HB O-Arab [β121(GH4)GLU→LYS]: Association with DNA Polymorphisms of African Ancestry in two Mediterranean Families

Hb O-Arab [β 121(GH4)Glu→Lys] was detected in two Mediterranean families, one from Southern Italy and the other from Albania. The GAA→AAA mutation at codon 121 was characterized by DNA sequencing. The mutant genes were associated with the same β-globin gene framework variant and with the rare Hpa 1/3′β polymorphic restriction site generating a 7.0 kb fragment. However, at 5′ the gene of the Italian family was associated with the restriction fragment length polymorphism subhaplotype [+-+] and the Taq I/3′Gγ polymorphic site, while that of the Albanian family was associated with subhaplotype [--+] but not with the Taq I/3′Gγ site. The particular features of these polymorphisms support the hypothesis of an African origin for the Hb 0-Arab gene and a subsequent recombination event leading to the haplotype found in the Italian family.