rs193922302

Positions:

• chr7-44150956-C-T

Variant summary

Our verdict is Pathogenic. Variant got 12 ACMG points: 12P and 0B. PS4_Moderate PS3 PP1_Strong PM2_Supporting PP3

This summary comes from the ClinGen Evidence Repository: The c.483G>A variant in the glucokinase gene, GCK, is a synonymous (silent) variant at codon 161 (p.(Lys161=)) of NM_000162.5. This variant is absent from gnomAD v2.1.1 (PM2_Supporting). It is predicted by SpliceAI to impact splicing (SpliceAI score of 0.85 for donor gain and 0.52 for donor loss, which are greater than the MDEP cutoff of 0.2) (PP3), and there is evidence from RNA studies that this variant results in aberrant splicing, indicating that this variant impacts protein function (PS3; Internal lab contributor). This variant was identified in five unrelated individuals with mildly elevated HbA1c that did not require treatment, and segregated with the phenotype, with four informative meioses in three families (PS4_Moderate, PP1_Strong; PMID:1956454, Internal lab contributors). In summary, c.483G>A meets the criteria to be classified as pathogenic for monogenic diabetes. ACMG/AMP criteria applied, as specified by the ClinGen MDEP VCEP (specification version 1.1, approved 3/23/23): PM2_Supporting, PP3, PS4_Moderate, PP1_Strong, PS3. LINK:https://erepo.genome.network/evrepo/ui/classification/CA213792/MONDO:0015967/086

• Frequency: Genomes: not found (cov: 32)
• Consequence: GCK NM_000162.5 splice_region, synonymous
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Pathogenic reviewed by expert panel P:4
• Conservation: PhyloP100: 7.84

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 12 ACMG points.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
GCK	NM_000162.5	c.483G>A	p.Lys161=	splice_region_variant, synonymous_variant	4/10	ENST00000403799.8
GCK	NM_033507.3	c.486G>A	p.Lys162=	splice_region_variant, synonymous_variant	4/10
GCK	NM_033508.3	c.480G>A	p.Lys160=	splice_region_variant, synonymous_variant	5/11
GCK	NM_001354800.1	c.483G>A	p.Lys161=	splice_region_variant, synonymous_variant	4/11

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
GCK	ENST00000403799.8	c.483G>A	p.Lys161=	splice_region_variant, synonymous_variant	4/10	1	NM_000162.5	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:4

Revision: reviewed by expert panel

Submissions by phenotype

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

- -

Maturity onset diabetes mellitus in young Pathogenic:1

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 rs193922302 in MODY, yet. -

Monogenic diabetes Pathogenic:1

Pathogenic, reviewed by expert panel

curation

ClinGen Monogenic Diabetes Variant Curation Expert Panel

May 26, 2023

The c.483G>A variant in the glucokinase gene, GCK, is a synonymous (silent) variant at codon 161 (p.(Lys161=)) of NM_000162.5. This variant is absent from gnomAD v2.1.1 (PM2_Supporting). It is predicted by SpliceAI to impact splicing (SpliceAI score of 0.85 for donor gain and 0.52 for donor loss, which are greater than the MDEP cutoff of 0.2) (PP3), and there is evidence from RNA studies that this variant results in aberrant splicing, indicating that this variant impacts protein function (PS3; Internal lab contributor). This variant was identified in five unrelated individuals with mildly elevated HbA1c that did not require treatment, and segregated with the phenotype, with four informative meioses in three families (PS4_Moderate, PP1_Strong; PMID: 1956454, Internal lab contributors). In summary, c.483G>A meets the criteria to be classified as pathogenic for monogenic diabetes. ACMG/AMP criteria applied, as specified by the ClinGen MDEP VCEP (specification version 1.1, approved 3/23/23): PM2_Supporting, PP3, PS4_Moderate, PP1_Strong, PS3. -

not provided Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Athena Diagnostics

Aug 29, 2023

This variant has been identified in multiple unrelated individuals with clinical features associated with this gene and appears to segregate with disease in at least one family. This variant has not been reported in large, multi-ethnic general populations (http://gnomad.broadinstitute.org). Assessment of experimental evidence suggests this variant results in abnormal protein function. (Personal communication related to ClinVar ID: 36224, Accession: SCV003932645.1) -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.13
CADD	Pathogenic	28
DANN	Benign	0.92

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	1.0
SpliceAI score (max)		0.85		Details are displayed if max score is > 0.2
DS_DG_spliceai		0.85		Position offset: 24
DS_DL_spliceai		0.52		Position offset: 0

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

Publications

LitVar

Other links and lift over

dbSNP: rs193922302; hg19: chr7-44190555;