THE SPECTRUM OF BETA-THALASSEMIA IN BURMA

The molecular defects causing beta-thalassaemia have been analysed in 85 unrelated Burmese patients. The patients included 14 with homozygous beta-thalassaemia, 70 with HbE/beta-thalassaemia and one with HbS/beta-thalassaemia. Using a combination of allele-specific oligoprobe hybridization and direct sequencing of genomic DNA amplified by the polymerase chain reaction, 95/99 of the beta-thalassaemia alleles have been characterized. Six mutations have been identified of which three, the G-T at IVS-1 position 1, the G-C at IVS-1 position 5 and the deletion of TCTT in codons 41/42, accounted for 85% of the alleles. Despite the diversity of ethnic groups in Burma, the number of beta-thalassaemia alleles in Burma is relatively small. Thus, diagnosis of the majority of the beta-thalassaemias would be possible using a limited number of oligonucleotide probes.