22-28734402-C-T

Position:

• chr22-28734402-C-T

Variant summary

Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PVS1 PM2 PP5_Very_Strong

The NM_007194.4(CHEK2):​c.319+1G>A variant causes a splice donor change. The variant allele was found at a frequency of 0.00000205 in 1,461,524 control chromosomes in the GnomAD database, with no homozygous occurrence. 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 Likely pathogenic (★★).

• Frequency:
  • Genomes: not found (cov: 31)
  • Exomes 𝑓: 0.0000021 (0 hom.)
• Consequence: CHEK2 NM_007194.4 splice_donor
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:8
• Conservation: PhyloP100: 5.01

Genes affected

CHEK2 (HGNC:16627): (checkpoint kinase 2) In response to DNA damage and replication blocks, cell cycle progression is halted through the control of critical cell cycle regulators. The protein encoded by this gene is a cell cycle checkpoint regulator and putative tumor suppressor. It contains a forkhead-associated protein interaction domain essential for activation in response to DNA damage and is rapidly phosphorylated in response to replication blocks and DNA damage. When activated, the encoded protein is known to inhibit CDC25C phosphatase, preventing entry into mitosis, and has been shown to stabilize the tumor suppressor protein p53, leading to cell cycle arrest in G1. In addition, this protein interacts with and phosphorylates BRCA1, allowing BRCA1 to restore survival after DNA damage. Mutations in this gene have been linked with Li-Fraumeni syndrome, a highly penetrant familial cancer phenotype usually associated with inherited mutations in TP53. Also, mutations in this gene are thought to confer a predisposition to sarcomas, breast cancer, and brain tumors. This nuclear protein is a member of the CDS1 subfamily of serine/threonine protein kinases. Several transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Apr 2012]

ACMG classification

Verdict is Pathogenic. Variant got 18 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, LoF is a know mechanism of disease, No cryptic splice site detected. Exon removal results in frameshift change.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 22-28734402-C-T is Pathogenic according to our data. Variant chr22-28734402-C-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 481726.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
CHEK2	NM_007194.4	c.319+1G>A		splice_donor_variant		ENST00000404276.6	NP_009125.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
CHEK2	ENST00000404276.6	c.319+1G>A		splice_donor_variant		1	NM_007194.4	ENSP00000385747	P2

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD3 exomes AF: 0.00000797 AC: 2 AN: 250812 Hom.: 0 AF XY: 0.0000147 AC XY: 2 AN XY: 135656

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.0000327

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00000883

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000205 AC: 3 AN: 1461524 Hom.: 0 Cov.: 33 AF XY: 0.00000413 AC XY: 3 AN XY: 727074

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: 0.0000166

GnomAD4 genome Cov.: 31

Alfa AF: 0.0000434 Hom.: 0

Bravo AF: 0.00000378

ExAC AF: 0.0000247 AC: 3

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:8

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Familial cancer of breast Pathogenic:4

Likely pathogenic, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Sep 15, 2023	In summary, the currently available evidence indicates that the variant is pathogenic, but additional data are needed to prove that conclusively. Therefore, this variant has been classified as Likely Pathogenic. Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. ClinVar contains an entry for this variant (Variation ID: 481726). This variant has not been reported in the literature in individuals affected with CHEK2-related conditions. The frequency data for this variant in the population databases is considered unreliable, as metrics indicate poor data quality at this position in the gnomAD database. This sequence change affects a donor splice site in intron 2 of the CHEK2 gene. It is expected to disrupt RNA splicing. Variants that disrupt the donor or acceptor splice site typically lead to a loss of protein function (PMID: 16199547), and loss-of-function variants in CHEK2 are known to be pathogenic (PMID: 21876083, 24713400). -
Likely pathogenic, criteria provided, single submitter	clinical testing	Baylor Genetics	Nov 17, 2023	- -
Likely pathogenic, criteria provided, single submitter	clinical testing	Myriad Genetics, Inc.	Jun 23, 2023	This variant is considered likely pathogenic. This variant occurs within a consensus splice junction and is predicted to result in abnormal mRNA splicing of either an out-of-frame exon or an in-frame exon necessary for protein stability and/or normal function. -
Pathogenic, criteria provided, single submitter	clinical testing	Department of Molecular Diagnostics, Institute of Oncology Ljubljana	Apr 02, 2020	- -

