rs794727839

Variant names:

• chr7-44147825-A-G
• rs794727839
• NM_000162.5:c.688T>C

Variant summary

Our verdict is Likely pathogenic. The variant received 6 ACMG points: 6P and 0B. PM5_Supporting PM1 PP2 PP3 PM2_Supporting

This summary comes from the ClinGen Evidence Repository: The c.688T>C variant in the glucokinase gene, GCK, causes an amino acid change of cysteine to arginine at codon 230 (p.(Cys230Arg)) 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 resides in an amino acid that directly binds glucose, which is defined as critical for the protein’s function by the ClinGen MDEP (PM1), and is predicted to be deleterious by computational evidence, with a REVEL score of 0.85, 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 three unrelated individuals with hyperglycemia; however, this does not meet the threshold set by the ClinGen MDEP for the application of PS4 (internal lab contributors). This variant was identified in an individual with a phenotype suggestive of GCK-hyperglycemia; however, the fasting blood sugar was slightly below the threshold for PP4 (5.5 mmol/L) (internal lab contributors). Another missense variant, c.689G>A p.Cys230Tyr, has been classified as pathogenic by the ClinGen MDEP but has a greater Grantham distance than p.Cys230Arg (PM5_Supporting). In summary, c.688T>C meets the criteria to be classified as likely pathogenic for monogenic diabetes. ACMG/AMP criteria applied, as specified by the ClinGen MDEP (specification version 1.3.0, approved 8/11/2023): PM1, PP2, PP3, PM2_Supporting, PM5_Supporting. LINK:https://erepo.genome.network/evrepo/ui/classification/CA247034/MONDO:0015967/086

• Frequency: Genomes: not found (cov: 33)
• Consequence: GCK NM_000162.5 missense
• Clinical Significance: Likely pathogenic reviewed by expert panel P:3 U:4 O:1
• Conservation: PhyloP100: 5.21
• 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: 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

ENSG00000300758 (HGNC:):

ACMG classification

Our verdict: Likely_pathogenic. The variant received 6 ACMG points.

• PM1: 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.
• PP2: For more information check the summary or visit ClinGen Evidence Repository.
• PP3: 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.688T>C	p.Cys230Arg	missense	Exon 7 of 10	NP_000153.1	Q53Y25
	GCK	NM_033507.3		c.691T>C	p.Cys231Arg	missense	Exon 7 of 10	NP_277042.1	P35557-2
	GCK	NM_033508.3		c.685T>C	p.Cys229Arg	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.688T>C	p.Cys230Arg	missense	Exon 7 of 10	ENSP00000384247.3	P35557-1
	GCK	ENST00000395796.8	TSL:1	n.*686T>C		non_coding_transcript_exon	Exon 8 of 11	ENSP00000379142.4	A0A8C8KJG0
	GCK	ENST00000395796.8	TSL:1	n.*686T>C		3_prime_UTR	Exon 8 of 11	ENSP00000379142.4	A0A8C8KJG0

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 33

ClinVar

ClinVar submissions

Significance: Likely pathogenic

Revision: reviewed by expert panel

Pathogenic	VUS	Benign	Condition
1	3	-	not provided (4)
-	1	-	Maturity-onset diabetes of the young (1)
1	-	-	Maturity-onset diabetes of the young type 2 (1)
1	-	-	Monogenic diabetes (1)
-	1	-	not specified (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.99
BayesDel_addAF	Pathogenic	0.49	D
BayesDel_noAF	Pathogenic	0.46
CADD	Uncertain	25
DANN	Benign	0.97
DEOGEN2	Uncertain	0.65	D
Eigen	Uncertain	0.52
Eigen_PC	Uncertain	0.51
FATHMM_MKL	Uncertain	0.93	D
LIST_S2	Benign	0.59	T
M_CAP	Pathogenic	0.63	D
MetaRNN	Pathogenic	0.97	D
MetaSVM	Pathogenic	1.0	D
MutationAssessor	Uncertain	2.4	M
PhyloP100		5.2
PrimateAI	Uncertain	0.71	T
PROVEAN	Benign	-1.1	N
REVEL	Pathogenic	0.85
Sift	Uncertain	0.021	D
Sift4G	Uncertain	0.0090	D
Polyphen		0.86	P
Vest4		0.91
MutPred		0.82		Gain of sheet (P = 0.0827)
MVP		0.99
MPC		2.6
ClinPred		0.96	D
GERP RS		5.3
Varity_R		0.98
gMVP		1.0
Mutation Taster		=1/99	disease causing

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: rs794727839; hg19: chr7-44187424;