Genetic effects in Brazilian populations due to consanguineous marriages.

Estimates of "relative risks" and "attributable risks" are presented for two Brazilian regions with the lowest (F = 0.00030) and the highest (F = 0.00395) inbreeding levels of the country, and for the whole country (F = 0.00088). The abolition of all consanguineous marriages (from second cousins up to and including uncle-niece/aunt-nephew marriages) in Brazil would eliminate only about 0.22, 3.05, and 0.65% of the "total damage," respectively. "Total damage" is defined as including abortions, miscarriages, stillbirths, infant-juvenile mortality (up to the age of 20 years), and anomalies in the survivors. The reduction of prenatal damage would be 0.11, 1.46, and 0.31%, and that of postnatal damage would be 0.49, 6.65, and 1.36%, respectively.