ClinVar Genomic variation as it relates to human health

This variant is denoted BRCA2 c.9052A>G at the cDNA level, p.Ser3018Gly (S3018G) at the protein level, and results in the change of a Serine to a Glycine (AGT>GGT). Using alternate nomenclature, this variant would be defined as BRCA2 9280A>G. This variant has not, to our knowledge, been published in the literature as pathogenic or benign. BRCA2 Ser3018Gly was not observed in large population cohorts (Lek 2016). This variant is located in the DNA binding domain (Yang 2002). In silico analysis, which includes splice predictors and evolutionary conservation, supports that this variant does not alter protein structure/function. Based on currently available information, it is unclear whether BRCA2 Ser3018Gly is pathogenic or benign. We consider it to be a variant of uncertain significance.

To the best of our knowledge, this variant has not been reported in the published literature. It also has not been reported in large, multi-ethnic general populations (Genome Aggregation Database, http://gnomad.broadinstitute.org). However, this variant has been reported to result in aberrant splicing and partial exon skipping. 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.

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. Studies have shown that this missense change results in activation of a cryptic splice site and introduces a premature termination codon (Invitae). The resulting mRNA is expected to undergo nonsense-mediated decay. 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. ClinVar contains an entry for this variant (Variation ID: 96877). This variant has not been reported in the literature in individuals affected with BRCA2-related conditions. This variant is not present in population databases (gnomAD no frequency). This sequence change replaces serine, which is neutral and polar, with glycine, which is neutral and non-polar, at codon 3018 of the BRCA2 protein (p.Ser3018Gly). RNA analysis indicates that this missense change induces altered splicing and may result in an absent or disrupted protein product.

The c.9052A>G variant (also known as p.S3018G), located in coding exon 22 of the BRCA2 gene, results from an A to G substitution at nucleotide position 9052. The serine at codon 3018 is replaced by glycine, an amino acid with similar properties. This amino acid position is not well conserved in available vertebrate species. This nucleotide position is well conserved in available vertebrate species. In silico splice site analysis predicts that this alteration 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). Based on the majority of available evidence to date, this variant is likely to be pathogenic.