Rapid screening test of most frequent BRCA1/BRCA2 pathogenic variants in the NGS era

The average risk of breast cancer in general Slovak population of women is 4-5% and the risk of ovarian cancer is 2%. Probability of breast/ovarian cancer development is higher in individuals carrying a causative germline DNA variant in BRCA1 or BRCA2 gene responsible for hereditary breast/ovarian cancer (HBOC). Although a major proportion of inherited breast/ovarian cancers are due to the mentioned causal mutations, a number of new genes have emerged. Here we describe a rapid, multiplex and comprehensive approach for the detection of pathogenic variants in BRCA1 and BRCA2 genes which most frequently occur in Slovak HBOC population. Analysis comprises the combination of mutation specific methods. Fluorescent PCR amplification followed by fragment analysis for detection of insertions/deletions in exon 11 of BRCA1 gene. Second method is SNaPshot analysis for detection of the most frequent missense and ins/del variants in exons 2, 5, 13, 20 of BRCA1 and exons 11, 23 and 25 of BRCA2 gene. Altogether, we have analyzed 687 samples, 86 (12.5%) in group 1, which fulfilled indication criteria based on the positive family/personal history. Group 2 involved 601 (87.5%) cases, who did not meet the indication criteria and only the screening test was recommended. Using the combined approach, we have identified 47 mutated samples (6.8%), 40 in group 1 (46.5%) and 7 in group 2 (1.1%). However, the presented screening test would not provide complex results of BRCA1/2 gene analysis, it offers testing accessible to a broader spectrum of individuals under the threshold of indication for whole gene analysis. This approach may provide valuable information even in the NGS analysis era.