chr5-112838393-CACTT-C

Variant names:

• chr5-112838393-CACTT-C
• rs1131691143
• NM_000038.6:c.2802_2805delTTAC

Variant summary

Our verdict is Pathogenic. The variant received 18 ACMG points: 18P and 0B. PVS1 PM2 PP5_Very_Strong

The NM_000038.6(APC):​c.2802_2805delTTAC​(p.Tyr935IlefsTer19) variant causes a frameshift change. The variant allele was found at a frequency of 0.000000684 in 1,461,856 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Pathogenic (★★). Synonymous variant affecting the same amino acid position (i.e. T934T) has been classified as Likely benign.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: APC NM_000038.6 frameshift
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:6
• Conservation: PhyloP100: 3.96
• Publications: 12 publications found

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]

APC Gene-Disease associations (from GenCC):

• classic or attenuated familial adenomatous polyposis

  Inheritance: AD Classification: DEFINITIVE Submitted by: ClinGen
• desmoid tumor

  Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: G2P, Genomics England PanelApp
• familial adenomatous polyposis 1

  Inheritance: AD Classification: DEFINITIVE, STRONG, MODERATE Submitted by: Genomics England PanelApp, Labcorp Genetics (formerly Invitae), Ambry Genetics
• gastric adenocarcinoma and proximal polyposis of the stomach

  Inheritance: AD Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Ambry Genetics, Labcorp Genetics (formerly Invitae), ClinGen, Orphanet
• sarcoma

  Inheritance: AD Classification: MODERATE Submitted by: Genomics England PanelApp
• APC-related attenuated familial adenomatous polyposis

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• Turcot syndrome with polyposis

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• Cenani-Lenz syndactyly syndrome

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet

ENSG00000258864 (HGNC:):

ACMG classification

Our verdict: Pathogenic. The variant received 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 1306 pathogenic variants in the truncated region.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 5-112838393-CACTT-C is Pathogenic according to our data. Variant chr5-112838393-CACTT-C is described in ClinVar as Pathogenic. ClinVar VariationId is 429056.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.2802_2805delTTAC	p.Tyr935IlefsTer19	frameshift_variant	Exon 16 of 16	ENST00000257430.9	NP_000029.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
APC	ENST00000257430.9	c.2802_2805delTTAC	p.Tyr935IlefsTer19	frameshift_variant	Exon 16 of 16	5	NM_000038.6	ENSP00000257430.4
ENSG00000258864	ENST00000520401.1	n.228+9424_228+9427delTTAC		intron_variant	Intron 3 of 7	3		ENSP00000454861.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461856 Hom.: 0 AF XY: 0.00000138 AC XY: 1 AN XY: 727228

⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.

African (AFR) AF: 0.00 AC: 0 AN: 33480

American (AMR) AF: 0.00 AC: 0 AN: 44720

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26136

East Asian (EAS) AF: 0.00 AC: 0 AN: 39694

South Asian (SAS) AF: 0.00 AC: 0 AN: 86258

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53402

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5768

European-Non Finnish (NFE) AF: 8.99e-7 AC: 1 AN: 1112004

Other (OTH) AF: 0.00 AC: 0 AN: 60394

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0), which strongly suggests a high chance of mosaicism in these individuals.

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:6

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Familial adenomatous polyposis 1 Pathogenic:2

Oct 28, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change creates a premature translational stop signal (p.Tyr935Ilefs*19) in the APC gene. While this is not anticipated to result in nonsense mediated decay, it is expected to disrupt the last 1909 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 (FAP) (PMID: 9375853, 14961559, 17411426, 21779980). This variant is also known as 2800 Del4 and c.2800_2803delACTT. ClinVar contains an entry for this variant (Variation ID: 429056). 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. -

May 05, 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. -

Hereditary cancer-predisposing syndrome Pathogenic:2

Jan 07, 2025

Ambry Genetics

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The c.2802_2805delTTAC pathogenic mutation, located in coding exon 15 of the APC gene, results from a deletion of 4 nucleotides at nucleotide positions 2802 to 2805, causing a translational frameshift with a predicted alternate stop codon (p.Y935Ifs*19). This alteration occurs at the 3' terminus of theAPC gene, is not expected to trigger nonsense-mediated mRNA decay, and impacts the last 1909 amino acids of the protein. However, premature stop codons are typically deleterious in nature and the impacted region is critical for protein function (Ambry internal data). Additionally, this mutation has been reported in multiple unrelated FAP families (Khan N et al. Sci Rep. 2017 May;7:2214; Plawski A, Slomski R. J Appl Genet. 2008;49(4):407-14; Friedl W et al. Hered Cancer Clin Pract. 2005 Sep;3:95-114; Wallis YL et al. J. Med. Genet. 1999 Jan;36:14-20). Based on the supporting evidence, this alteration is interpreted as a disease-causing mutation. -

Feb 17, 2020

Color Diagnostics, LLC DBA Color Health

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant deletes 4 nucleotides in exon 16 of the APC gene, creating a frameshift and premature translation stop signal. This variant is expected to result in an absent or non-functional protein product. To our knowledge, functional studies have not been performed for this variant. This variant has been reported in at least 18 individuals affected with FAP across multiple ethnicities (PMID: 10768871, 14961559, 15108288, 15951963, 17411426, 18433509, 19029688, 20223039, 21779980, 8187091, 9375853, 9950360). This variant has not been identified in the general population by the Genome Aggregation Database (gnomAD). Loss of APC function is a known mechanism of disease (clinicalgenome.org). Based on the available evidence, this variant is 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.Tyr935IlefsX19 variant was identified in 11 of 4890 proband chromosomes (frequency: 0.002) from individuals or families with FAP (Wallis 1999, Friedl 2005, Kanter-Smoler 2008, Plawski 2008, Bisgaard 2004). The variant was also identified in the COSMIC database 3X, and the InSiGHT Colon Cancer Gene Variant Database 19X as pathogenic. The variant was not identified in the Clinvitae database, “Mismatch Repair Genes Variant Database”, “MMR Gene Unclassified Variants Database”, “Zhejiang Colon Cancer Database”, the ClinVar database, GeneInsight COGR database, or UMD. The p.Tyr935IlefsX19 deletion variant is predicted to cause a frameshift, which alters the protein's amino acid sequence beginning at codon 935 and leads to a premature stop codon at position 953. This alteration is then predicted to result in a truncated or absent protein and loss of function. In addition, several studies have reported a mutation in FAP patients 2 bp upstream at c.2800_2803delACTT which leads to a premature stop codon at the same amino acid position, 953 (Miyaki 1994, Enomoto 2000, Armstrong 1997, Stekrova 2007, DeRosa 2003). 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 25, 2016

Quest Diagnostics Nichols Institute San Juan Capistrano

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
PhyloP100		4.0
Mutation Taster		=0/200	disease causing (ClinVar)

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

Other links and lift over

dbSNP: rs1131691143; hg19: chr5-112174090; COSMIC: COSV57332042; COSMIC: COSV57332042;