Background: Breast cancer is worldwide the most common cancer in women and is a major public healthproblem. Genes with high or low penetrance are now clearly implicated in the onset of breast cancer, mostlythe BRCA genes. All women in families at high risk of breast cancer do not develop tumours, even when theycarry the familial mutation, suggesting the existence of genetic and environmental protective factors. Severalstudies have shown that consanguinity is linked to a decreased or an increased risk of breast cancer, but to thebest of our knowledge, there is no study concerning the association between consanguinity and the occurrence oftumours in women with high risk of breast cancer. The objective of this study was to examine whether parentalconsanguinity in families with genetic predisposition to breast cancer affect the risk of siblings for having thiscancer. Materials and
Methods: Over a six-year period, 72 different patients with a histological diagnosis ofbreast or ovarian cancer from 42 families were recruited for genetic counselling to the Department of MedicalGenetics, Rabat. Consanguinity rate was determined in cases and compared to the consanguinity rate in theMoroccan general population.
Results: Consanguinity rates were 9.72% in patients and 15.3% in controls, butthe difference was statistically not significant (p>0.001) and the mean coefficient of consanguinity was lower inbreast cancer patients (0.0034) than in controls (0.0065).
Conclusions: Despite the relatively small sample size ofthe current study, our results suggest that parental consanguinity in Moroccan women might not be associatedwith an altered risk of breast cancer. Large scale studies should be carried out to confirm our results and todevelop public health programs.