rs1554335132
Variant summary
Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PM1PM2PM5PP3_StrongPP5_Very_Strong
The NM_000162.5(GCK):c.776C>T(p.Ala259Val) variant causes a missense change. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic 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. A259S) has been classified as Likely pathogenic.
Frequency
Genomes: not found (cov: 33)
Consequence
GCK
NM_000162.5 missense
NM_000162.5 missense
Scores
9
4
1
Clinical Significance
Conservation
PhyloP100: 6.79
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]
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ACMG classification
Classification made for transcript
Verdict is Pathogenic. Variant got 18 ACMG points.
PM1
?
In a hotspot region, there are 14 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 7 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 chr7-44147738-C-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 2578354.Status of the report is reviewed_by_expert_panel, 3 stars.
PP3
?
MetaRNN computational evidence supports a deleterious effect, 0.989
PP5
?
Variant 7-44147737-G-A is Pathogenic according to our data. Variant chr7-44147737-G-A is described in ClinVar as [Pathogenic]. Clinvar id is 447417.Status of the report is reviewed_by_expert_panel, 3 stars.
Transcripts
RefSeq
Gene | Transcript | HGVSc | HGVSp | Effect | #exon/exons | MANE | UniProt |
---|---|---|---|---|---|---|---|
GCK | NM_000162.5 | c.776C>T | p.Ala259Val | missense_variant | 7/10 | ENST00000403799.8 | |
LOC105375258 | XR_927223.3 | n.87G>A | non_coding_transcript_exon_variant | 1/3 |
Ensembl
Gene | Transcript | HGVSc | HGVSp | Effect | #exon/exons | TSL | MANE | Appris | UniProt |
---|---|---|---|---|---|---|---|---|---|
GCK | ENST00000403799.8 | c.776C>T | p.Ala259Val | missense_variant | 7/10 | 1 | NM_000162.5 | P1 |
Frequencies
GnomAD3 genomes ? Cov.: 33
GnomAD3 genomes
?
Cov.:
33
GnomAD4 exome Cov.: 32
GnomAD4 exome
Cov.:
32
GnomAD4 genome ? Cov.: 33
GnomAD4 genome
?
Cov.:
33
ClinVar
Significance: Pathogenic
Submissions summary: Pathogenic:3Uncertain:1
Revision: reviewed by expert panel
LINK: link
Submissions by phenotype
Maturity onset diabetes mellitus in young Pathogenic:2
Likely risk allele, 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 . However, there is no sufficient evidence to ascertain the significance of rs1554335132 in MODY, yet. - |
Likely pathogenic, criteria provided, single submitter | clinical testing | Ambry Genetics | Mar 17, 2021 | The p.A259V variant (also known as c.776C>T), located in coding exon 7 of the GCK gene, results from a C to T substitution at nucleotide position 776. The alanine at codon 259 is replaced by valine, an amino acid with similar properties. This alteration has been reported in multiple individuals with a clinical and family history consistent with GCK-MODY (Tracz A et al. Exp Clin Endocrinol Diabetes, 2014 Oct;122:503-9; Borowiec M et al. Clin Genet, 2012 Dec;82:587-90). In addition, another alteration at the same codon, p.A259T (c.775G>A), has been described in multiple individuals meeting MODY diagnostic criteria (Capuano M et al. PLoS One, 2012 Jun;7:e38906; Delvecchio M et al. Diabetes Care, 2014 Dec;37:e258-60; Yorifuji T et al. Pediatr Diabetes, 2018 11;19:1164-1172); in one report, p.A259T was confirmed de novo in an individual with impaired glucose tolerance diagnosed in childhood, C-peptide secretion/detectable insulin in absence of insulin treatment, who was also negative for autoantibodies (Glotov OS et al. Mol Med Rep, 2019 Dec;20:4905-4914). Based on internal structural analysis, this variant is anticipated to result in a decrease in structural stability (Cheruvallath ZS et al. Bioorg Med Chem Lett, 2017 06;27:2678-2682). This amino acid position is well conserved in available vertebrate species. In addition, this alteration is predicted to be deleterious by in silico analysis. Based on the majority of available evidence to date, this variant is likely to be pathogenic. - |
Monogenic diabetes Pathogenic:1
Pathogenic, reviewed by expert panel | curation | ClinGen Monogenic Diabetes Variant Curation Expert Panel | Aug 12, 2023 | The c.776C>T variant in the glucokinase gene, GCK, causes an amino acid change of alanine to valine at codon 259 (p.(Ala259Val)) 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). Additionally, this variant was identified in 15 unrelated individuals with hyperglycemia (PS4; PMID:22035297, internal lab contributors). This variant segregated with diabetes/hyperglycemia, with 16 informative meioses in 5 families (PP1_Strong; PMID: 22035297, internal lab contributors). 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.775G>A, p.Ala259Thr has been interpreted as pathogenic by the ClinGen MDEP, and p.Ala259Val has a greater Grantham distance (PM5). Lastly, this variant was identified in two individuals with a clinical history highly specific for GCK-hyperglycemia (FBG 5.5-8 mmol/L and HbA1c 5.6 - 7.6% and OGTT increment < 3 mmol/L) (PP4_Moderate; internal lab contributors). In summary, c. 776C>T 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, PM2_Supporting, PS4, PP1_Strong, PP2, PM5, PP4_Moderate. - |
not specified Uncertain:1
Uncertain significance, criteria provided, single submitter | clinical testing | Athena Diagnostics | Mar 03, 2017 | - - |
Computational scores
Source:
Name
Calibrated prediction
Score
Prediction
AlphaMissense
Pathogenic
BayesDel_addAF
Pathogenic
D
BayesDel_noAF
Pathogenic
Cadd
Uncertain
Dann
Pathogenic
Eigen
Uncertain
Eigen_PC
Uncertain
FATHMM_MKL
Pathogenic
D
LIST_S2
Uncertain
D;D;.;D;D
M_CAP
Pathogenic
D
MetaRNN
Pathogenic
D;D;D;D;D
MetaSVM
Pathogenic
D
MutationTaster
Benign
D;D;D;D
PrimateAI
Uncertain
T
Sift4G
Pathogenic
D;D;D;D;D
Polyphen
P;P;P;D;.
Vest4
MutPred
0.93
.;Loss of disorder (P = 0.1246);.;.;.;
MVP
MPC
1.7
ClinPred
D
GERP RS
Varity_R
gMVP
Splicing
Name
Calibrated prediction
Score
Prediction
SpliceAI score (max)
Details are displayed if max score is > 0.2
Find out detailed SpliceAI scores and Pangolin per-transcript scores at