Molecular basis of B-thalassaemia in Italy

The β-thalassaemias are a heterogeneous group of inherited disorders of haemoglobin synthesis, all characterized by the absence (β°) or reduced output (b+ or b++) of the β chains of haemoglobin. Over 200 different mutations have been identified in the β-globin gene of patients with β-thalassaemia, whose relative frequency is different in various countries. With the exception of a few deletions, the bulk of them consist of point mutations or the loss of one or two bases, wich interferes with gene function either at the transcriptional, translational or post-translational levels. The aim of this study was to identify the frequency of β-thalassaemia mutations in Italy by molecular analysis of 1.207 β-thalassaemic alleles. Twenty-one different mutations have been identified. Three of them accounted for over 70% of the β-thalassaemia alleles identified in this population sample (codon 39, IVS1-6, IVS1-110). Thirty-six different genotypes among thalassaemia intermedia and 18 among thalassaemia major have been recorded, being some genotypes restricted to thalassaemia intermedia including homozygosity for IVS1-6 T → C and compound heterozygosity for a promoter mutation (-87 C→G ) or -101 C→T).