Real-time quantitative PCR analysis for alpha-thalassemia-1 of Southeast Asian type deletion in Taiwan

Since homozygosity of the alpha -thalassemia-1 of Southeast Asian (SEA) typ e deletion results in hydrops fetalis, a novel protocol based on the real-t ime quantitating polymerase chain reaction (PCR) technique has been develop ed to quantify the intact and aberrant alpha -globin genes in adults. The r atio of the normal/SEA-bearing alpha -globin genes was expressed in cycle t hreshold (C-T) values. Theoretically, a relative ratio of one to one was an ticipated in individuals carrying the SEA type deletion. Twenty-five hetero zygous and 20 normal cases were analyzed retrospectively with this protocol . Data showed that the C, values for the intact alpha -globin gone allele a nd the allele bearing the SEA type deletion in carriers were 28.74 +/- 1.49 and 26.46 +/- 2.05, respectively. Therefore, the ratio of normal/SEA type deletion-bearing a-globin genes in the carriers was 1.09 +/- 0.043. No ambi guous results were observed from other less common genotypes associated wit h alpha -thalassemia, such as the Philippine type deletion. Based on the re sults, we concluded that this protocol could provide a rapid method to mass screen carriers with alpha -thalassemia-1 of SEA type deletion in this reg ion.