The alpha-thalassemias are common genetic disorders that arise from reduced synthesis of the alpha globin chains of fetal (alpha2gamma2 HbF) and adult (alpha2beta2, HbA) hemoglobins. The normal human alpha globin gene includes the duplicated alpha genes (alpha2 and alpha1). All diploid cells have four alpha-chain genes (i.e., alphaalpha/alphaalpha). 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 cells from alpha- thalassemia patients. We have demonstrated that deletion of hemoglobin gene alpha1 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 differential PCR. Using this method we have tested hemoglobin alpha gene status from 9 normal subjects and 7 alpha-thalassemia patients. Results clearly demonstrated that different extent of alpha genes deletion in these patients could be differentiated by measuring the band intensity of target genes (alpha1, alpha2) and reference gene (beta-actin) after PCR amplification and gel electrophoresis. We have also been studying on the PCR mediated color complementary assay, which could serve as a quicker, sensitive method to detect gene deletion, omitting gel electrophoresis.
