5-112839187-CAA-CAAA

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.3596dup(p.Ser1200GlufsTer8) 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 Pathogenic (★★). Synonymous variant affecting the same amino acid position (i.e. S1198S) has been classified as Likely benign.

• Frequency: Genomes: not found (cov: 32)
• Consequence: APC NM_000038.6 frameshift
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:3
• Conservation: PhyloP100: 0.436

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 571 pathogenic variants in the truncated region.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 5-112839187-C-CA is Pathogenic according to our data. Variant chr5-112839187-C-CA is described in ClinVar as [Pathogenic]. Clinvar id is 482355.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.3596dup	p.Ser1200GlufsTer8	frameshift_variant	16/16	ENST00000257430.9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
APC	ENST00000257430.9	c.3596dup	p.Ser1200GlufsTer8	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:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Familial adenomatous polyposis 1 Pathogenic:2

Pathogenic, criteria provided, single submitter	clinical testing	Myriad Genetics, Inc.	May 09, 2023	This variant is considered pathogenic. This variant creates a frameshift predicted to result in premature protein truncation. -
Pathogenic, criteria provided, single submitter	clinical testing	Invitae	Apr 29, 2022	This sequence change creates a premature translational stop signal (p.Ser1200Glufs*8) in the APC gene. While this is not anticipated to result in nonsense mediated decay, it is expected to disrupt the last 1644 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: 12173026, 17963004). This variant is also known as 3614insA. ClinVar contains an entry for this variant (Variation ID: 482355). 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. This variant disrupts a region of the APC protein in which other variant(s) (p.Tyr2645Lysfs*14) have been determined to be pathogenic (PMID: 8381579, 9824584, 22135120, 27081525). This suggests that this is a clinically significant region of the protein, and that variants that disrupt it are likely to be disease-causing. 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

Jun 06, 2017

The c.3596dupA pathogenic mutation, located in coding exon 15 of the APC gene, results from a duplication of A at nucleotide position 3596, causing a translational frameshift with a predicted alternate stop codon (p.S1200Efs*8). This mutation has been previously reported (designated as 3614insA) in an individual with a clinical diagnosis of familial adenomatous polyposis (FAP) presenting with a severe phenotype with more than 5000 polyps (Michils G et al. Eur. J. Hum. Genet. 2002 Sep; 10(9):505-10). It has also been detected in 1/24 Chilean families with FAP (De la Fuente MK et al. Dis. Colon Rectum, 2007 Dec;50:2142-8). 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. -

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: rs864622106; hg19: chr5-112174884;