Beta-thalassemia in Brazil.

1. Clinical, hematological, genetic and peripheral blood globin synthesis studies were carried out on 17 symptomatic Brazilian thalassemics and their parents who live in the northeast of São Paulo State. The group included 8 beta zero-thalassemia homozygotes, 7 carriers of at least one beta + gene, one delta beta zero/beta zero-thalassemia double heterozygote and one beta zero homozygote also carrying the alpha-chain variant Hb Hasharon (alpha 2(47) His beta 2). 2. The mean non-alpha/alpha ratio for globin biosynthesis of the patients lacking HbA (beta zero homozygotes and delta beta zero/beta zero double heterozygotes) was 0.26 +/- 0.11 (mean +/- SD), which is not statistically different from the value of 0.32 +/- 0.06 obtained for the carriers of at least one beta + gene. In contrast, the mean non-alpha/alpha ratio for the thalassemia major patients (0.22 +/- 0.07) was significantly lower than that obtained for the milder cases (0.34 +/- 0.06) although the beta/alpha ratios for the parents of the two groups were similar. 3. The heterogeneity within this group of Brazilian patients having two thalassemic genes, i.e. 60% who are beta zero homozygotes and 40% who are carriers of at least one beta + gene, is consistent with the Italian origin of most of these patients.