Absence of Germline BRCA1 and BRCA2 Copy Number Variations Among Breast Cancer Patients in the Three Southern Border Provinces of Thailand.

The objective of this study is to investigate germline CNVs in the BRCA1 and BRCA2 genes. Reanalysis of whole-exome sequencing (WES) data from 140 breast cancer (BC) patients originating from Thailand's three southern border provinces was performed using the Genome Analysis Toolkit Germline Copy Number Variant (GATK-gCNV) bioinformatics pipeline. CNVs identified as positive by this pipeline were further validated through multiplex ligation-dependent probe amplification (MLPA). A total of 140 individuals were diagnosed with epithelial BC. Among them, 72.86% self-identified as Muslim-Thai, while 27.14% were Buddhist-Thai. The majority of cases (60.71%) were diagnosed at or before the age of 50 years. Notably, 20% of the patients presented with triple-negative breast cancer (TNBC). All enrolled patients underwent germline CNV analysis for the BRCA1 and BRCA2 genes. This study represents the first and largest investigation of germline CNVs in the BRCA1 and BRCA2 genes within this population. The absence of germline CNVs in both BRCA1 and BRCA2 suggests that routine screening for such alterations may be unwarranted in this specific population group.