Inbreeding in a South-American newborn series.

Parental consanguinity was investigated in a series of 16, 137 non-malformed newborn infants, ascertained in 64 hospitals, of 27 cities, in seven South-American countries. Parental consanguinity was detected in 135 (0.84%) newborns, giving a mean inbreeding coefficient (a) of 0.00053. The subsamples for five of the seven countries (Brazil, Chile, Ecuador, Uruguay, Venezuela) showed similar consanguinity rates, of about one per cent, an a ranging from 0.00040 to 0.00070, approximately. One country, Argentina, had a three times lower value for both indicators: consanguinity rate: 0.3%, a: 0.00011. Another country, Peru, could not be individually analyzed because of its small sample size. Considering the whole South-American sample, first cousin represented 60% of all consanguineous matings. Significantly more female than male intermediate ancestors were counted in the specified total of consanguineous matings, suggesting a preferential consanguineous mating pattern for urban South-American populations.