Correlation of Clinical and Pathological Parameters with the Diversity and Genetic Evolution of Breast Cancer in Senegalese Women.

ABSTRACT

Aims: The purpose of this study was to assess the hypothesis that genetic diversity of breast cancer is related to clinical and pathological tumors characteristics. Study Design: Representative sequences of mitochondrial Cytochrome b gene of cancerous tissues were analyzed to determinate diversity and genetic evolution of breast tumors in Senegalese women. Place and Duration of Study Department of biology Animal (University Cheikh Anta Diop), laboratory of molecular biology (IRD-CBGP), 2011-2013. Methodology: Genetic diversity of breast tumors in 57 Senegalese patients was estimated by analyzing sequences of the Cytochrome b mitochondrial coding gene. The Cytochrome b sequences from cancerous tissues were aligned using BioEdit version 7.0.8. Number of polymorphic sites, parsimony informative sites, the rate of transitions/transversions and the nucleotide frequency were calculated using MEGA 5.05. Genetic distance (d) was calculated with MEGA 5 using the Kimura 2-parameter (K2P) model. The index of genetic differentiation (Fst) used to describe the distribution of the genetic diversity between sub-groups was calculated with the software DnaSP version 10.5.01. The significance level (P-value) was 0.05. Results: Analyses have revealed a high score of haplotype (Hd=0.991+/-0.008) and nucleotide diversity (Pi=0.15650+/-0.01326). Statistical correlations have shown a positive association between the risk factors (age of the patients, appearance of the first menstruation beyond 12 years, number of gestation) and nucleotide diversity of tumors (P<0.0001). Statistical analyses based on t-test showed a positive association between age, date of onset of the first menstruation and nucleotide diversity (Pi), between healthy and cancerous tissues for each patient (P<0.0001). Conclusion: Our results have shown an important genetic diversity in breast tumors. A strong genetic differentiation was noted depending on the number of gestations.