Clinically Significant Unclassified Variants in BRCA1 and BRCA2 genes among Korean Breast Cancer Patients

Unclassified variants (UVs) of and genes are not defined as pathogenic for breast cancer, and their clinical significance currently remains undefined. Therefore, this study was conducted to identify potentially pathogenic UVs by comparing their prevalence between breast cancer patients and controls. A total of 328 breast cancer patients underwent genetic screening at the National Cancer Center of Korea. Genetic variants of genes that were categorized as unclassified according to the Breast Cancer Information Core database were selected based on allelic frequency, after which candidate variants were genotyped in 421 healthy controls. We also examined family members of the study participants. Finally, the effects of amino acid substitutions on protein structure and function were predicted . Genetic tests revealed 33 UVs in and 47 in . Among 15 candidates genotyped in healthy controls, c.5339T>C in BRCA1 and c.6029T>G, c.7522G>A in BRCA2 were not detected. Moreover, the c.5339T>C variant in the gene was detected in four patients with a family history of breast cancer. This nonsynonymous variant (Leu1780Pro) in the BRCA1 C-terminal domain was predicted to have an effect on BRCA1 protein structure/function. This study showed that comparison of genotype frequency between cases and controls could help identify UVs of genes that are potentially pathogenic. Moreover, ourfindings suggest that c.5339T>C in might be a pathogenic variant for patients and their families.