rs193922268

chr7-44145593-A-G

Variant summary

Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PM1 PM2 PM5 PP3_Strong PP5_Very_Strong

The NM_000162.5(GCK):c.1157T>C(p.Leu386Pro) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000000688 in 1,453,796 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 12/21 in silico tools predict a damaging outcome for this variant. Variant has been reported in ClinVar as Pathogenic (★★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. L386R) has been classified as Likely pathogenic.

• Frequency:
  • Genomes: not found (cov: 34)
  • Exomes 𝑓: 6.9e-7 (0 hom.)
• Consequence: GCK NM_000162.5 missense
• Clinical Significance: Pathogenic reviewed by expert panel P:3 U:2
• Conservation: PhyloP100: 9.24

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 18 ACMG points.

• PM1: In a hotspot region, there are 15 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 5 uncertain in NM_000162.5
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr7-44145593-A-C is described in ClinVar as [Likely_pathogenic]. Clinvar id is 3233999.Status of the report is reviewed_by_expert_panel, 3 stars.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.987
• PP5: Variant 7-44145593-A-G is Pathogenic according to our data. Variant chr7-44145593-A-G is described in ClinVar as [Pathogenic]. Clinvar id is 36180.Status of the report is reviewed_by_expert_panel, 3 stars. Variant chr7-44145593-A-G is described in Lovd as [Likely_pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
GCK	NM_000162.5	c.1157T>C	p.Leu386Pro	missense_variant	9/10	ENST00000403799.8

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
GCK	ENST00000403799.8	c.1157T>C	p.Leu386Pro	missense_variant	9/10	1	NM_000162.5	P1

Frequencies

GnomAD3 genomes Cov.: 34

GnomAD4 exome AF: 6.88e-7 AC: 1 AN: 1453796 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 723104

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: 9.01e-7

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 34

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:3 Uncertain:2

Revision: reviewed by expert panel

Submissions by phenotype

not provided Pathogenic:1 Uncertain:1

Uncertain significance, criteria provided, single submitter	clinical testing	Invitae	Feb 23, 2023	This sequence change replaces leucine, which is neutral and non-polar, with proline, which is neutral and non-polar, at codon 386 of the GCK protein (p.Leu386Pro). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with GCK-related conditions. ClinVar contains an entry for this variant (Variation ID: 36180). Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is expected to disrupt GCK protein function. In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. -
Likely pathogenic, criteria provided, single submitter	clinical testing	Athena Diagnostics	Nov 04, 2022	This variant has been identified in at least one individual with clinical features associated with MODY, including a de novo case. This variant has not been reported in large, multi-ethnic general populations (http://gnomad.broadinstitute.org). Computational tools predict that this variant is damaging. -

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

Likely pathogenic, criteria provided, single submitter

clinical testing;curation

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

Aug 18, 2011

- -

Monogenic diabetes Pathogenic:1

Pathogenic, reviewed by expert panel

curation

ClinGen Monogenic Diabetes Variant Curation Expert Panel

Apr 28, 2024

The c.1157T>C variant in the glucokinase gene, GCK, causes an amino acid change of leucine to proline at codon 286 (p.(Leu386Pro)) 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 predicted to be deleterious by computational evidence, with a REVEL score of 0.984, which is greater than the MDEP VCEP threshold of 0.70 (PP3). This variant is absent from gnomAD v2.1.1 (PM2_Supporting). This variant was identified as a de novo occurrence with confirmed parental relationships in 1 individual with a clinical picture highly specific for GCK-hyperglycemia (FBG 5.5-8 mmol/L and HbA1c 5.6-7.6 and negative antibodies) (PP4_Moderate, PS2; internal lab contributors). Another missense variant, c.1156C>G, p.(Leu386Val) has been interpreted as pathogenic by the ClinGen MDEP, and p.(Leu386Pro) has a greater Grantham distance (PM5). In summary, c.1157T>C 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): PS2, PP4_Moderate, PM2_supporting, PP2, PP3, PM5. -

Maturity onset diabetes mellitus in young Uncertain:1

Uncertain significance, criteria provided, single submitter

research

Clinical Genomics, Uppaluri K&H Personalized Medicine Clinic

-

Potent mutations in GCK gene is associated with poor secretion of insulin. Its associated with milder forms of diabetes, which can be controlled by diet well. However, there is no sufficient evidence to assertain the significance of rs193922268 in MODY, yet. This variant is shown to be potentially damaging by in silico analysis. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.99
BayesDel_addAF	Pathogenic	0.58	D
BayesDel_noAF	Pathogenic	0.59
Cadd	Pathogenic	31
Dann	Uncertain	1.0
Eigen	Pathogenic	0.91
Eigen_PC	Pathogenic	0.85
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.93	D;D;D;.;D;D
M_CAP	Pathogenic	0.93	D
MetaRNN	Pathogenic	0.99	D;D;D;D;D;D
MetaSVM	Pathogenic	1.1	D
MutationTaster	Benign	1.0	D;D;D;D
PrimateAI	Pathogenic	0.85	D
Sift4G	Uncertain	0.0020	D;D;D;D;D;D
Polyphen		1.0	D;.;D;D;D;D
Vest4		0.85
MutPred		0.89		.;.;Gain of disorder (P = 0.0079);.;.;.;
MVP		0.99
MPC		2.8
ClinPred		1.0	D
GERP RS		5.5
Varity_R		0.99
gMVP		1.0

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: rs193922268; hg19: chr7-44185192;