5-112839719-CTA-C

Position:

• chr5-112839719-CTA-C

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.4127_4128del​(p.Tyr1376CysfsTer9) 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 Likely pathogenic (★★).

• Frequency: Genomes: not found (cov: 32)
• Consequence: APC NM_000038.6 frameshift
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:5
• Conservation: PhyloP100: 7.67

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 73 pathogenic variants in the truncated region.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 5-112839719-CTA-C is Pathogenic according to our data. Variant chr5-112839719-CTA-C is described in ClinVar as [Likely_pathogenic]. Clinvar id is 548663.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr5-112839719-CTA-C is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
APC	NM_000038.6	c.4127_4128del	p.Tyr1376CysfsTer9	frameshift_variant	16/16	ENST00000257430.9	NP_000029.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
APC	ENST00000257430.9	c.4127_4128del	p.Tyr1376CysfsTer9	frameshift_variant	16/16	5	NM_000038.6	ENSP00000257430	P1

Frequencies

GnomAD3 genomes Cov.: 32

We have no GnomAD4 exomes data on this position. Probably position not covered by the project.

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:5

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Familial adenomatous polyposis 1 Pathogenic:4

Pathogenic, no assertion criteria provided	literature only	Yale Center for Mendelian Genomics, Yale University	Nov 27, 2015	- -
Likely pathogenic, criteria provided, single submitter	clinical testing	MGZ Medical Genetics Center	Sep 07, 2021	- -
Pathogenic, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Jan 01, 2022	For these reasons, this variant has been classified as Pathogenic. 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. 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. ClinVar contains an entry for this variant (Variation ID: 548663). This premature translational stop signal has been observed in individual(s) with clinical features of familial adenomatous polyposis (FAP) (PMID: 20223039). This variant is not present in population databases (gnomAD no frequency). This sequence change creates a premature translational stop signal (p.Tyr1376Cysfs*9) in the APC gene. While this is not anticipated to result in nonsense mediated decay, it is expected to disrupt the last 1468 amino acid(s) of the APC protein. -
Pathogenic, criteria provided, single submitter	clinical testing	Myriad Genetics, Inc.	May 10, 2023	This variant is considered pathogenic. This variant creates a frameshift predicted to result in premature protein truncation. -

Hereditary cancer-predisposing syndrome Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Ambry Genetics

Sep 21, 2020

The c.4127_4128delAT pathogenic mutation, located in coding exon 15 of the APC gene, results from a deletion of two nucleotides at nucleotide positions 4127 to 4128, causing a translational frameshift with a predicted alternate stop codon (p.Y1376Cfs*9). This alteration occurs at the 3' terminus of theAPC gene and is not expected to trigger nonsense-mediated mRNA decay. However, premature stop codons are typically deleterious in nature, the impacted region is critical for protein function, and a significant portion of the protein is affected (Ambry internal data). This pathogenic variant has been reported in several unrelated patients/families with a clinical diagnosis of FAP or AFAP (Friedl W et al. Hered Cancer Clin Pract. 2005 Sep;3:95-114; Aceto G et al. Hum. Mutat. 2005 Oct;26:394; Lagarde A et al. J. Med. Genet. 2010 Oct;47:721-2; Chen QW et al. Asian Pac. J. Cancer Prev. 2015;16:4915-20). This variant was not reported in population-based cohorts in the Genome Aggregation Database (gnomAD). Based on the supporting evidence, this alteration is interpreted as a disease-causing mutation. -

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: rs1554085533; hg19: chr5-112175416;