5-112839037-CTGAA-C

Position:

• chr5-112839037-CTGAA-C

Variant summary

Our verdict is Pathogenic. Variant got 12 ACMG points: 12P and 0B. PVS1 PM2 PP5_Moderate

The NM_000038.6(APC):​c.3444_3447del​(p.Glu1149LysfsTer15) 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 Pathogenic (★). Synonymous variant affecting the same amino acid position (i.e. S1148S) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 32)
• Consequence: APC NM_000038.6 frameshift
• Clinical Significance: Pathogenic criteria provided, single submitter P:2
• Conservation: PhyloP100: 7.96

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 12 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 635 pathogenic variants in the truncated region.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 5-112839037-CTGAA-C is Pathogenic according to our data. Variant chr5-112839037-CTGAA-C is described in ClinVar as [Pathogenic]. Clinvar id is 433644.Status of the report is criteria_provided_single_submitter, 1 stars. Variant chr5-112839037-CTGAA-C is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
APC	NM_000038.6	c.3444_3447del	p.Glu1149LysfsTer15	frameshift_variant	16/16	ENST00000257430.9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
APC	ENST00000257430.9	c.3444_3447del	p.Glu1149LysfsTer15	frameshift_variant	16/16	5	NM_000038.6	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

Submissions summary: Pathogenic:2

Revision: criteria provided, single submitter

Submissions by phenotype

Carcinoma of colon Pathogenic:1

Pathogenic, no assertion criteria provided

clinical testing

Department of Pathology and Laboratory Medicine, Sinai Health System

-

The p.Glu1149LysfsX15 deletion variant has been previously reported in the literature in two individuals with familial adenomatous polyposis (Lagard 2010). This deletion is predicted to cause a frameshift, which alters the protein's amino acid sequence beginning at codon 1149 and leads to a premature stop codon 15 amino acids downstream. This alteration is then predicted to lead to a truncated or absent protein and loss of function. Loss of function of the APC gene is a known disease mechanism and is the type of DNA alteration that is expected to cause FAP. In summary, based on the above information, this variant is classified as pathogenic. -

Familial adenomatous polyposis 1 Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Dec 06, 2018

For these reasons, this variant has been classified as Pathogenic. This variant disrupts the C-terminus of the APC protein. Other variant(s) that disrupt this region (p.Tyr2645Lysfs*14) have been determined to be pathogenic (PMID: 9824584, 1316610, 27081525, 8381579, 22135120, Invitae). This suggests that variants that disrupt this region of the protein are likely to be 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. This variant has been observed in individuals with colonic adenomatous polyposis (PMID: 20685668). ClinVar contains an entry for this variant (Variation ID: 433644). 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.Glu1149Lysfs*15). While this is not anticipated to result in nonsense mediated decay, it is expected to disrupt the last 1695 amino acids of the APC protein. -

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: rs1554085005; hg19: chr5-112174734;