MOLECULAR STUDIES ON THE DIST RIBUTION OF β - THALASSEMIA IN IRAN: THE BASIS FOR PRENATAL DIAGNOSIS

By application of modern recombinant DNA technology, especially the polymerase chain reaction (PCR)/dot-blot hybridization techniques, we have investigated the molecular basis of β-thalassemia from four different regions of Iran: central, south-east, south and north. In this study, the DNA samples were isolated from patients and for the identification of the mutations, the 6 oligonucleotide probes for the mutations of IVS.1/nt. 110, .lVS.1/nt.6, IVS.1/nt.1 , nonsense codon 39, frameshift codon 8 and IVS. 2/nt.1 were selected with respect to their relative frequency in the neighbouring country, Turkey. Four mutations accounted for76.2% and of these, the most frequent was the nonsense codon 39 mutation, which accounts for 60.3% of the β-thalassemia alleles tested. The remainder, in decreasing order of frequency, wereframeshift codon 8(9.5%), lVS. 1/nt.6 (4.8%) and IVS.1/nt.11O(1.6%). No hybridization was observed with the probes corresponding to the mutations of rvS.I/nt I (0/ A) and rvS.2/nt.1 (0/ A). These results also revealed that the distributions of different types of mutations were different in the four regions. This information and the introduction to the methodology used in this study will facilitate the prenatal diagnosis of the disease in Iran.