Genetic screening of FFPE breast cancer biopsies for the BRCA1-185delAG mutation in Trinidad and Tobago.

Objective: To investigate whether the quality and quantity of genomic DNA harnessed from existing formalin-fixed paraffin-embedded (FFPE) breast cancer biopsy tissue samples in the public health system of Trinidad and Tobago (T&T) were sufficient for downstream genetic testing and to investigate the occurrence of the common breast cancer susceptibility gene 1 (BRCA1) mutation, BRCA1-185delAG, in these samples.

Methods: Genomic DNA was extracted from 67 FFPE samples using a standard protocol (Qiagen). Samples were genotyped using polymerase chain reaction (PCR) and Sanger sequencing.

Results: The genomic DNA was highly fragmented in the 250-500 bp range. The quality and quantity only allowed testing of one variant. This study successfully genotyped 34 of 67 FFPE breast cancer tissue biopsy samples for the BRCA1-185delAG mutation. This mutation was not detected in the 34 samples.

Conclusion: Existing FFPE cancer tissue biopsies in the public health system in T&T are of limited utility for genetic testing. The absence of the BRCA1-185delAG mutation in the limited number of breast cancer samples tested does not preclude its existence in this population. Further investigations are needed to determine the extent of clinically relevant breast cancer-associated mutations in this population.