Description
The APC p.Val609Ile variant was identified in 5 of 8718 proband chromosomes (frequency: 0.0006) from individuals or families with colorectal cancer (Kerr 2012, Pearlman 2017, Yurgelun 2015, Yurgelun 2017). The variant was also identified in dbSNP (ID: rs147863331) as "With other allele", ClinVar (classified as likely benign by Invitae, GeneDx, Ambry Genetics and three other submitters; as uncertain significance by Counsyl), and in LOVD 3.0 (1x as VUS). The variant was not identified in UMD-LSDB. The variant was identified in control databases in 83 of 277028 chromosomes at a frequency of 0.0003 increasing the likelihood this could be a low frequency benign variant (Genome Aggregation Database Feb 27, 2017). The variant was observed in the African population in 83 of 24034 chromosomes (freq: 0.003), while the variant was not observed in the Other, Latino, European, Ashkenazi Jewish, East Asian, Finnish, and South Asian populations. The variant was identified in our laboratory with a co-occurring pathogenic APC variant (c.4391_4394del, p.Glu1464Valfs*8), increasing the likelihood that the p.Val609Ile variant does not have clinical significance. The p.Val609 residue is conserved across mammals and other organisms, and four out of five computational analyses (PolyPhen-2, SIFT, AlignGVGD, BLOSUM, MutationTaster) suggest that the variant may impact the protein; however, this information is not predictive enough to assume pathogenicity. The variant occurs outside of the splicing consensus sequence and in silico or computational prediction software programs (SpliceSiteFinder, MaxEntScan, NNSPLICE, GeneSplicer) do not predict a difference in splicing. In summary, based on the above information the clinical significance of this variant cannot be determined with certainty at this time although we would lean towards a more benign role for this variant. This variant is classified as likely benign.
# | Sample | Method | Observation |
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Origin | Affected | Number tested | Tissue | Purpose | Method | Individuals | Allele frequency | Families | Co-occurrences |
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1 | unknown | yes | not provided | not provided | not provided | | not provided | not provided | not provided | not provided |