL:1	n.724delC		non_coding_transcript_exon	Exon 2 of 2

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 33

ClinVar

ClinVar submissions as Germline

Significance: Pathogenic

Revision: reviewed by expert panel

Pathogenic	VUS	Benign	Condition
2	-	-	Monogenic diabetes (2)
1	-	-	not provided (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
PhyloP100		-2.3

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

Other links and lift over

dbSNP: rs1057524901; hg19: chr7-44184788;