Biochemical and Molecular Aspects of β-Thalassemia Types in Northern Sardinia

Abstract

Forty-three patients with β-thalassemia from Northern Sardinia (31 severe and polytransfused, six follow-up babies, five adults with mild thalassemia who were not transfusion dependent, and a young transfused patient was also affected by a disease of intermediate severity) were studied in order to establish the fetal hemoglobin composition, restriction fragment 1ength polymorphisin haplotypes at the β-globin gene cluster, and the type(s) of mutation. Haplotype II was prevalent, [56/86 chromosomes (65%)], haplotype I was also fairly common, [22/86 chromosomes (25%)], while other types were relatively rare. The nonsense mutation at codon 39 was nearly exclusive, [76/80 chromosomes (95%)]. Other β-thalassemia mutations occurred on chromosomes with haplotypes 111, IX, X, and perhaps V, and a new type related to II. The mutated A_γT gene was associated with type type II, X, and the new type. Type IX was linked to a βd` gene and to an Xmn I site 5′ to the G<sub>γ</sub> gene, to a high G<sub>γ</sub> globin level, and to a disease of mild severity. Type I11 was associated with a β<sup>+</sup>+-thalassemic gene. The d`39 mutation linked to type I1 was associated with thalassemia intermedia in three patients.