rs587781809
Variant summary
Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PVS1PM2PP5_Very_Strong
The NM_000038.6(APC):c.220+2T>A variant causes a splice donor, intron change. The variant allele was found at a frequency of 0.00000125 in 1,603,200 control chromosomes in the GnomAD database, with no homozygous occurrence. 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
Consequence
NM_000038.6 splice_donor, intron
Scores
Clinical Significance
Conservation
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ACMG classification
Verdict is Pathogenic. Variant got 18 ACMG points.
Transcripts
RefSeq
Ensembl
Frequencies
GnomAD3 genomes AF: 0.00000657 AC: 1AN: 152158Hom.: 0 Cov.: 32
GnomAD4 exome AF: 6.89e-7 AC: 1AN: 1451042Hom.: 0 Cov.: 27 AF XY: 0.00000138 AC XY: 1AN XY: 722746
GnomAD4 genome AF: 0.00000657 AC: 1AN: 152158Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0AN XY: 74342
ClinVar
Submissions by phenotype
Familial adenomatous polyposis 1 Pathogenic:3
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. -
Criteria applied: PVS1,PS4_MOD,PM2_SUP -
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 altered protein product. This variant is not present in population databases (gnomAD no frequency). Disruption of this splice site has been observed in individual(s) with clinical features of familial adenomatous polyposis (PMID: 23159591). ClinVar contains an entry for this variant (Variation ID: 141515). Studies have shown that disruption of this splice site results in activation of a cryptic splice site, and produces a non-functional protein and/or introduces a premature termination codon (internal data). For these reasons, this variant has been classified as Pathogenic. -
not provided Pathogenic:3
PVS1_Mod, PM2, PP4, PP5 -
This variant is located in a canonical splice-donor site and interferes with normal APC mRNA splicing. The variant has been reported in individuals affected with Familial Adenomatous Polyposis (FAP) and atypical Familial Adenomatous Polyposis (AFAP) in the published literature (PMID: 23159591 (2013), 14574009 (2001)). Therefore, the variant is classified as pathogenic. -
Canonical splice site variant in a gene for which loss-of-function is a known mechanism of disease; Observed in individuals undergoing APC testing in published literature (Kerr et al., 2013); Not observed at significant frequency in large population cohorts (gnomAD); This variant is associated with the following publications: (PMID: 23159591) -
Hereditary cancer-predisposing syndrome Pathogenic:2
The c.220+2T>A pathogenic intronic variant results from a T to A substitution two nucleotides after coding exon 2 in the APC gene. This alteration was reported in one individual undergoing clinical APC analysis. It was reported to have an allele frequency of 0.003%, and was considered to be pathogenic by the study authors; however clinical data for this individual was not provided and functional analyses were not performed in this study (Kerr SE et al. J Mol Diagn 2013 Jan; 15(1):31-43). This alteration has been observed in multiple individuals who have a personal and/or family history that is consistent with attenuated FAP (Ambry internal data). This nucleotide position is highly conserved in available vertebrate species. 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 that this alteration results in abnormal splicing in the set of samples tested (Ambry internal data). This variant is considered to be rare based on population cohorts in the Genome Aggregation Database (gnomAD). 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. -
This variant causes a T>A nucleotide substitution at the +2 position of intron 3 of the APC gene. Splice site prediction tools predict that this variant may have a significant impact on RNA splicing. To our knowledge, functional studies have not been reported for this variant. This variant has not been reported in individuals affected with hereditary cancer in the literature. This variant has not been identified in the general population by the Genome Aggregation Database (gnomAD). Loss of APC function is a known mechanism of disease (clinicalgenome.org). Based on the available evidence, this variant is classified as Likely Pathogenic. -
Carcinoma of colon Pathogenic:1
The APC c.220+2T>A variant was identified in HGMD, but was not identified in the literature. The variant is predicted to cause abnormal splicing because the nucleotide substitution occurs in the invariant region of the 5' splice consensus sequence. In addition, four in silico or computational prediction software programs (SpliceSiteFinder, MaxEntScan, NNSPLICE, 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. -
Computational scores
Source:
Splicing
Find out detailed SpliceAI scores and Pangolin per-transcript scores at