7-44145227-A-T

Variant names:

• chr7-44145227-A-T
• rs193922278
• NM_000162.5:c.1307T>A

Variant summary

Our verdict is Pathogenic. The variant received 13 ACMG points: 13P and 0B. PS3_Supporting PM5_Supporting PP2 PP3 PM2_Supporting PP4_Moderate PS4_Moderate PP1_Strong

This summary comes from the ClinGen Evidence Repository: The c.1307T>A variant in the glucokinase gene, GCK, causes an amino acid change of isoleucine to asparagine at codon 436 (p.(Ile436Asn)) of NM_000162.5. 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 is also predicted to be deleterious by computational evidence, with a REVEL score of 0.957, which is greater than the MDEP VCEP threshold of 0.70 (PP3). This variant is absent in gnomAD v2.1.1 (PM2_Supporting), and was identified in at least 5 unrelated individuals with hyperglycemia (PS4_Moderate; PMID 17204055, PMID 20337973, PMID 22493702, internal lab contributors). At least 2 of these individuals have a clinical history highly specific for GCK-hyperglycemia (FBG 5.5-8 mmol/L and HbA1c 5.6 - 7.6% and negative antibodies +/- 2 hour oral glucose tolerance test increment <3 mmol/L) (PP4_Moderate; internal lab contributors). This variant also segregated with diabetes/hyperglycemia, with 4 informative meioses in 2 families (PP1_Strong; internal lab contributors). Another missense variant, c.1306A>T p.Ile436Phe has been interpreted as likely pathogenic by the ClinGen MDEP (PM5_Supporting). While the RAI of this variant was 0.975, this variant results in decreased inhibition by GKRP (PS3_Supporting; PMID:22493702). In summary, this evidence supports the classification of c.1307T>A as pathogenic for monogenic diabetes. ACMG/AMP criteria applied, as specified by the ClinGen MDEP (specification version 1.3.0, approved 8/11/2023): PP1_Strong, PS4_Moderate, PP4_Moderate, PM5_Supporting, PP2, PP3, PM2_Supporting. LINK:https://erepo.genome.network/evrepo/ui/classification/CA213751/MONDO:0015967/086

• Frequency: Genomes: not found (cov: 33)
• Consequence: GCK NM_000162.5 missense
• Clinical Significance: Pathogenic reviewed by expert panel P:3
• Conservation: PhyloP100: 8.79
• Publications: 5 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 13 ACMG points.

• PS3: 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.
• 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.1307T>A	p.Ile436Asn	missense	Exon 10 of 10	NP_000153.1
	GCK	NM_033507.3		c.1310T>A	p.Ile437Asn	missense	Exon 10 of 10	NP_277042.1
	GCK	NM_033508.3		c.1304T>A	p.Ile435Asn	missense	Exon 11 of 11	NP_277043.1

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	GCK	ENST00000403799.8	TSL:1 MANE Select	c.1307T>A	p.Ile436Asn	missense	Exon 10 of 10	ENSP00000384247.3
	GCK	ENST00000395796.8	TSL:1	n.*1305T>A		non_coding_transcript_exon	Exon 11 of 11	ENSP00000379142.4
	GCK	ENST00000459642.1	TSL:1	n.687T>A		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
1	-	-	Maturity-onset diabetes of the young type 2 (1)
1	-	-	Monogenic diabetes (1)
1	-	-	not provided (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.94
BayesDel_addAF	Pathogenic	0.45	D
BayesDel_noAF	Pathogenic	0.41
CADD	Pathogenic	33
DANN	Uncertain	0.99
DEOGEN2	Uncertain	0.76	D
Eigen	Pathogenic	0.98
Eigen_PC	Pathogenic	0.92
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Uncertain	0.97	D
M_CAP	Pathogenic	0.85	D
MetaRNN	Pathogenic	0.99	D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	3.5	M
PhyloP100		8.8
PrimateAI	Pathogenic	0.80	T
PROVEAN	Pathogenic	-5.9	D
REVEL	Pathogenic	0.96
Sift	Uncertain	0.0010	D
Sift4G	Uncertain	0.0030	D
Polyphen		1.0	D
Vest4		0.95
MutPred		0.94		Gain of disorder (P = 0.0117)
MVP		0.98
MPC		2.9
ClinPred		1.0	D
GERP RS		5.8
Varity_R		0.99
gMVP		1.0
Mutation Taster		=1/99	disease causing (ClinVar)

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		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: rs193922278; hg19: chr7-44184826;