Background: An estimated 600 million people in the world have consanguineousparents. The effect of consanguinity on the risk of breast cancer is uncertain. The objective of thiscase-control study was to examine whether parental consanguinity and different levels of inbreeding affectthe risk and pathology characteristics of breast cancer. Material/Methods: Over a 36-month period, consecutivefemale breast cancer patients were recruited in the main cancer hospital in the United Arab Emirates.All were locally born Arabs with a tissue diagnosis of breast cancer. The controls were locally bornArabs without breast cancer matched to cases by sex, age, and residence. The coefficient of inbreeding(F) of both groups was determined from information they provided about their parents' kinship. Results:The mean age of the 72 patients and 187 controls was 48.6 years (range: 25-86) and 48.5 years (range:25-82), respectively (P=0.46). Consanguinity rates of the patients and controls were 29.2% and 28.9%(P=0.96) and the coefficients of inbreeding were 0.0117 and 0.0167 (P=0.21), respectively. More closelyinbred women (F>/=0.0625) were less frequent among patients than controls, but the difference was notstatistically significant (P=0.12). The rates of pathological stage of disease, tumor histologies, andtumor grades were similar between more and less inbred patients. Conclusions: Parental consanguinityin Arabs, even when a marriage is between first cousins or double first cousins, was not associated withan altered risk of breast cancer.

Keywords: Aged, 80 and over, Breast Neoplasms - genetics, Case-Control Studies, Consanguinity, Prospective Studies, Risk Factors, United Arab Emirates