The alpha-thalassemias are common genetic disorders that arise from reduced synthesis of the alpha-globin chains of fetal and adult hemoglobins. The normal human alpha-globin gene includes the duplicated alpha-genes 1 and 2. All diploid cells have four alpha-chain genes. In alpha-thalassemia syndromes, alpha-globin synthesis is either diminished or absent due to either deletional or non-deletional abnormalities involving the alpha-globin genes. At present, for a variety of technical, logistic and economic reasons, large-scale carrier screening and appropriate ante-natal detection programs have not been established for the populations in which this syndrome occurs. Here, in our pilot studies, we have successfully established a simple, rapid, sensitive PCR assay for detecting alpha-gene deletion using DNA from fresh blood cell from alpha- thalassemia patients. We have demonstrated that deletion of hemoglobin gene alphal or alpha2 could be determined using three sets of primers (two sets for alpha1 and alpha2 gene respectively and one set for beta-actin as internal control) from alpha-thalassemia syndrome patients by the differential PCR. Using this method we have tested hemoglobin alpha genes status from 21 normal subjects and 66 alpha-thalassemia patients. Results clearly demonstrated that different extents of alpha-genes deletion in these patients could be differentiated by measuring the band intensity of the target genes and reference gene after PCR amplification and gel electrophoresis. We have also been studying the PCR mediated color complementary assay, which could serve as a quick, sensitive method to detect alpha-gene deletions omitting gel electrophoresis.
