22-28725091-T-G

Position:

• chr22-28725091-T-G

Variant summary

Our verdict is Uncertain significance. Variant got 4 ACMG points: 6P and 2B. PM1 PM2 PM5 BP4_Moderate

The NM_007194.4(CHEK2):​c.478A>C​(p.Ile160Leu) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,820 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 14/21 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. I160K?) has been classified as Pathogenic.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: CHEK2 NM_007194.4 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:3
• Conservation: PhyloP100: 2.37

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 Uncertain_significance. Variant got 4 ACMG points.

• PM1: In a strand (size 8) in uniprot entity CHK2_HUMAN there are 4 pathogenic changes around while only 0 benign (100%) in NM_007194.4
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr22-28725089-TA-TTT is described in Lovd as [Pathogenic].
• BP4: Computational evidence support a benign effect (MetaRNN=0.18195301).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
CHEK2	NM_007194.4	c.478A>C	p.Ile160Leu	missense_variant	4/15	ENST00000404276.6	NP_009125.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
CHEK2	ENST00000404276.6	c.478A>C	p.Ile160Leu	missense_variant	4/15	1	NM_007194.4	ENSP00000385747	P2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461820 Hom.: 0 Cov.: 32 AF XY: 0.00000138 AC XY: 1 AN XY: 727212

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: 8.99e-7

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Hereditary cancer-predisposing syndrome Uncertain:2

Uncertain significance, criteria provided, single submitter	clinical testing	Ambry Genetics	Feb 10, 2022	The p.I160L variant (also known as c.478A>C), located in coding exon 3 of the CHEK2 gene, results from an A to C substitution at nucleotide position 478. The isoleucine at codon 160 is replaced by leucine, an amino acid with highly similar properties. This amino acid position is not well conserved in available vertebrate species. In addition, this alteration is predicted to be tolerated by in silico analysis. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear. -
Uncertain significance, criteria provided, single submitter	clinical testing	Color Diagnostics, LLC DBA Color Health	Apr 03, 2023	This missense variant replaces isoleucine with leucine at codon 160 of the CHEK2 protein. Computational prediction suggests that this variant may not impact protein structure and function (internally defined REVEL score threshold <= 0.5, PMID: 27666373). To our knowledge, functional studies have not been reported for this variant. This variant has not been reported in individuals affected with CHEK2-related disorders in the literature. This variant has not been identified in the general population by the Genome Aggregation Database (gnomAD). The available evidence is insufficient to determine the role of this variant in disease conclusively. Therefore, this variant is classified as a Variant of Uncertain Significance. -

Familial cancer of breast Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Oct 30, 2023

This sequence change replaces isoleucine, which is neutral and non-polar, with leucine, which is neutral and non-polar, at codon 160 of the CHEK2 protein (p.Ile160Leu). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with CHEK2-related conditions. ClinVar contains an entry for this variant (Variation ID: 481709). Algorithms developed to predict the effect of missense changes on protein structure and function output the following: SIFT: "Not Available"; PolyPhen-2: "Benign"; Align-GVGD: "Not Available". The leucine amino acid residue is found in multiple mammalian species, which suggests that this missense change does not adversely affect 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. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.15
BayesDel_addAF	Uncertain	0.037	T
BayesDel_noAF	Benign	-0.18
CADD	Benign	17
DANN	Benign	0.96
DEOGEN2	Benign	0.23	T;.;T;T;.;T;.;.;T;.;.
Eigen	Benign	-0.42
Eigen_PC	Benign	-0.22
FATHMM_MKL	Uncertain	0.91	D
LIST_S2	Benign	0.76	.;T;.;.;T;T;.;T;T;T;T
M_CAP	Benign	0.030	D
MetaRNN	Benign	0.18	T;T;T;T;T;T;T;T;T;T;T
MetaSVM	Benign	-0.58	T
MutationAssessor	Benign	0.69	N;N;N;N;.;N;N;.;.;.;.
MutationTaster	Benign	1.0	D;D;D;D;D;D;D;D;D;D;D
PrimateAI	Uncertain	0.63	T
PROVEAN	Benign	-0.49	N;N;N;N;N;.;N;N;.;.;.
REVEL	Benign	0.26
Sift	Benign	0.52	T;T;T;T;T;.;T;T;.;.;.
Sift4G	Benign	0.51	T;T;T;T;T;.;T;T;T;.;.
Polyphen		0.017	B;B;B;B;B;B;B;.;.;.;.
Vest4		0.52
MutPred		0.51		Gain of catalytic residue at I160 (P = 0.0925);Gain of catalytic residue at I160 (P = 0.0925);Gain of catalytic residue at I160 (P = 0.0925);Gain of catalytic residue at I160 (P = 0.0925);.;Gain of catalytic residue at I160 (P = 0.0925);Gain of catalytic residue at I160 (P = 0.0925);.;Gain of catalytic residue at I160 (P = 0.0925);Gain of catalytic residue at I160 (P = 0.0925);Gain of catalytic residue at I160 (P = 0.0925);
MVP		0.79
MPC		0.022
ClinPred		0.35	T
GERP RS		3.7
Varity_R		0.39
gMVP		0.52

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: rs876659950; hg19: chr22-29121079;