Germline Pathogenic Variants in Breast Cancer-Predisposing Genes Among Early-Onset Female and Male Breast Cancer in Ethiopia.

Abstract

Patients with breast cancer in Ethiopia are generally diagnosed with late-stage disease, and there is a high proportion of young female and male patients. The role of genetic predisposition is yet unknown in this setting. To increase the knowledge about hereditary breast cancer in Ethiopia, this study investigated germline pathogenic variants (PVs) in breast cancer-predisposing genes in a high-risk cohort of young women and men with breast cancer. One hundred women (age 18-39) and men (all ages) diagnosed with breast cancer at the Tikur Anbessa Specialized Hospital, Addis Ababa, were included. Basic patient and tumor characteristics, and family history were collected, and blood samples drawn. DNA was extracted locally before transport to Lund University, Sweden, for DNA analysis using next-generation sequencing. Type and frequency of PVs in breast cancer-related genes (<i>ATM, BARD1, BRCA1, BRCA2, CDH1, CHEK2, PALB2, PTEN, RAD51C, RAD51D, STK11</i>, and <i>TP53</i>) were analyzed. A high proportion of the 89 study participants with successful genetic analysis carried PVs in breast cancer susceptibility genes (23.6%; 95% CI 15.2 to 33.8). In total, 22 PVs were detected in <i>BRCA1</i> (n = 7), <i>BRCA2</i> (n = 8), <i>PALB2</i> (n = 4), <i>BARD1</i> (n = 1), <i>PTEN</i> (n = 1), and <i>ATM</i> (n = 1). Potential founder variants and two novel PVs were found (<i>BRCA1</i> c.5278-864_5332+621del and <i>PALB2</i> c.1169_1170del). Genetic predisposition plays an important role among young women and men in the study setting, with nearly one in four patients carrying a PV. The results call for further research and interventions targeting individuals at high risk, with the long-term potential of reduced morbidity and mortality.