5-112766411-G-A

Position:

• chr5-112766411-G-A

Variant summary

Our verdict is Pathogenic. Variant got 10 ACMG points: 10P and 0B. PVS1 PS4_Supporting PM2_Supporting

This summary comes from the ClinGen Evidence Repository: The NM_000038.6:c.220+1G>A variant in APC occurs within the canonical splice donor site (+1) of intron 3. It is predicted to cause skipping of exon 3, resulting in a frameshift in a gene in which loss-of-function is an established disease mechanism (PVS1). This prediction is confirmed by RNA analysis (internal data from Ambry Genetics and Invitae). This variant has been reported in one family meeting phenotypic criteria, resulting in a total phenotype score of 1 (PS4_supporting, [internal data from Ambry Genetics]). This variant is absent from gnomAD v2.1.1 (PM2_supporting). In summary, this variant meets the criteria to be classified as Pathogenic for autosomal-dominant inherited FAP based on the ACMG/AMP criteria applied, as specified by the HCCP VCEP: criteria PVS1, PS4_supporting and PM2_supporting applied (VCEP specifications v2.1.0; date of approval 11/24/2023). LINK:https://erepo.genome.network/evrepo/ui/classification/CA360617465/MONDO:0021056/089

• Frequency: Genomes: not found (cov: 32)
• Consequence: APC NM_000038.6 splice_donor, intron
• Scores: Splicing: ADA: 0.9999
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:4
• Conservation: PhyloP100: 8.68

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 10 ACMG points.

• PVS1: For more information check the summary or visit ClinGen Evidence Repository.
• PS4: For more information check the summary or visit ClinGen Evidence Repository.
• PM2: For more information check the summary or visit ClinGen Evidence Repository.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
APC	NM_000038.6	c.220+1G>A		splice_donor_variant, intron_variant		ENST00000257430.9	NP_000029.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
APC	ENST00000257430.9	c.220+1G>A		splice_donor_variant, intron_variant		5	NM_000038.6	ENSP00000257430.4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 27

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:4

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Familial adenomatous polyposis 1 Pathogenic:3

Pathogenic, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Aug 24, 2023	For these reasons, this variant has been classified as Pathogenic. Studies have shown that disruption of this splice site results in skipping of exon 3 and/or activation of a cryptic splice site and introduces a premature termination codon (Invitae). The resulting mRNA is expected to undergo nonsense-mediated decay. ClinVar contains an entry for this variant (Variation ID: 433598). Disruption of this splice site has been observed in individual(s) with familial adenomatous polyposis (Invitae). This variant is not present in population databases (gnomAD no frequency). This sequence change affects a donor splice site in intron 3 of the APC gene. RNA analysis indicates that disruption of this splice site induces altered splicing and may result in an absent or disrupted protein product. -
Likely pathogenic, criteria provided, single submitter	clinical testing	Myriad Genetics, Inc.	Jun 10, 2024	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, no assertion criteria provided	clinical testing	Department of Pathology and Laboratory Medicine, Sinai Health System	-	The APC c.220+1G>A variant was not identified in the literature, nor was it identified in the dbSNP, NHLBI Exome Sequencing Project, HGMD, UMD, “InSiGHT Colon Cancer Database”, or COSMIC database. The variant is predicted to cause abnormal splicing because the nucleotide substitution occurs in the invariant +1 position of the splice consensus sequence; in addition, four in silico or computational prediction software programs (SpliceSiteFinder, MaxEntScan, NNSPLICE, HumanSpliceFinder) predict a difference in splicing. In summary, based on the above information, this variant meets our laboratory’s criteria to be classified as pathogenic. -

Hereditary cancer-predisposing syndrome Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Ambry Genetics

Nov 17, 2020

The c.220+1G>A intronic pathogenic mutation results from a G to A substitution one nucleotide after coding exon 2 of the APC gene. This variant was not reported in population-based cohorts in the Genome Aggregation Database (gnomAD). In silico splice site analysis predicts that this alteration will weaken the native splice donor site and will result in the creation or strengthening of a novel splice donor site. RNA studies have demonstrated this alteration results in abnormal splicing in the set of samples tested (Ambry internal data). This alteration has been observed in at least one individual who has a personal or family history that is consistent with APC-associated disease (Ambry internal data). 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. Based on the supporting evidence, this alteration is interpreted as a disease-causing mutation. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Uncertain	0.050
CADD	Pathogenic	35
DANN	Uncertain	0.98
Eigen	Pathogenic	0.86
Eigen_PC	Pathogenic	0.69
FATHMM_MKL	Pathogenic	1.0	D
GERP RS		4.8

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.91
SpliceAI score (max)		0.99		Details are displayed if max score is > 0.2
DS_DG_spliceai		0.68		Position offset: 14
DS_DL_spliceai		0.99		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: rs1554069570; hg19: chr5-112102108;