5-112837562-AAGAG-AAG

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.1974_1975del(p.Asn659GlnfsTer14) 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. R657R) has been classified as Likely benign.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
  • Failed GnomAD Quality Control
• Consequence: APC NM_000038.6 frameshift
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:3
• Conservation: PhyloP100: 9.60

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 1035 pathogenic variants in the truncated region.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 5-112837562-AAG-A is Pathogenic according to our data. Variant chr5-112837562-AAG-A is described in ClinVar as [Pathogenic]. Clinvar id is 433630.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr5-112837562-AAG-A is described in Lovd as [Pathogenic]. Variant chr5-112837562-AAG-A is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
APC	NM_000038.6	c.1974_1975del	p.Asn659GlnfsTer14	frameshift_variant	16/16	ENST00000257430.9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
APC	ENST00000257430.9	c.1974_1975del	p.Asn659GlnfsTer14	frameshift_variant	16/16	5	NM_000038.6	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Data not reliable, filtered out with message: AS_VQSR AF: 6.85e-7 AC: 1 AN: 1460174 Hom.: 0 AF XY: 0.00000138 AC XY: 1 AN XY: 726210

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 9.00e-7

Gnomad4 OTH exome AF: 0.00

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:3

Pathogenic, criteria provided, single submitter	clinical testing	Myriad Genetics, Inc.	May 03, 2023	This variant is considered pathogenic. This variant creates a frameshift predicted to result in premature protein truncation. -
Pathogenic, no assertion criteria provided	clinical testing	Department of Pathology and Laboratory Medicine, Sinai Health System	-	The APC p.Asn659GlnfsX14 variant was identified in 1 of 242 proband chromosomes (frequency: 0.008) from individuals or families with familial adenomatous polyposis, and was not identified in 120 control chromosomes from healthy individuals (Giarola 1999, Kohoutova 2002). The p.Asn659GlnfsX14 variant was also identified in HGMD, “InSiGHT Colon Cancer Database”. The p.Asn659GlnfsX14 deletion variant is predicted to cause a frameshift, which alters the protein's amino acid sequence beginning at codon 659 and leads to a premature stop codon at position 672. This alteration is then predicted to result in a truncated or absent protein and loss of function. 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. -
Pathogenic, criteria provided, single submitter	clinical testing	Invitae	May 22, 2018	This sequence change results in a premature translational stop signal in the APC gene (p.Asn659Glnfs*14). While this is not anticipated to result in nonsense mediated decay, it is expected to disrupt the last 2185 amino acids of the APC protein. For these reasons, this variant has been classified as Pathogenic. Different truncations (p.Ser932*, p.Ala1050Glufs*6, and p.Gln1062*) that lie downstream of this variant have been determined to be pathogenic (PMID: 20685668, 23460355, 15771908). This suggests that deletion of this region of the APC protein is causative of disease. This variant has been observed in two individuals affected with familial adenomatous polyposis (PMID: 10094547, 20685668). This variant is also known as c.1968_1969del in the literature. ClinVar contains an entry for this variant (Variation ID: 433630). This variant is not present in population databases (ExAC no frequency). -

Computational scores

Source: dbNSFP v4.3

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		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: rs863225322; hg19: chr5-112173259;