7-44145495-A-T

Position:

• chr7-44145495-A-T

Variant summary

Our verdict is Likely pathogenic. Variant got 8 ACMG points: 8P and 0B. PVS1_Strong PM2 PP5_Moderate

The NM_000162.5(GCK):​c.1253+2T>A variant causes a splice donor, intron change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Pathogenic (★).

• Frequency: Genomes: not found (cov: 33)
• Consequence: GCK NM_000162.5 splice_donor, intron
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Pathogenic criteria provided, single submitter P:2
• Conservation: PhyloP100: 9.26

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 (HGNC:):

ACMG classification

Verdict is Likely_pathogenic. Variant got 8 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, product NOT destroyed by NMD, known LOF gene, truncates exone, which is 0.16666667 fraction of the gene. Cryptic splice site detected, with MaxEntScore 5.8, offset of 25, new splice context is: ctgGTaaag. Cryptic site results in frameshift change. If cryptic site found is not functional and variant results in exon loss, it results in inframe change.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 7-44145495-A-T is Pathogenic according to our data. Variant chr7-44145495-A-T is described in ClinVar as [Pathogenic]. Clinvar id is 393449.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
GCK	NM_000162.5	c.1253+2T>A		splice_donor_variant, intron_variant		ENST00000403799.8	NP_000153.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
GCK	ENST00000403799.8	c.1253+2T>A		splice_donor_variant, intron_variant		1	NM_000162.5	ENSP00000384247.3

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 33

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:2

Revision: criteria provided, single submitter

Submissions by phenotype

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

Pathogenic, criteria provided, single submitter

clinical testing

Translational Genomics Laboratory, University of Maryland School of Medicine

Jun 08, 2017

The c.1253+2T>A variant in the GCK gene removes a splice donor site in IVS9 (19339519). Canonical splice site variants can often be assumed to disrupt gene function by leading to a complete absence of the gene product by lack of transcription or nonsense-mediated decay of an altered transcript. The c.1253+2T>A variant was not observed in the NHLBI Exome Sequencing Project, 1000 Genomes Project, or Exome Aggregation Consortium databases. Splice site mutations in the GCK gene, including ones in IVS9, have been reported previously in patients with a clinical picture consistent with Maturity-Onset Diabetes of the Young, Type 2 (MODY2, also called GCK-MODY) (19790256; 14517946). Additionally, multiple lines of computational evidence (MutationTaster, CADD, GERP) predict this variant is probably damaging to the protein structure or function; ACMG Criteria = PVS1, PM2, PP3 -

Monogenic diabetes Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Translational Genomics Laboratory, University of Maryland School of Medicine

Jun 12, 2015

The c.1253+2T>A variant in the GCK gene removes a splice donor site in IVS9 (19339519). Canonical splice site variants can often be assumed to disrupt gene function by leading to a complete absence of the gene product by lack of transcription or nonsense-mediated decay of an altered transcript. Splice site mutations in the GCK gene have been reported previously in patients with Maturity-Onset Diabetes of the Young, Type 2 (MODY2, also called GCK-MODY) (19790256; 14517946). The c.1253+2T>A variant was not observed in the NHLBI Exome Sequencing Project, 1000 Genomes Project, or Exome Aggregation Consortium databases. Multiple lines of computational evidence (MutationTaster, CADD, GERP) predict this variant is probably damaging to the protein structure or function; ACMG Criteria = PVS1, PM2, PP3 -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Pathogenic	0.30
CADD	Pathogenic	36
DANN	Uncertain	0.99
Eigen	Pathogenic	1.2
Eigen_PC	Pathogenic	1.0
FATHMM_MKL	Pathogenic	0.99	D
GERP RS		5.6

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.93
SpliceAI score (max)		1.0		Details are displayed if max score is > 0.2
DS_DG_spliceai		0.84		Position offset: -23
DS_DL_spliceai		1.0		Position offset: 2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

LitVar

Other links and lift over

dbSNP: rs1057524902; hg19: chr7-44185094;