Hereditary cancer-predisposing syndrome Pathogenic:2

Likely pathogenic, criteria provided, single submitter	clinical testing	Ambry Genetics	Jan 08, 2024	The c.319+1G>A intronic variant results from a G to A substitution one nucleotide after coding exon 1 of the CHEK2 gene. This nucleotide position is highly conserved in available vertebrate species. In silico splice site analysis predicts that this alteration will weaken the native splice donor site. This variant is considered to be rare based on population cohorts in the Genome Aggregation Database (gnomAD). Alterations that disrupt the canonical splice site are expected to cause aberrant splicing, resulting in an abnormal protein or a transcript that is subject to nonsense-mediated mRNA decay. As such, this alteration is classified as likely pathogenic. -
Likely pathogenic, criteria provided, single submitter	clinical testing	Color Diagnostics, LLC DBA Color Health	Mar 16, 2020	This variant causes a G to A nucleotide substitution at the +1 position of intron 2 of the CHEK2 gene. Splice site prediction tools predict that this variant may have a significant impact on RNA splicing. Although RNA studies have not been reported for this variant, this variant is expected to result in an absent or non-functional protein product. This variant has not been reported in individuals affected with hereditary cancer in the literature. This variant has been identified in 2/250812 chromosomes in the general population by the Genome Aggregation Database (gnomAD). Loss of CHEK2 function is a known mechanism of disease (clinicalgenome.org). Based on the available evidence, this variant is classified as Likely Pathogenic. -

Breast cancer, susceptibility to;CN300425:RECLASSIFIED - CDH1 POLYMORPHISM Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Human Genome Sequencing Center Clinical Lab, Baylor College of Medicine

Oct 23, 2019

The c.319+1G>A variant occurs in the donor splice site of intron 2 of the CHEK2 gene and is predicted to affect splicing, likely resulting in disrupted or absent protein product via nonsense mediated decay. While this particular variant has not been reported in individuals with CHEK2-related cancer, a different variant also at the same donor splice site (c.319+2T>A) is associated with thyroid cancer, breast cancer, and colorectal cancer (PMID: 28608266, 26681312, 27696107). The c.319+1G>A variant is very rare in population databases (2/250812 alleles in gnomAD). Loss-of-function variants in CHEK2 are considered pathogenic (PMID: 21876083, 24713400). This variant has been classified as Likely Pathogenic, however due to low allele fraction detected on NGS in this sample, this could represent somatic mosaicism. The clinical significance of this finding warrants further investigation. -

CHEK2-related disorder Pathogenic:1

Likely pathogenic, no assertion criteria provided

clinical testing

PreventionGenetics, part of Exact Sciences

Jul 12, 2024

The CHEK2 c.319+1G>A variant is predicted to disrupt the GT donor site and interfere with normal splicing. To our knowledge, this variant has not been reported in the literature. This variant is reported in 0.0033% of alleles in individuals of South Asian descent in gnomAD and is interpreted as pathogenic/likely pathogenic in ClinVar (https://www.ncbi.nlm.nih.gov/clinvar/variation/481726/). Variants that disrupt the consensus splice donor site in CHEK2 are expected to be pathogenic. This variant is interpreted as likely pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.45	D
BayesDel_noAF	Pathogenic	0.41
CADD	Pathogenic	33
DANN	Uncertain	1.0
Eigen	Pathogenic	1.1
Eigen_PC	Pathogenic	0.96
FATHMM_MKL	Uncertain	0.95	D
MutationTaster	Benign	1.0	D;D;D;D;D;D;D;D;D;D;D
GERP RS		5.3
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		2.8

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.94
SpliceAI score (max)		1.0		Details are displayed if max score is > 0.2
DS_DL_spliceai		1.0		Position offset: 1

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

Publications

LitVar

Other links and lift over

dbSNP: rs765080766; hg19: chr22-29130390;