heterogenicity of the molecular basis of B- thalassemia among Arabs

ABSTRACT

The molecular basis of beta-thalassaemias [beta-thal] were investigated in Arab populations from different countries. A total of 272 blood samples [5-10 ml] were collected from unrelated beta-thal patients attending the Ministry of Health hospitals in Riyadh, Saudi Arabia, and were grouped according to their nationality into eight groups [ie. Saudis, Jordanians, Egyptians, Syrians, Lebanese, Yemenis, Sudanese and Palestinians]. DNA was prepared from the buffy coat and stored frozen at 70°C until required for analysis. Using Amplification Refractory Mutation System [ARMS], Denaturing Gradient Gel Electrophoresis [DGGE] and dot blot analysis, the following mutations were investigated IVS-1-1, IVS-1-6, CD 15, CD 41/42, CD 8/9, CD 39, IVS 1-5, IVS-II-1, IVS-I-110, Cap+1, IVS-1-3' end [25 bp deletion], CD 6, IVS-II-745, CD 16, IVS-II-654, IVS-I-1 [G-A], CD 17, CD 30, -88 and -28. The results revealed a significant heterogeneity in the molecular basis of beta-thal in Arabs from different countries where each group has a major set of 6-8 mutations accounting for majority [-80%] of the beta-thal. Interestingly IVS-I-110 and IVS-II-1 were found in all Arabs, but at a significantly variable frequency, where they were more frequent in the countries around the Mediterranean and gradually decreased to the East. On the other hand, IVS-1-5, an Asian mutation occurred at a high prevalence in the UAE populations and decreased to the west. Saudi Arabia showed an overlap of both Mediterranean and Asian mutations. The beta-thal gene mutations exhibit considerable heterogeneity in the different Arab populations. These represent either the trend of population movement or new mutations that may have occurred independently. As in the other populations of the world, 5-7 common mutations are characteristic of each country