rs78847145

Positions:

• chr5-112792445-G-A
• chr5-112792445-G-C
• chr5-112792445-G-T

Variant summary

Our verdict is Pathogenic. Variant got 16 ACMG points: 16P and 0B. PVS1_Moderate PM2 PP3_Strong PP5_Very_Strong

The NM_000038.6(APC):​c.646-1G>A variant causes a splice acceptor change. 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_acceptor
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:5
• Conservation: PhyloP100: 6.92

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 16 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, product NOT destroyed by NMD, known LOF gene, truncates exone, which is 0.009728082 fraction of the gene. No cryptic splice site detected. Exon removal is inframe change.
• PM2: Very rare variant in population databases, with high coverage
• PP3: Splicing scoreres supports a deletorius effect: Scorers claiming Pathogenic: dbscSNV1_ADA, dbscSNV1_RF, max_spliceai. No scorers claiming Uncertain. No scorers claiming Benign.
• PP5: Variant 5-112792445-G-A is Pathogenic according to our data. Variant chr5-112792445-G-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 1297545.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr5-112792445-G-A is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
APC	NM_000038.6	c.646-1G>A		splice_acceptor_variant		ENST00000257430.9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
APC	ENST00000257430.9	c.646-1G>A		splice_acceptor_variant		5	NM_000038.6	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 29

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:5

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Familial adenomatous polyposis 1 Pathogenic:2

Likely pathogenic, criteria provided, single submitter	clinical testing	Invitae	Aug 03, 2021	In summary, the currently available evidence indicates that the variant is pathogenic, but additional data are needed to prove that conclusively. Therefore, this variant has been classified as Likely Pathogenic. Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. Disruption of this splice site has been observed in individual(s) with familial adenomatous polyposis (PMID: 8990002, 31062380, 31113927). This variant is not present in population databases (ExAC no frequency). This sequence change affects an acceptor splice site in intron 6 of the APC gene. It is expected to disrupt RNA splicing. Variants that disrupt the donor or acceptor splice site typically lead to a loss of protein function (PMID: 16199547), and loss-of-function variants in APC are known to be pathogenic (PMID: 17963004, 20685668). -
Likely pathogenic, criteria provided, single submitter	clinical testing	Myriad Genetics, Inc.	Apr 27, 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. -

not provided Pathogenic:2

Pathogenic, no assertion criteria provided	clinical testing	Clinical Genetics DNA and cytogenetics Diagnostics Lab, Erasmus MC, Erasmus Medical Center	-	- -
Pathogenic, no assertion criteria provided	clinical testing	Joint Genome Diagnostic Labs from Nijmegen and Maastricht, Radboudumc and MUMC+	-	- -

Hereditary cancer-predisposing syndrome Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Ambry Genetics

Jun 04, 2021

The c.646-1G>A intronic pathogenic mutation results from a G to A substitution one nucleotide before coding exon 6 of the APC gene. This mutation has been detected in multiple familial adenomatous polyposis (FAP) patients and families (van der Luijt et al. Hum Mutat. 1997;9(1):7-16; Crobach S et al. Fam. Cancer 2012 Dec; Tsukanov AS et al. Russian Journal of Genetics, 2017;53(3):369-75). In addition, this mutation was detected in an Italian individual diagnosed with FAP who had a personal history of duodenal cancer, osteoma, and a desmoid tumor. cDNA analysis indicated that this mutation causes aberrant splicing and leads to a premature stop codon at codon 292 (Aceto et al. Hum Mutat. 2005 Oct;26(4):394). 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	0.36
CADD	Pathogenic	36
DANN	Uncertain	1.0
Eigen	Pathogenic	1.1
Eigen_PC	Pathogenic	0.99
FATHMM_MKL	Pathogenic	0.98	D
MutationTaster	Benign	1.0	D;D;D
GERP RS		5.2

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.94
SpliceAI score (max)		1.0		Details are displayed if max score is > 0.2
DS_AG_spliceai		0.85		Position offset: 11
DS_AL_spliceai		1.0		Position offset: 1

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

Publications

No publications associated with this variant yet.

Other links and lift over

hg19: chr5-112128142; COSMIC: COSV57347627;