rs863225310

Positions:

• chr5-112819345-G-A
• chr5-112819345-G-C
• chr5-112819345-G-T

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.1312+1G>A variant causes a splice donor change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Likely pathogenic (★★).

• Frequency: Genomes: not found (cov: 32)
• Consequence: APC NM_000038.6 splice_donor
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:6
• 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: Splicing +-2 bp (donor or acceptor) variant, LoF is a know mechanism of disease, No cryptic splice site detected. Exon removal results in frameshift change.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 5-112819345-G-A is Pathogenic according to our data. Variant chr5-112819345-G-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 217923.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr5-112819345-G-A is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
APC	NM_000038.6	c.1312+1G>A		splice_donor_variant		ENST00000257430.9	NP_000029.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
APC	ENST00000257430.9	c.1312+1G>A		splice_donor_variant		5	NM_000038.6	ENSP00000257430	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 33

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:6

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Familial adenomatous polyposis 1 Pathogenic:3

Likely pathogenic, criteria provided, single submitter	clinical testing	Myriad Genetics, Inc.	May 01, 2023	This variant is considered likely pathogenic. This variant occurs within a consensus splice junction and is predicted to result in abnormal mRNA splicing of either an out-of-frame exon or an in-frame exon necessary for protein stability and/or normal function. -
Pathogenic, criteria provided, single submitter	clinical testing	Baylor Genetics	Nov 23, 2021	- -
Pathogenic, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Jun 12, 2019	For these reasons, this variant has been classified as Pathogenic. Experimental studies have shown that this variant disrupts mRNA splicing (PMID: 26625971). This variant has been observed in individuals with clinical features of familial adenomatous polyposis (PMID: 12007223, 23159591) and observed to segregate with disease in a family (PMID: 26625971). This variant is also known as IVS9+1G>A in the literature. ClinVar contains an entry for this variant (Variation ID: 217923). This variant is not present in population databases (ExAC no frequency). This sequence change affects a donor splice site in intron 10 of the APC gene. It is expected to disrupt RNA splicing and likely results in an absent or disrupted protein product. -

Carcinoma of colon Pathogenic:1

Pathogenic, no assertion criteria provided

clinical testing

Department of Pathology and Laboratory Medicine, Sinai Health System

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The APC c.1312+1G>A variant was identified in 3 of 3324 proband chromosomes (frequency: 0.001) from individuals or families with FAP, and was not identified in 100 control chromosomes from healthy individuals (Gavert 2002, Kerr 2013). The variant was also identified in dbSNP (ID: rs863225310) as “With Pathogenic allele”, InSiGHT Colon Cancer Gene Variant Database (LOVD), ClinVar database (classified as pathogenic by Mayo Clinic). The variant was not identified in the 1000 Genomes Project, the NHLBI Exome Sequencing Project, the Exome Aggregation Consortium, the genome Aggregation Database (beta), Clinvitae database (classifications), COSMIC, Zhejiang Colon Cancer Database (LOVD), GeneInsight - COGR database and UMD database. The c.1312+1G>A variant is predicted to cause abnormal splicing because the nucleotide substitution occurs in the invariant region of the splice consensus sequence. In addition, 5 of 5 in silico or computational prediction software programs (SpliceSiteFinder, MaxEntScan, NNSPLICE, GeneSplicer, HumanSpliceFinder) predict a greater than 10% difference in splicing. In summary, based on the above information, this variant meets our laboratory’s criteria to be classified as pathogenic. -

not provided Pathogenic:1

Pathogenic, no assertion criteria provided

research

Mayo Clinic Laboratories, Mayo Clinic

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Hereditary cancer-predisposing syndrome Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Ambry Genetics

Apr 18, 2022

The c.1312+1G>A intronic pathogenic mutation results from a G to A substitution one nucleotide after coding exon 9 of the APC gene. This mutation has been detected in multiple families with a classic FAP phenotype (Gavert N et al, Hum. Mutat. 2002 Jun; 19(6):664; Kerr SE, J Mol Diagn 2013 Jan; 15(1):31-43). In one study, in addition to being detected in an affected father and his two affected sons, mRNA analysis confirmed that that mutation leads to an aberrantly spliced transcript with a premature stop codon (Zhang S, Gene 2016 Feb; 577(2):187-92). In silico splice site analysis predicts that this alteration will weaken the native splice donor site. In addition to the clinical data presented in the literature, alterations that disrupt the canonical splice site are expected to cause aberrant splicing, resulting in an abnormal protein or a transcript that is subject to nonsense-mediated mRNA decay. As such, this alteration is classified as a disease-causing mutation. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Pathogenic	0.37
CADD	Pathogenic	34
DANN	Uncertain	1.0
Eigen	Pathogenic	1.3
Eigen_PC	Pathogenic	1.1
FATHMM_MKL	Pathogenic	1.0	D
MutationTaster	Benign	1.0	D;D;D
GERP RS		5.8

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.94
SpliceAI score (max)		0.98		Details are displayed if max score is > 0.2
DS_DL_spliceai		0.98		Position offset: -1

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

Publications

LitVar

Other links and lift over

dbSNP: rs863225310; hg19: chr5-112155042; COSMIC: COSV57343038; COSMIC: COSV57343038;