rs863225345

chr5-112839378-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.3785dup(p.Tyr1262Ter) variant causes a stop gained, 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 (★★). Synonymous variant affecting the same amino acid position (i.e. Y1262Y) has been classified as Likely benign.

• Frequency: Genomes: not found (cov: 32)
• Consequence: APC NM_000038.6 stop_gained, frameshift
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:5
• Conservation: PhyloP100: 8.95

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 522 pathogenic variants in the truncated region.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 5-112839378-T-TA is Pathogenic according to our data. Variant chr5-112839378-T-TA is described in ClinVar as [Likely_pathogenic]. Clinvar id is 217970.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.3785dup	p.Tyr1262Ter	stop_gained, frameshift_variant	16/16	ENST00000257430.9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
APC	ENST00000257430.9	c.3785dup	p.Tyr1262Ter	stop_gained, 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/Likely pathogenic

Submissions summary: Pathogenic:5

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Familial adenomatous polyposis 1 Pathogenic:3

Pathogenic, criteria provided, single submitter	clinical testing	Myriad Genetics, Inc.	Feb 15, 2023	This variant is considered pathogenic. This variant creates a termination codon and is predicted to result in premature protein truncation. -
Pathogenic, criteria provided, single submitter	clinical testing	Invitae	Sep 25, 2017	For these reasons, this variant has been classified as Pathogenic. Different variants (c.3786T>A and c.3785dupA) giving rise to the same protein effect observed here (p.Tyr1262*) have been reported as pathogenic in individuals affected with familial adenomatous polyposis (PMID: 11247896, Invitae). In addition, a different truncation downstream of this variant (p.Ser1276*) has been determined to be pathogenic (PMID: 9452101, 10094547, 15108286, Invitae). This suggests that deletion of this region of the APC protein is causative of disease. While this variant has not been reported in the literature in APC-related diseases, loss-of-function variants in APC are known to be pathogenic (PMID: 17963004, 20685668). This variant is not present in population databases (ExAC no frequency). This sequence change results in a premature translational stop signal in the APC gene (p.Tyr1262*). While this is not anticipated to result in nonsense mediated decay, it is expected to delete the last 1582 amino acids of the APC protein. -
Likely pathogenic, criteria provided, single submitter	clinical testing	Counsyl	May 20, 2016	- -

not provided Pathogenic:1

Likely pathogenic, no assertion criteria provided

research

Mayo Clinic Laboratories, Mayo Clinic

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Hereditary cancer-predisposing syndrome Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Ambry Genetics

Apr 19, 2018

The c.3785dupA pathogenic mutation, located in coding exon 15 of the APC gene, results from a duplication of A at nucleotide position 3785, causing a translational frameshift with a predicted alternate stop codon (p.Y1262*). 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. -

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: rs863225345; hg19: chr5-112175075;