chr5-112821929-C-CTG

Variant names:

• chr5-112821929-C-CTG
• rs1554080698
• NM_000038.6:c.1354_1355dupGT

Variant summary

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

The NM_000038.6(APC):​c.1354_1355dupGT​(p.Leu453PhefsTer2) variant causes a frameshift change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. Variant has been reported in ClinVar as Likely pathogenic (★★). Variant results in nonsense mediated mRNA decay.

• Frequency: Genomes: not found (cov: 32)
• Consequence: APC NM_000038.6 frameshift
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:6
• Conservation: PhyloP100: 0.0170

Genes affected

APC (HGNC:583): (APC regulator of WNT signaling pathway) This gene encodes a tumor suppressor protein that acts as an antagonist of the Wnt signaling pathway. It is also involved in other processes including cell migration and adhesion, transcriptional activation, and apoptosis. Defects in this gene cause familial adenomatous polyposis (FAP), an autosomal dominant pre-malignant disease that usually progresses to malignancy. Mutations in the APC gene have been found to occur in most colorectal cancers, where disease-associated mutations tend to be clustered in a small region designated the mutation cluster region (MCR) and result in a truncated protein product. [provided by RefSeq, Jun 2022]

ACMG classification

Verdict is Pathogenic. Variant got 18 ACMG points.

• PVS1: Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 5-112821929-C-CTG is Pathogenic according to our data. Variant chr5-112821929-C-CTG is described in ClinVar as [Likely_pathogenic]. Clinvar id is 433619.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
APC	NM_000038.6	c.1354_1355dupGT	p.Leu453PhefsTer2	frameshift_variant	Exon 11 of 16	ENST00000257430.9	NP_000029.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
APC	ENST00000257430.9	c.1354_1355dupGT	p.Leu453PhefsTer2	frameshift_variant	Exon 11 of 16	5	NM_000038.6	ENSP00000257430.4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 30

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:6

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Familial adenomatous polyposis 1 Pathogenic:2

May 01, 2023

Myriad Genetics, Inc.

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant is considered pathogenic. This variant creates a frameshift predicted to result in premature protein truncation. -

Nov 11, 2017

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Loss-of-function variants in APC are known to be pathogenic (PMID: 17963004, 20685668). This variant has not been reported in the literature in individuals with APC-related disease. ClinVar contains an entry for this variant (Variation ID: 433619). This sequence change creates a premature translational stop signal (p.Leu453Phefs*2) in the APC gene. It is expected to result in an absent or disrupted protein product. This variant is not present in population databases (ExAC no frequency). For these reasons, this variant has been classified as Pathogenic. -

Carcinoma of colon Pathogenic:1

-

Department of Pathology and Laboratory Medicine, Sinai Health System

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: clinical testing

The APC p.Leu453PhefsX2 variant was not identified in the literature nor was it identified in the dbSNP, 1000 Genomes Project, NHLBI Exome Sequencing Project (Exome Variant Server), HGMD, COSMIC, MutDB, “Mismatch Repair Genes Variant Database”, “MMR Gene Unclassified Variants Database”, “InSiGHT Colon Cancer Database”, “Zhejiang Colon Cancer Database”, ClinVar database, or UMD databases. The p.Leu453PhefsX2 duplication variant is predicted to cause a frameshift, which alters the protein's amino acid sequence beginning at codon 1354 and leads to a premature stop codon 2 codons downstream. This alteration is then predicted to result in a truncated or absent protein and loss of function. Loss of function variants of the APC gene are an established mechanism of disease in familial adenomatous polyposis and is the type of variant expected to cause the disorder. In summary, based on the above information, this variant meets our laboratory’s criteria to be classified as pathogenic. -

not provided Pathogenic:1

Oct 13, 2022

GeneDx

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Frameshift variant predicted to result in protein truncation or nonsense mediated decay in a gene for which loss of function is a known mechanism of disease; Not observed at significant frequency in large population cohorts (gnomAD); Has not been previously published as pathogenic or benign to our knowledge -

Hereditary cancer-predisposing syndrome Pathogenic:1

Apr 13, 2016

Ambry Genetics

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The c.1354_1355dupGT pathogenic mutation, located in coding exon 10 of the APC gene, results from a duplication of GT at nucleotide position 1354, causing a translational frameshift with a predicted alternate stop codon. Since frameshifts are typically deleterious in nature, this alteration is interpreted as a disease-causing mutation (ACMG Recommendations for Standards for Interpretation and Reporting of Sequence Variations. Revision 2007. Genet Med. 2008;10:294). -

Desmoid disease, hereditary;C2713442:Familial adenomatous polyposis 1 Pathogenic:1

Aug 01, 2014

Department of Pathology and Laboratory Medicine, Sinai Health System

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Computational scores

Source: dbNSFP v4.3

Splicing

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

Publications

LitVar

Other links and lift over

dbSNP: rs1554080698; hg19: chr5-112157626;