Patients and Methods
This study was conducted at PH and African Institute of Biomedical Science and Technology (AiBST) laboratory. We included all the patients who met the inclusion criteria into the study. Inclusion criteria were; women aged 18 years and above with histologically proven breast cancer diagnosis, willingness to participate in the study and attend study follow-up visits as well as have been prescribed doxorubicin based chemotherapy but not received the first. The exclusion criteria were; non-black women, prior treatment with any chemotherapy and patients with prior chest wall radiotherapy. Five milliliter of whole blood was collected from each patient who met the inclusion criteria by venipuncture at entry and stored at the Zimbabwe repository. Two hundred microliters of the whole blood was used to extract DNA using Kingfisher flex Magnetic Particle Processor. Genomic DNA was extracted using the Applied Biosytems MagMAX DNA Multi-Sample Ultra 2.0 Kit using an automated system (King FisherFlex Magnetic Particle Processor System). The extracted DNA was quantified using Qubit, dsDNA BR (broad range) Assay Kit and run on the Invitrogen Qubit 4 Fluorometer according to the manufacturer’s protocols. Fifty ng/µl was the recommended amount of DNA for genotyping by manufacturer hence nuclease free water was used to normalize the DNA to this recommended concentration. The extracted DNA was stored at either -20°C short term or -80°C long term before analysis. Written informed consent was obtained from all patients or legal guardians. The study was approved by the ethics committees of PH.