A Significant β-Thalassemia Heterogeneity in the United Arab Emirates

Abstract

The Dubai Thalassemia Center has identified 35 different β-thalassemia mutations in 570 chromosomes from the United Arab Emirates population using gene amplification, hybridization with specific labeled oligonucleotide probes. sequencing of amplified DNA, restriction enzymes, and amplification refractory mutation sysytem techniques. This large number of mutations which represent 21% of the total β-mutations discovered worldwide reflects the heterogenous nature of the population living in tht United Arab Emirates (1). We found that 50% of our β-thalassemia patients have a concomitant a-thalassemia; namely the -α³⁷ kb deletion. Co-inheritance of α-thalassemia especially in the form of two α-globin gene deletions have an ameliorating effect on the phenotype presentation of our β-thalassemia. Nine patients (one homozygote and eight compound heterozygotes) were identified with Hb Monroe (IVS-I,-1 (G → C)), a thalasseniic hemoglobin characterized by an Arg → Thr substitution in codon 30 of the β-globin gene. In addition, one of the patients was a compound heterozygote for Hb Tacoma [IVS-I, +1 (G → C)]; a point mutation affecting the third nucleotide of codon 30 (G → C) causing an Arg → Ser replacement.