[Alpha thalassemia in Macedonia].

Abstract

The frequency of alpha thalassemia in SR Macedonia was determined with studies of Hb Bart's in 1.140 newborn babies. Hb Bart's was found in 83 infants. Distribution of the levels of Hb Bart's in these neonates, as determined by column chromatography on CM Sephadex, was trimodal. The mean values for Hb Bart's in the three groups were 0.5% (SD = 0.22), 1.61% (SD = 0.48), and 4.88% (SD = 0.81). The first group is believed to result from asynchronism of the neonatal "switch off" of gamma chains and activation of beta chain production. The second and the third group represent alpha thal2 and alpha thal1, respectively. Thus, the incidence of beta thal2 in SR Macedonia is 2.4%, and that of alpha thal1 0.8%. Hb H disease was found in three out of 16.000 school children. This form of alpha thalassemia was also found in five out of 2.800 patients examined for the course of anemia. Biosynthetic studies of family members of the eight individuals with Hb H disease showed that one parent is heterozygous alpha thal1 while the other is heterozygous alpha thal2. All individuals with alpha thalassemia had a reduced rate of synthesis of the alpha chains. The mean alpha/beta total activity ratio in individuals with Hb H disease was 0.51 (+/- 0.08), in heterozygous alpha thal1 0.74 (+/- 0.06), and in heterozygous alpha thal2 0.86 (+/- 0.06). Experiments with in vitro translation of globin mRNK isolated from patients with Hb H disease showed lower alpha/beta ratios (0.06) than the intact cell ratios. These results support previously published data that in Hb H disease and alpha thalassemia trait, there is quantitative deficit in alpha globin mRNK, which is a consequence of deleted alpha globin genes.