Hemoglobins in Togolese newborns: Hb S, Hb C, Hb Bart's, and α-globin gene status

Abstract

The gene frequency of the most important hemoglobin (Hb) abnormalities is reported in a population of 171 Togolese newborns. Hb phenotypes, hematological parameters, and the more frequently described (α-gene deletions were analyzed. Structural abnormalities of β-globin were observed in 35.7% of the children with a gene frequency of 0.105 for β(s) and 0.091 for β(c). The frequency of the different α-globin genotypes was αα/ = 0.71, -α/ = 0.28, and ααα/ = 0.01. All of the individuals homozygous for the -α/genotypes, and most of the heterozygous Individuals, carried Hb Bart's. Within the αα/αα and the -α/αα groups, several individuals with or without Hb Bart's were found; they did not differ from the others by their red blood cell (RBC) parameters but by their levels of fetal hemoglobin (Hb F). The African α2 polymorphism marker, characterized by the replacement of G by TCGGCCC at position 7238 (EMBL HSHBA4, 1993) and of T 7174 by G, was found in 21 newborns. The mean value of Hb F was calculated for each genotype, the mean Gγ percentage was 69.4 ± 4.0%, and the gene frequency of the (AγT)marker was 0.10; this marker was linked to the normal β-globin cluster.