The yield of full BRCA1/2 genotyping in Israeli Arab high-risk breast/ovarian cancer patients.

Abstract

While the spectrum of germline mutations in BRCA1/2 genes in the Israeli Jewish population has been extensively studied, there is a paucity of data pertaining to Israeli Arab high-risk cases. Consecutive Israeli Arab breast and/or ovarian cancer patients were recruited using an ethically approved protocol from January 2012 to February 2019. All ovarian cancer cases were referred for BRCA genotyping. Breast cancer patients were offered BRCA sequencing and deletion/duplication analysis after genetic counseling, if the calculated risk for carrying a BRCA mutation by risk prediction algorithms was ≥10%. Overall, 188 patients participated; 150 breast cancer cases (median age at diagnosis: 40years, range 22-67) and 38 had ovarian cancer (median age at diagnosis: 52.5years, range 26-79). Of genotyped cases, 18 (10%) carried one of 12 pathogenic or likely-pathogenic variants, 12 in BRCA1, 6 in BRCA2. Only one was a rearrangement. Three variants recurred in more than one case; one was detected in five seemingly unrelated families. The detection rate for all breast cancer cases was 4%, 5% in bilateral breast cancer cases and 3% if breast cancer was diagnosed < 40years. Of patients with ovarian cancer, 12/38 (32%) were carriers; the detection rate reached 75% (3/4) among patients diagnosed with both breast and ovarian cancer. The overall yield of comprehensive BRCA1/2 testing in high-risk Israeli Arab individuals is low in breast cancer patients, and much higher in ovarian cancer patients. These results may guide optimal cancer susceptibility testing strategy in the Arab-Israeli population.