α-Globin gene deletions associated with α^Aand α^{G Philadelphia}genes in an Algerian family that includes two Hb G homozygotes

Summary

An Algerian family with a high degree of consanguinity and including two homozygotes for Hb-G Philadelphia is presented. Whether homozygotes or heterozygotes, all subjects displayed microcytosis (with various degrees of poikilocytosis) and a moderately depressed α-globin chain synthesis. Hb H and Heinz bodies were absent. DNA mapping revealed the presence of 3.7 kb deletion resulting from the rightward type of recombination event between α₂ and α₁ genes on both the α^A/and the α^G chromosomes. Such data indicate that the −α^A/ and −α^G/ haplotypes are involved and suggest that the −α^G/ haplotype, which is very rare in Algeria, has an African Black origin. In subjects with genotype (−α^A/−α^G/) or (−α^G/−α^G/), the output of the remaining α genes is sufficiently high to avoid the appearance of Hb H. This situation contrasts with that reported in an Algerian patient, who had a (−α^A/−α^A/) genotype but who was producing Hb H (Whitelaw et al. 1980). The data collected from this family suggest that the −α^A/ haplotypes are heterogeneous in Algerians.