7-44147738-C-T

Variant names:

• chr7-44147738-C-T
• rs1375656631
• NM_000162.5:c.775G>A

Variant summary

Our verdict is Pathogenic. The variant received 14 ACMG points: 14P and 0B. PM5_Supporting PP2 PP3 PM2_Supporting PP4_Moderate PS4 PP1_Strong

This summary comes from the ClinGen Evidence Repository: The c.775G>A variant in the glucokinase gene, GCK, causes an amino acid change of alanine to threonine at codon 259 (p.(Ala259Thr)) of NM_000162.5. This variant is predicted to be deleterious by computational evidence, with a REVEL score of 0.948, which is greater than the MDEP VCEP threshold of 0.70 (PP3) and is absent from gnomAD v2.1.1 (PM2_Supporting). 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). Another missense variant, c.776C>T, p.Ala259Val, has been classified as pathogenic by the ClinGen MDEP but has a greater Grantham distance than p.Ala259Thr (PM5_Supporting). This variant was identified in 12 unrelated individuals with hyperglycemia (PS4; internal lab contributors). Additionally, this variant segregated with diabetes/hyperglycemia, with 7 informative meioses in 6 families (PP1_Strong; 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 a 3-generation family history of diabetes) (PP4_Moderate; internal lab contributors). In summary, c.775G>A meets the criteria to be classified as pathogenic for monogenic diabetes. ACMG/AMP criteria applied, as specified by the ClinGen MDEP (specification version 1.3.0, approved 8/11/2023): PP3, PP2, PM5_Supporting, PS4, PP1_Strong, PP4_Moderate, PM2_Supporting. LINK:https://erepo.genome.network/evrepo/ui/classification/CA367400584/MONDO:0015967/086

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: GCK NM_000162.5 missense
• Clinical Significance: Pathogenic reviewed by expert panel P:5
• Conservation: PhyloP100: 7.83
• Publications: 17 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: Ambry Genetics, Genomics England PanelApp, Labcorp Genetics (formerly Invitae)
• 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

LOC105375258 (HGNC:):

ACMG classification

Specifications for GCK are available in the ClinGen Criteria Specification Registry and recommended for reference when assigning criteria.

Our verdict: Pathogenic. The variant received 14 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.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_000162.5. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	GCK	NM_000162.5	MANE Select	c.775G>A	p.Ala259Thr	missense	Exon 7 of 10	NP_000153.1	Q53Y25
	GCK	NM_033507.3		c.778G>A	p.Ala260Thr	missense	Exon 7 of 10	NP_277042.1	P35557-2
	GCK	NM_033508.3		c.772G>A	p.Ala258Thr	missense	Exon 8 of 11	NP_277043.1	P35557-3

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	GCK	ENST00000403799.8	TSL:1 MANE Select	c.775G>A	p.Ala259Thr	missense	Exon 7 of 10	ENSP00000384247.3	P35557-1
	GCK	ENST00000395796.8	TSL:1	n.*773G>A		non_coding_transcript_exon	Exon 8 of 11	ENSP00000379142.4	A0A8C8KJG0
	GCK	ENST00000395796.8	TSL:1	n.*773G>A		3_prime_UTR	Exon 8 of 11	ENSP00000379142.4	A0A8C8KJG0

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD2 exomes AF: 0.00000398 AC: 1 AN: 251056 AF XY: 0.00000736

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS 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: 6.84e-7 AC: 1 AN: 1461214 Hom.: 0 Cov.: 32 AF XY: 0.00000138 AC XY: 1 AN XY: 726938

African (AFR) AF: 0.00 AC: 0 AN: 33480

American (AMR) AF: 0.00 AC: 0 AN: 44724

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26134

East Asian (EAS) AF: 0.00 AC: 0 AN: 39700

South Asian (SAS) AF: 0.0000116 AC: 1 AN: 86256

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 52770

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5768

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1111990

Other (OTH) AF: 0.00 AC: 0 AN: 60392

GnomAD4 genome Cov.: 33

ClinVar

ClinVar submissions

Significance: Pathogenic

Revision: reviewed by expert panel

Pathogenic	VUS	Benign	Condition
2	-	-	Monogenic diabetes (2)
2	-	-	not provided (2)
1	-	-	Maturity-onset diabetes of the young type 2 (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.68
BayesDel_addAF	Pathogenic	0.46	D
BayesDel_noAF	Pathogenic	0.51
CADD	Pathogenic	30
DANN	Pathogenic	1.0
DEOGEN2	Pathogenic	0.94	D
Eigen	Pathogenic	0.70
Eigen_PC	Pathogenic	0.67
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Uncertain	0.97	D
M_CAP	Pathogenic	0.84	D
MetaRNN	Pathogenic	0.99	D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	3.6	H
PhyloP100		7.8
PrimateAI	Benign	0.47	T
PROVEAN	Uncertain	-3.5	D
REVEL	Pathogenic	0.90
Sift	Uncertain	0.0010	D
Sift4G	Pathogenic	0.0010	D
Polyphen		0.90	P
Vest4		0.94
MutPred		0.94		Loss of stability (P = 0.0611)
MVP		0.98
MPC		1.8
ClinPred		0.99	D
GERP RS		5.2
Varity_R		0.92
gMVP		0.99
Mutation Taster		=6/94	disease causing (ClinVar)

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: rs1375656631; hg19: chr7-44187337; COSMIC: COSV60787622; COSMIC: COSV60787622;