Abstract

Background: Most pathological lesions of the breast present as a tumour or tumours. The majority of these lesions are due to genetic mutations from environmental and lifestyle factors. Kirsten rat sarcoma viral oncogene homolog (KRAS) gene and Retinoblastoma (Rb) gene play vital roles in the control of the cell cycle and cell proliferation.


Materials and Methods: A total of 20 formalin fixed paraffin embedded blocks, consisting of benign fibroadenoma (FA) (10) and malignant invasive ductal adenocarcinoma (IDC) (10) breast specimen were retrieved from the Pathological Archives for this case-control, retrospective study. Small portions of tissue were cut from the tissue blocks and ground in a sterile mortar and pestle with 500µl of extraction buffer for deoxyribonucleic acid (DNA) extraction and polymerase chain reaction (PCR) amplification, purification and sequencing. Ethical approval was obtained from the Ethics committee of the Federal Teaching Hospital.


Results: In Rb gene single nucleotide polymorphism (SNP) mutation frequency, there was 100% transition mutation in Fibroadenoma (FA) and 79% transition, 16% transversion and 5% indel mutation in IDC. In Rb gene functional mutation frequency, there was 100% missense mutation in FA, and 72% missense, 28% silent and 0% nonsense mutation in IDC. In KRAS gene SNP mutation frequency, there was 71% transition, 21% transversion, and 8% indel mutation in IDC. KRAS gene functional mutation, there was 86% missense, 14% silent and 0% nonsense mutation in IDC.


Conclusion: The majority of mutations arise as a missense class. This demonstrates that missense mutations possibly play a significant role in breast cancer aetiology. There is a paucity of data on the mutation of Rb and KRAS genes on FAs and IDC in this part of the world hence the need for the present study.


Keywords: Mutation, Retinoblastoma, KRAS, Fibroadenoma, Invasive Adenocarcinoma, Breast Cancer