rs193922283

Positions:

• chr7-44145176-G-A

Variant summary

Our verdict is Pathogenic. Variant got 16 ACMG points: 16P and 0B. PM1 PM2 PP3_Strong PP5_Very_Strong

The NM_000162.5(GCK):​c.1358C>T​(p.Ser453Leu) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000137 in 1,458,166 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Likely pathogenic (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. S453W) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: GCK NM_000162.5 missense
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:5
• Conservation: PhyloP100: 9.43

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]

ACMG classification

Verdict is Pathogenic. Variant got 16 ACMG points.

• PM1: In a hotspot region, there are 6 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 1 benign, 2 uncertain in NM_000162.5
• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.989
• PP5: Variant 7-44145176-G-A is Pathogenic according to our data. Variant chr7-44145176-G-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 36200.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
GCK	NM_000162.5	c.1358C>T	p.Ser453Leu	missense_variant	10/10	ENST00000403799.8

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
GCK	ENST00000403799.8	c.1358C>T	p.Ser453Leu	missense_variant	10/10	1	NM_000162.5	P1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1458166 Hom.: 0 Cov.: 31 AF XY: 0.00000138 AC XY: 1 AN XY: 725344

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000180

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:5

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Pathogenic:2

Likely pathogenic, criteria provided, single submitter	clinical testing	Athena Diagnostics	Feb 04, 2020	Not found in the total gnomAD dataset, and the data is high quality. Found in at least one patient with expected phenotype for this gene. Predicted to have a damaging effect on the protein. Assessment of experimental evidence suggests this variant results in abnormal protein function. -
Pathogenic, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Nov 30, 2021	This missense change has been observed in individual(s) with autosomal dominant maturity-onset diabetes of the young (PMID: 14517956, 16731834, 18399931; Invitae). In at least one individual the variant was observed to be de novo. For these reasons, this variant has been classified as Pathogenic. Experimental studies have shown that this missense change affects GCK function (PMID: 16731834). Algorithms developed to predict the effect of missense changes on protein structure and function (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be disruptive. ClinVar contains an entry for this variant (Variation ID: 36200). This variant is not present in population databases (gnomAD no frequency). This sequence change replaces serine, which is neutral and polar, with leucine, which is neutral and non-polar, at codon 453 of the GCK protein (p.Ser453Leu). -

Type 2 diabetes mellitus;C0342277:Maturity-onset diabetes of the young type 2;C1833104:Permanent neonatal diabetes mellitus;C1865290:Hyperinsulinism due to glucokinase deficiency Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Fulgent Genetics, Fulgent Genetics

Oct 31, 2018

- -

Maturity-onset diabetes of the young type 2 Pathogenic:1

Likely pathogenic, criteria provided, single submitter

research

Geisinger Clinic, Geisinger Health System

Aug 02, 2022

PM2, PP3, PP1, PS4_Supporting, PM5_Supporting, PP4, PP2, PS3_Supporting -

Monogenic diabetes Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Jun 09, 2022

Variant summary: GCK c.1358C>T (p.Ser453Leu) results in a non-conservative amino acid change located in the Hexokinase, C-terminal domain (IPR022673) of the encoded protein sequence. Five of five in-silico tools predict a damaging effect of the variant on protein function. The variant was absent in 240536 control chromosomes (gnomAD). c.1358C>T has been reported in the literature in individuals affected with Monogenic Diabetes (examples: Sagen_2008 and Thomson_2003). These data indicate that the variant is likely to be associated with disease. Sagen et al (2006) have shown that this missense change affects GCK function. Three clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014 and classified the variant as pathogenic (n=1) and likely pathogenic (n=2). Based on the evidence outlined above, the variant was classified as likely pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.76
BayesDel_addAF	Pathogenic	0.53	D
BayesDel_noAF	Pathogenic	0.53
CADD	Pathogenic	32
DANN	Pathogenic	1.0
DEOGEN2	Uncertain	0.51	.;D;D;.;.;.
Eigen	Pathogenic	0.73
Eigen_PC	Pathogenic	0.69
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Pathogenic	0.98	D;D;D;.;D;D
M_CAP	Pathogenic	0.72	D
MetaRNN	Pathogenic	0.99	D;D;D;D;D;D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Uncertain	2.0	.;.;M;.;.;.
MutationTaster	Benign	1.0	D;D;D;D
PrimateAI	Uncertain	0.74	T
PROVEAN	Uncertain	-2.6	.;D;N;N;N;N
REVEL	Pathogenic	0.82
Sift	Uncertain	0.0010	.;D;D;D;D;D
Sift4G	Uncertain	0.0040	D;D;D;D;D;D
Polyphen		1.0	D;.;D;D;D;D
Vest4		0.88
MutPred		0.94		.;.;Loss of catalytic residue at S453 (P = 0.0109);.;.;.;
MVP		0.99
MPC		2.0
ClinPred		0.99	D
GERP RS		5.8
Varity_R		0.92
gMVP		0.99

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

LitVar

Other links and lift over

dbSNP: rs193922283; hg19: chr7-44184775;