THE FREQUENCY OF 14 BETA-THALASSEMIA MUTATIONS IN THE ARAB POPULATIONS

The beta-thalassemias are a heterogeneous group with respect to molecu lar pathogenesis, and different populations and ethnic groups differ w ith respect to the predominating mutations. This variable spectrum of beta-thalassemia mutations has resulted in extensive studies in each p opulation and ethnic group to identify the major mutations. In this st udy we investigated the prevalence of 14 mutations in 253 beta-thalass emia patients drawn from eight Arab countries (i.e. Jordan, Egypt, Syr ia, Lebanon, Yemen, and Saudi Arabia), living in Saudi Arabia and atte nding Ministry of Health hospitals. The mutations investigated include d IVS-I-110 (G-->A), IVS-II-1 (G-->A), IVS-I-5 (G-->C), codon 39 (C--> T), IVS-I-1 (G-->A), frameshift at codons 8/9 (+G), frameshift at codo ns 41/42 (-TTCT), codon 15 (T (G) under bar G-->T (A) under bar G), IV S-I-6 (T-->C), frameshift at codon 16 (-C), IVS-II-745 (C-->G), codon 6 (-A), IVS-I, 3' end (-25 bp), and Cap +1 (A-->C). The most frequentl y encountered mutations were IVS-I-110 and IVS-II-1 which were identif ied in the population of each Arab country. The IVS-I-1 and IVS-II-745 mutations were encountered in Jordanians, Egyptians, and Syrians. The IVS-I-5, codon 39, codon 6, IVS-I, 3' end (-25 bp), and Cap +1 mutati ons were encountered only in Saudis and not in other Arabs, except cod on 39 which was present in the Syrians and Lebanese. Other mutations w ere generally rare and not specific to any Arab ethnic group. This pap er presents preliminary data on the prevalence of 14 mutations in the Arab populations and shows wide variation in the molecular basis of be ta-thalassemia in different Arab ethnic groups. Further detailed studi es to identify the entire spectrum of beta-thalassemia mutations are s tressed.