ClinVar Genomic variation as it relates to human health

In the published literature, this variant has been reported in individuals/families with history of breast and/or ovarian cancer (PMID: 30606148 (2019), 28338653 (2017), 10755399 (2000)). In a large scale breast cancer association study, the variant was observed individuals with breast cancer as well unaffected control individuals (PMID: 33471991 (2021), see also LOVD (http://databases.lovd.nl/shared/genes/BRCA2)). The frequency of this variant in the general population, 0.00044 (8/18378 chromosomes in East Asian subpopulation (Genome Aggregation Database, http://gnomad.broadinstitute.org)), is higher than would generally be expected for pathogenic variants in this gene. Analysis of this variant using bioinformatics tools for the prediction of the effect of amino acid changes on protein structure and function yielded predictions that this variant is benign. Based on the available information, we are unable to determine the clinical significance of this variant.

This alteration is classified as likely benign based on a combination of the following: seen in unaffected individuals, population frequency, intact protein function, lack of segregation with disease, co-occurrence, RNA analysis, in silico models, amino acid conservation, lack of disease association in case-control studies, and/or the mechanism of disease or impacted region is inconsistent with a known cause of pathogenicity.

This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score, this variant could not be ruled out of causing disease and therefore its association with disease required further investigation. A literature search was performed for the gene, cDNA change, and amino acid change (if applicable). No publications were found based on this search. This variant was therefore classified as a variant of unknown significance for this disease.

This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score, this variant could not be ruled out of causing disease and therefore its association with disease required further investigation. A literature search was performed for the gene, cDNA change, and amino acid change (if applicable). No publications were found based on this search. This variant was therefore classified as a variant of unknown significance for this disease.

This missense variant replaces asparagine with serine at codon 108 of the BRCA2 protein. Computational prediction suggests that this variant may not impact protein structure and function (internally defined REVEL score threshold <= 0.5, PMID: 27666373). To our knowledge, functional studies have not been reported for this variant. This variant has been reported in one individual each affected with breast cancer, ovarian cancer and ductal carcinoma in situ (PMID: 10755399, 28338653, 30606148) and a suspected HBOC family (PMID: 21702907). In a large breast cancer case-control meta-analysis conducted by the BRIDGES consortium, this variant was reported in 5/60466 cases and 2/53461 unaffected controls (p-value=0.459) (PMID: 33471991; Leiden Open Variation Database DB-ID BRCA2_007696). This variant has been identified in 8/250556 chromosomes in the general population by the Genome Aggregation Database (gnomAD). The available evidence is insufficient to determine the role of this variant in disease conclusively. Therefore, this variant is classified as a Variant of Uncertain Significance.

In silico analysis supports that this missense variant does not alter protein structure/function; Also known as 551A>G; This variant is associated with the following publications: (PMID: 21702907, 24817641, 32467295, 30606148)

This missense variant replaces asparagine with serine at codon 108 of the BRCA2 protein. Computational prediction suggests that this variant may not impact protein structure and function (internally defined REVEL score threshold <= 0.5, PMID: 27666373). To our knowledge, functional studies have not been reported for this variant. This variant has been reported in one individual each affected with breast cancer, ovarian cancer and ductal carcinoma in situ (PMID: 10755399, 28338653, 30606148) and a suspected HBOC family (PMID: 21702907). In a large breast cancer case-control meta-analysis conducted by the BRIDGES consortium, this variant was reported in 5/60466 cases and 2/53461 unaffected controls (p-value=0.459) (PMID: 33471991; Leiden Open Variation Database DB-ID BRCA2_007696). This variant has been identified in 8/250556 chromosomes in the general population by the Genome Aggregation Database (gnomAD). The available evidence is insufficient to determine the role of this variant in disease conclusively. Therefore, this variant is classified as a Variant of Uncertain Significance.

This sequence change replaces asparagine, which is neutral and polar, with serine, which is neutral and polar, at codon 108 of the BRCA2 protein (p.Asn108Ser). This variant is present in population databases (rs80358568, gnomAD 0.04%). This missense change has been observed in individual(s) with breast and/or ovarian cancer (PMID: 30606148, 35918668). ClinVar contains an entry for this variant (Variation ID: 51430). Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is not expected to disrupt BRCA2 protein function with a negative predictive value of 95%. In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance.

The BRCA2 p.Asn108Ser variant was not identified in the literature. The variant was identified in dbSNP (ID: rs80358568) “With uncertain significance allele”, Exome Aggregation Consortium (ExAC) database, the ClinVar database (classified as a uncertain significance variant by the Sharing Clinical Reports Project, derived from Myriad reports; BIC and Ambry Genetics) and the BIC database (2X with unknown clinical importance). This variant was identified in the Exome Aggregation Consortium (ExAC) database (released Oct 20th, 2014) in 3 of 8278 chromosomes (frequency: 0.0004) from a population of East Asian individuals, although this low number of observations and low frequency is not substantive enough to determine the prevalence of the variant in the general population and its relationship to disease. The p.Asn108Ser residue is not conserved in mammals and computational analyses (PolyPhen-2, SIFT, AlignGVGD, BLOSUM, MutationTaster) do not suggest a high likelihood of impact to the protein. However, this information is not predictive enough to rule out pathogenicity. The variant occurs outside of the splicing consensus sequence and one of five in-silico or computational prediction software programs (SpliceSiteFinder, MaxEntScan, NNSPLICE, GeneSplicer, HumanSpliceFinder) predicted 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. This variant is classified as a variant of unknown significance.