New recurrent BRCA1/2 mutations in Polish patients with familial breast/ovarian cancer detected by next generation sequencing

Anna Kluska, Aneta Balabas, Agnieszka Paziewska, Maria Kulecka, Dorota Nowakowska, Michal Mikula, Jerzy Ostrowski

Targeted PCR-based genetic testing for BRCA1 and BRCA2 can be performed at a lower cost than full gene testing; however, it does not detect mutations responsible for familial breast and/or ovarian cancers. In the present study, we report the utility of next generation sequencing (NGS) to identify new pathogenic variants of BRCA1/2. BRCA1 and BRCA2 exons were amplified using the Ion AmpliSeq BRCA1/2 Panel and sequenced on the Ion Torrent PGM sequencer in 512 women with familial and/or only early onset breast and/or ovarian cancers who were negative for selected BRCA1/2 mutations. 146 single nucleotide variants (SNVs) and 32 indels were identified. Of them, 14 SNVs and 17 indels were considered as pathogenic or likely pathogenic. One and 18 pathogenic mutations had been detected previously in the Polish and other populations, respectively, and 12 deleterious mutations were previously unknown. Eight mutations were recurrent; Q563X (BRCA1), N3124I (BRCA2) and c.4516delG (BRCA1) were found in eight, six and four patients, respectively, and two other mutations (c.9118-2A > G and c.7249delCA in BRCA2) were detected in three patients each. Altogether, BRCA1/2 pathogenic mutations were identified in 52 out of 512 (10%) patients. NGS substantially improved the detection rates of a wide spectrum of mutations in Polish patients with familial breast and/or ovarian cancer. Although targeted screening for specific BRCA1 mutations can be offered to all Polish breast or ovarian cancer patients, NGS-based testing is justified in patients with breast or ovarian cancer likely related to BRCA1/2 who test negative for the selected BRCA1/2 pathogenic mutations.