ClinVar

Description

The p.Thr77Thr variant has been identified in 22 out of 1134 proband chromosomes (frequency 0.019) in individuals with breast and ovarian cancer phenotype, and was not identified in 300 control chromosomes (Cherbal 2010, Hadjisawas 2004, Hadjisawas 2003, Fackenthal 2011, Baumbach-abstract). However, it is listed in dbSNP database (ID#: rs114446594) with an average heterozygosity of 0.005+/-0.051, therefore increasing the likelihood of this variant to be benign. This variant is not expected to have clinical significance because it does not alter an amino acid residue, and is not located near a splice junction. In the UMD database, this variant has been identified in 3 (out of 10) individuals with breast or ovarian cancers, where a second pathogenic BRCA1 or BRCA2 mutation was also detected, suggesting that this is a benign variant. In a recent study, partial exon 3 skipping was suggested to be associated with this variant, however this information is not very predictive of pathogenicity (Thery 2011). In summary, based on above information we would lean towards a more benign role for this variant, therefore this variant is classified as Benign.