Chromosome abnormalities in selected newborn infants with malformations in Brazil

Between 1982 and 1985, 109 infants were referred for cytogenetic examination out of a population of 73,192 liveborn infants from eight maternity hospitals surveyed by the ECLAMC/MONITOR program. Thirty-one of the children had a chromosome abnormality different from trisomy 21. Considering the total population surveyed, trisomy 18 was detected in 1:6,099; trisomy 13 was seen in 1:24,397 and unbalanced rearrangements were found in 1:7,319 infants. Those rates were not significantly different from the expected ones, as compared to previous cytogenetic surveys of consecutive births. We concluded that most chromosome abnormalities associated with congenital malformations can be detected at low cost, provided there is a high accuracy of clinical examination and referral criteria, as well as close cooperation between pediatricians and geneticists.