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Alpha thalassemia frequency in newborn children from Porto Alegre, Brazil

Elisete Pedrollo; Mara H. Hutz; F.M. Salzano

Departamento de Genética, Instituto de Biociências, Universidade Federal do Rio Grande do Sul, Caixa Postal 15053, 91501 Porto Alegre, RS, Brasil. Send correspondence to M.H.H.

ABSTRACT

Blood samples from 599 Porto Alegre newborn children were screened by electrophoretic methods. The overall prevalence of Hb Bart's was 3.7%, with a higher (5.4%) frequency among Black, as compared to White (2.5%) babies. Twenty-one children showed Hb Bart's levels between 1 and 4% and one had 5.1% of this hemoglobin. This child had a reduced MCH and MCV, compatible with the thalassemic trait, and was classified as homozygous for a⁺ thalassemia, while the infants with lower levels of Hb Bart's were considered heterozygotes for this condition. Maximum likelihood calculations indicated that this method detects only half of - a/aa individuals. Accordingly, the prevalence of haplotype -a was estimated as 6% in Black and as 2.5% in White children. Red cell counts and other hematological parameters, gestational age, weight and Apgar scores did not differ significantly between normal babies and carriers of Hb Bart's.

Keywords: Alpha thalassemia; Brazil.

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