Haplotypes and levels of fetal hemoglobin and ^Gγ to ^Aγ ratios in mediterranean patients with thalassemia minor and major

This study concerned the γ chain composition of Hb F and the haplotypes of 44 patients with β‐thalassemia major or intermedia and many of their relatives. Seventeen patients came from Northern (Turkish) Cyprus, 12 from the Istanbul area, and 15 from Macedonia and Bulgaria. Analysis of the ^Aγ^T‐^Gγ‐^Aγ^I ratio was made by HPLC, while haplotyping involved seven restriction sites. Specific haplotypes were present in certain populations; haplotype I [1] is the dominant type among North Cypriot thalassemia patients. Numerous types were seen in the patients from the Balkan countries. A direct relationship between the ^Aγ to ^Gγ ratios and the haplotypes, which exists among black β‐thalassemia heterozygotes [3], was also observed among these Mediterranean patients, although such analyses were considerably complicated by extensive blood transfusion therapy. Haplotypes without the Hinc II restriction site within the Ψβ gene were associated with lower ^Gγ values than those that had this polymorphic site. The ^Aγ^T chain was observed in a small number of β‐thalassemia homozygotes and heterozygotes. Three thalassemia chromosomes with slightly different haplotypes and one normal chromosome with a related haplotype were associated with the γ 75 Ile→Thr substitution. A few patients with a thalassemia intermedia were heterozygotes for β‐thalassemia with either haplotypes V or VII [1] while the “nonthalassemic” chromosome had a haplotype I, which is the most common “ β‐thalassemic” haplotype among the Mediterranean population(s). Detailed analyses of this chromosome have not been completed.