Rapid Identification of the &Szlig;-Thalassemia Mutations by Applying Cel I Nuclease Mutation Detection System and Capillary Electrophoresis

Background: Beta-thalassemia is a common autosomal recessive hereditary disease in the Meditertanean, Asia and Africa area. It is a single gene inheritable disease resulting from one or more of a total of more than 200 different mutations in the beta-globin gene (HBB). For the clinical practice, the detection of beta-globin mutations were mainly depends on polymerase chain reaction-restriction fragment length polymorphism (PCR- RFLP) and direct sequence technique. A more sensitive, efficient and reliable mutation-screening method is warrant and essential in order to establish appropriate prevention programs for at-risk populations based upon a molecular diagnosis. Methods: To further enhance the detection efficiency and accuracy, the purpose of this study is to develop a novel genotyping method for common mutations in beta-globin gene. We have developed a rapid and highly-specific mutation screening test for the diagnosis of beta-thalassemia by CEL I nuclease mutation analysis based on the denaturing high performance liquid chromatography (DHPLC) system and ABI PRISM 310 Genetic Analyzer. To illustrate the efficacy of this approach, the exons of the beta-globin gene were amplified by PCR using primers 5'-labeled with fluorescent dyes of two colors. This study will demonstrate the usefulness of CEL I Nuclease as a method to genotype mutations in beta-globin gene for applying in daily clinical practice. Results: Assays conditions were established based on the analysis of 50 DNA samples from heterozygotes or compound heterozygotes for the mutations in beta-globin gene. Homozygous wild-type DNA samples produced electropherograms containing only single peak, whereas samples heterozygous for a specific mutation displayed two peaks for that mutation site. In the double- blind validation analysis, all 50 DNA samples were showed 100% assay specificity. Conclusions: Compared to classic approaches of mutation screening, when coupling with the previous established heteroduplex and primer-extension analysis, this method allows a rapid, highly sensitive, cost effective and semi-automated mutational screening of a large number of samples. Therefore, mutational analysis by CEL I Nuclease Mutation Detection System will be helpful as the first-line clinical screening and diagnosis tool of beta -thalassemia