Does Consanguinity Protect Against Breast Cancer in Tunisian Population?

Abstract

Consanguinity is highly prevalent in many parts of the world. The highest consanguinity rates (20% to 50% of all marriages) occur in North Africa, the Middle East, Southwest Asia and Southern India. The aim of this study is to assess the effect of consanguineous marriages on the incidence of sporadic and familial breast cancer in Tunisia. We ascertained the rate of consanguineous marriage and the average coefficient of inbreeding among 155 Tunisian patients diagnosed with sporadic or familial breast cancer. The coefficient of inbreeding among all breast cancer patients was 0,007. No difference was observed for sporadic (F=0.008) vs familial breast cancer (F=0.007). The coefficient of inbreeding was significantly lower in the breast cancer group than in the Tunisian general population (0.0157). Considering the age of the patients, the level of inbreeding was lower among patients older than 50 (F=0.0027), while those younger than 50 exhibited a coefficient of inbreeding similar to that of the general population (F=0.01). The protective effect of consanguinity against breast cancer, particularly for patients older than 50 years, may be related to the absence of major factors involved in the onset of breast cancer at an early age. This protective effect may be also related to the contribution of recessive alleles of modifier or low-penetrance genes in the homozygous state.