chr5-112841420-C-CAA

Position:

• chr5-112841420-C-CAA

Variant summary

Our verdict is Likely pathogenic. Variant got 8 ACMG points: 8P and 0B. PVS1_Strong PM2 PP5_Moderate

The NM_000038.6(APC):​c.5827_5828insAA​(p.Arg1943LysfsTer28) 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 (★).

• Frequency: Genomes: not found (cov: 32)
• Consequence: APC NM_000038.6 frameshift
• Clinical Significance: Pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 2.77

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 Likely_pathogenic. Variant got 8 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 9 pathogenic variants in the truncated region.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 5-112841420-C-CAA is Pathogenic according to our data. Variant chr5-112841420-C-CAA is described in ClinVar as [Pathogenic]. Clinvar id is 470023.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
APC	NM_000038.6	c.5827_5828insAA	p.Arg1943LysfsTer28	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.5827_5828insAA	p.Arg1943LysfsTer28	frameshift_variant	16/16	5	NM_000038.6	ENSP00000257430	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 65

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

Familial adenomatous polyposis 1 Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Apr 15, 2017

A different truncation downstream of this variant (p.Asn1979Thrfs*64) has been determined to be pathogenic (PMID: 20434453, 9824584, 26681312). 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. Loss-of-function variants in APC are known to be pathogenic (PMID: 20685668, 17963004). This particular variant has been reported in the literature in an individual affected with familial adenomatous polyposis (PMID: 21779980). This sequence change inserts 2 nucleotides in exon 16 of the APC mRNA (c.5827_5828insAA), causing a frameshift at codon 1943. This creates a premature translational stop signal in the last exon of the APC mRNA (p.Arg1943Lysfs*28). While this is not anticipated to result in nonsense mediated decay, it is expected to delete the last 873 amino acids of the APC protein, which accounts for 31% of the full length protein. -

Computational scores

Source: dbNSFP v4.3

Splicing

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

LitVar

Other links and lift over

dbSNP: rs1554087023; hg19: chr5-112177117;