rs863225370

Positions:

Variant summary

Our verdict is Likely pathogenic. Variant got 7 ACMG points: 7P and 0B. PVS1_ModeratePM2_SupportingPS4

This summary comes from the ClinGen Evidence Repository: The c.645+1G>A variant in APC occurs within the canonical splice donor site +1 of intron 6. It is predicted to result in an inframe skipping of exon 6 (PVS1_Moderate). The results from ≥2 in silico splicing predictors (SpliceAI, MaxEntScan, VarSeak) indicate that this variant may affect splicing by disrupting the donor splice site of intron 6 (PP3 supplanted by PVS1_Moderate). RT-PCR of patient blood demonstrated that the variant impacts splicing by removing exon 6 from the transcript, resulting in an NMD-escaping in-frame event with uncertain impact (PMID:22987206, PS3 supplanted by PVS1_Moderate). This variant has been reported in 9 families with FAP with a total phenotype score of 6 points (PS4; Ambry, Invitae, GeneDX, Barcelona, Edinburgh and Leiden internal data; PMID 22987206; PMID 17411426; PMID 20685668; PMID 8381580). This variant is absent from gnomAD v2.1.1 (PM2_supporting). In summary, this variant meets the criteria to be classified as Likely Pathogenic for FAP based on the ACMG/AMP criteria applied, as specified by the ClinGen InSiGHT Hereditary Colorectal Cancer/Polyposis Variant Curation Expert Panel: PVS1_Moderate, PS4, and PM2_Supporting; (VCEP specifications version 1; date of approval: 12/12/2022). LINK:https://erepo.genome.network/evrepo/ui/classification/CA279701/MONDO:0021056/089

Frequency

Genomes: not found (cov: 33)

Exomes 𝑓: 7.0e-7 ( 0 hom. )

Failed GnomAD Quality Control

Consequence

APC
NM_000038.6 splice_donor, intron

Scores

Splicing: ADA: 1.000

Clinical Significance

Likely pathogenic reviewed by expert panel P:6U:1

Conservation

PhyloP100: 8.99

Variant links:

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]

APC links:

APC (HGNC:):

APC links:

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ACMG classification

Classification made for transcript

Verdict is Likely_pathogenic. Variant got 7 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 linkuse as main transcript	c.645+1G>A		splice_donor_variant, intron_variant		ENST00000257430.9	NP_000029.2	P25054-1Q4LE70

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
APC	ENST00000257430.9 linkuse as main transcript	c.645+1G>A		splice_donor_variant, intron_variant		5	NM_000038.6	ENSP00000257430.4		P25054-1

Frequencies

GnomAD3 genomes

Cov.:

GnomAD4 exome

Data not reliable, filtered out with message: AS_VQSR

AF:

6.96e-7

AC:

AN:

1437060

Hom.:

Cov.:

AF XY:

0.00

AC XY:

AN XY:

716202

show subpopulations

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:

9.17e-7

Gnomad4 OTH exome

AF:

0.00

GnomAD4 genome

Cov.:

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:6Uncertain:1

Revision: reviewed by expert panel

LINK: link

Submissions by phenotype

Familial adenomatous polyposis 1

Pathogenic:3

Pathogenic, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Nov 27, 2023	This sequence change affects a donor 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). This variant is not present in population databases (gnomAD no frequency). Disruption of this splice site has been observed in individuals with familial adenomatous polyposis (PMID: 8381580, 17411426, 20685668, 22987206). ClinVar contains an entry for this variant (Variation ID: 218000). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. For these reasons, this variant has been classified as Pathogenic. -
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. -
Likely pathogenic, reviewed by expert panel	curation	ClinGen InSiGHT Hereditary Colorectal Cancer/Polyposis Variant Curation Expert Panel	Feb 18, 2023	The c.645+1G>A variant in APC occurs within the canonical splice donor site +1 of intron 6. It is predicted to result in an inframe skipping of exon 6 (PVS1_Moderate). The results from more than 2 in silico splicing predictors (SpliceAI, MaxEntScan, VarSeak) indicate that this variant may affect splicing by disrupting the donor splice site of intron 6 (PP3 supplanted by PVS1_Moderate). RT-PCR of patient blood demonstrated that the variant impacts splicing by removing exon 6 from the transcript, resulting in an NMD-escaping in-frame event with uncertain impact (PMID: 22987206, PS3 supplanted by PVS1_Moderate). This variant has been reported in 9 families with FAP with a total phenotype score of 6 points (PS4; Ambry, Invitae, GeneDX, Barcelona, Edinburgh and Leiden internal data; PMID 22987206; PMID 17411426; PMID 20685668; PMID 8381580). This variant is absent from gnomAD v2.1.1 (PM2_supporting). In summary, this variant meets the criteria to be classified as Likely Pathogenic for FAP based on the ACMG/AMP criteria applied, as specified by the ClinGen InSiGHT Hereditary Colorectal Cancer/Polyposis Variant Curation Expert Panel: PVS1_Moderate, PS4, and PM2_Supporting; (VCEP specifications version 1; date of approval: 12/12/2022). -

not provided

Pathogenic:2Uncertain:1

Likely pathogenic, criteria provided, single submitter	clinical testing	GeneDx	Apr 27, 2017	This variant is denoted APC c.645+1G>A or IVS6+1G>A and consists of a G>A nucleotide substitution at the +1 position of intron 6 of the APC gene. This variant destroys a canonical splice donor site and is predicted to cause abnormal gene splicing, leading to either an abnormal message that is subject to nonsense-mediated mRNA decay or to an abnormal protein product. This variant has been reported in individuals with a history of familial adenomatous polyposis (Olschwang 1993, Lagarde 2010). Based on the currently available information, we consider APC c.645+1G>A to be a likely pathogenic variant. -
Uncertain significance, no assertion criteria provided	clinical testing	Department of Pathology and Laboratory Medicine, Sinai Health System	-	- -
Pathogenic, no assertion criteria provided	research	Mayo Clinic Laboratories, Mayo Clinic	-	- -

Hereditary cancer-predisposing syndrome

Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Ambry Genetics

Mar 18, 2019

The c.645+1G>A intronic pathogenic mutation results from a G to A substitution one nucleotide after coding exon 5 of the APC gene. This alteration was identified in 1/934 French patients with familial adenomatous polyposis (FAP) (Lagarde A et al. J. Med. Genet., 2010 Oct;47:721-2), and in a cohort of 160 unrelated patients with FAP (Olschwang S et al. Am. J. Hum. Genet., 1993 Feb;52:273-9). 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

BayesDel_noAF

Pathogenic

0.42

CADD

Pathogenic

DANN

Uncertain

1.0

Eigen

Pathogenic

1.2

Eigen_PC

Pathogenic

1.1

FATHMM_MKL

Pathogenic

1.0

GERP RS

5.6

RBP_binding_hub_radar

0.0

RBP_regulation_power_radar

1.7

Splicing

Name

Calibrated prediction

Score

Prediction

dbscSNV1_ADA

Pathogenic

1.0

dbscSNV1_RF

Pathogenic

0.94

SpliceAI score (max)

0.97

Details are displayed if max score is > 0.2

DS_DG_spliceai

0.39

Position offset: -33

DS_DL_spliceai

0.97

Position offset: -1

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

Publications

LitVar

Below is the list of publications found by LitVar. It may be empty.

Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

LitVar

Other links and lift over