ClinVar

Description

The BRCA2 p.Trp2626Cys variant was identified in 4 of 7208 proband chromosomes (frequency: 0.0006) from individuals or families with contralateral and unilateral breast cancers, and was not identified in 2996 control chromosomes from healthy individuals (Borg 2010 PMID:20104584, Pruss 2014 PMID:25085752, Capanu 2011 PMID:21520273, Petersen 2016 PMID:26733283). The variant has also been identified in at least one patient with Fanconi anemia who also harboured a BRCA2 frameshift pathogenic variant (Stoepker 2015 PMID:25583207). In a study done to classify unknown variants, the variant was submitted to web-based algorithms using Align-GVGD, Grantham Variation and Grantham Deviation scores and found to be class (C65) of substitutions, which is most likely to interfere with function and was scored as possibly deleterious (Borg 2010 PMID:20104584). Furthermore studies classified the variant as deleterious based on a loss of DNA repair function identified through function studies (Biswas 2011 PMID:21719596, Guidugli 2013 PMID: 23108138, Hendriks 2014 PMID:25146914). The variant was shown to be sensitive to PARP inhibitors when present in a cell line derived from a patient with Fanconi anemia (Stoepker 2015). In addition Lindor et al. 2011 (PMID:21990134) determined the variant to be pathogenic (48.14 possibility of causality) when they weighted together segregation data, co-occurrence with pathogenic variants, personal and family history, and tumor pathology. However the above study by Biswas et al. 2011 demonstrated that the variant may be hypomorphic as it was able to recuse lethality in embryonic stem cells (notably in a similar experiment in the Hendrick et al. study the variant did not rescue lethality), and Pruss et al. 2014 also classified the variant as hypomorphic based on clinic history weighting algorithm. The variant was identified in dbSNP (ID: rs80359013 “With Pathogenic Allele”, in 1000 Genomes Project in 2 of 100000 chromosomes (frequency: 0.00002). The variant was also identified in the Exome Aggregation Consortium database (released Mar 14, 2016) in 2 of 121350 chromosomes (frequency: 0.00002) from a population of 2 of 66726 (0.00003) of European (Non-Finnish) alleles, 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 variant was also identified in GeneInsight-COGR by Trillum Health Partners 1x as Class 5, in Clinvar (pathogenic by ENIGMA, Quest, CIMBA, Counsyl, LMM, and Invitae, AND as likely pathogenic by LabCorp, GeneDx, Oslo University, Ambry, SCRP, and Medical University Innsbruck as well as Uncertain Significance by BIC). The variant is further identified in the BIC database 14X with unknown clinical importance, in the ARUP Laboratories BRCA Mutations Database 1x as definitely pathogenic, in the Fanconi Anemia Mutation Database (LOVD) 2x as predicted deleterious and 1x with reduced complementation. The variant was not listed in the COSMIC, MutDB, and UMD databases. The p.Trp2626 residue is conserved across mammals and other organisms, and 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, HumanSpliceFinder) 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 pathogenic role for this variant. This variant is classified as likely pathogenic.