rs876658724

chr5-112838660-T-TA

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.3067dup(p.Thr1023AsnfsTer6) variant causes a frameshift change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. Variant has been reported in ClinVar as Pathogenic (★★).

• Frequency: Genomes: not found (cov: 32)
• Consequence: APC NM_000038.6 frameshift
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:2 U:1
• Conservation: PhyloP100: 8.72

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 does not undergo nonsense mediated mRNA decay. Variant is located in the 3'-most exon, not predicted to undergo nonsense mediated mRNA decay. There are 749 pathogenic variants in the truncated region.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 5-112838660-T-TA is Pathogenic according to our data. Variant chr5-112838660-T-TA is described in ClinVar as [Pathogenic]. Clinvar id is 230713.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
APC	NM_000038.6	c.3067dup	p.Thr1023AsnfsTer6	frameshift_variant	16/16	ENST00000257430.9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
APC	ENST00000257430.9	c.3067dup	p.Thr1023AsnfsTer6	frameshift_variant	16/16	5	NM_000038.6	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 33

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:2 Uncertain:1

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Familial adenomatous polyposis 1 Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Invitae

Jan 07, 2024

This sequence change creates a premature translational stop signal (p.Thr1023Asnfs*6) in the APC gene. While this is not anticipated to result in nonsense mediated decay, it is expected to disrupt the last 1821 amino acid(s) of the APC protein. This variant is not present in population databases (gnomAD no frequency). This premature translational stop signal has been observed in individual(s) with familial adenomatous polyposis (PMID: 11741105, 17604324, 20685668, 23159591). ClinVar contains an entry for this variant (Variation ID: 230713). This variant is expected to disrupt the EB1 and HDLG binding sites, which mediate interactions with the cytoskeleton (PMID: 15311282, 17293347). While functional studies have not been performed to directly test the effect on APC protein function, this suggests that disruption of the C-terminal portion of the protein is functionally important. A different truncation (p.Tyr2645Lysfs*14) that lies downstream of this variant has been determined to be pathogenic (PMID: 9824584, 1316610, 27081525, 8381579, 22135120, Invitae). This suggests that deletion of this region of the APC protein is causative of disease. For these reasons, this variant has been classified as Pathogenic. -

Hereditary cancer-predisposing syndrome Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Ambry Genetics

Oct 31, 2023

The c.3067dupA pathogenic mutation, located in coding exon 15 of the APC gene, results from a duplication of A at nucleotide position 3067, causing a translational frameshift with a predicted alternate stop codon (p.T1023Nfs*6). This alteration has been previously identified in a family with classic familial adenomatous polyposis (FAP) with manifestations including >100 adenomatous polyps, hepatoblastoma and congenital hypertrophy of the retinal pigment epithelium (CHRPE) (Kerr SE et al, J Mol Diagn 2013 Jan; 15(1):31-43). It has also been described as a mosaic finding, occurring in 15% of lymphocytes in an individual with 35 polyps and no colon cancer (Hes FJ et al, Gut 2008 Jan; 57(1):71-6). In addition to the clinical data presented in the literature, this alteration is expected to result in loss of function by premature protein truncation. As such, this alteration is interpreted as a disease-causing mutation. -

Carcinoma of colon Uncertain:1

Uncertain significance, no assertion criteria provided

clinical testing

Department of Pathology and Laboratory Medicine, Sinai Health System

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Computational scores

Source: dbNSFP v4.3

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: rs876658724; hg19: chr5-112174357;