ClinVar Genomic variation as it relates to human health

RAD50 has only recently been described in association with cancer predisposition and the risks are not well understood. This variant is denoted RAD50 c.943G>T at the cDNA level, p.Val315Leu (V315L) at the protein level, and results in the change of a Valine to a Leucine (GTA>TTA). This variant has been published in two individuals with familial breast cancer and in two with multiple primaries including laryngeal cancer (Tommiska 2006, Zió Kowska-Suchanek 2013). RAD50 Val315Leu was also reported in one healthy control in Zió Kowska-Suchanek et al (2013). This variant was observed with an allele frequency of 0.3% (23/8600) in European Americans in the NHLBI Exome Sequencing Project, not frequent enough to be considered a polymorphism. This variant is a conservative substitution of one neutral non-polar amino acid for another, altering a position that is well conserved throughout evolution and is located in the coiled-coil region per UniProt. In silico analyses predict this variant to have a benign effect on protein structure and function. At a molecular level, the impact of this missense variant on protein structure and function is not known and thus we consider this to be a variant of uncertain significance. Furthermore, based on the currently available information, cancer risks associated with this variant, and the RAD50 gene, remain unclear.

Variant summary: RAD50 c.943G>T (p.Val315Leu) results in a conservative amino acid change in the encoded protein sequence. Three of five in-silico tools predict a benign effect of the variant on protein function. The variant allele was found at a frequency of 0.0012 in 251062 control chromosomes. The observed variant frequency is approximately 19 fold of the estimated maximal expected allele frequency for a pathogenic variant in RAD50 causing Hereditary Breast And Ovarian Cancer Syndrome phenotype (6.3e-05), strongly suggesting that the variant is benign. c.943G>T has been reported in the literature in individuals affected with a variety of cancers such as breast cancer, multiple primary tumors as well as unaffected control cohorts (example, Harvey_2017, Tommiska_2006, Young_2016, Ziolkowska-Suchanek_2013). These report(s) do not provide unequivocal conclusions about association of the variant with Hereditary Breast And Ovarian Cancer Syndrome. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. Three clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014 without evidence for independent evaluation (benign, n=1, likely benign, n=1, VUS, n=1). Based on the evidence outlined above, the variant was classified as benign.

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.