More and more evidence reveals copy number variants(CNVs)have great relevance to common human diseases.For α-thalassemia,there exists a typical relationship between clinical phenotypes and genotypes involving the copy number changes in the human α-globin gene cluster.Except for those high-throughput technologies for screening unknown CNVs in whole genome wide,the assays for targeted CNV genotyping several loci associated with genetic disorders are also amenable.Here we describe a universal quantitative approach,based on nested real-time quantitative PCR(qPCR),for accurate typing copy numbers of the given sites in particular gene locus.In this work we used α-globin gene as a model system,analyzed the reproducibility and sensitivity for different copies of the assay,and then tested 94 samples with 15 different known genotypes.Our results showed that this approach has high sensitivity,and low standard deviations to correctly genotype DNA samples containing different copies of α1 and α2.We demonstrate that our method is rapid,simple,and reliable,could be applied to simultaneously screening for α-thalassemia deletions and triplications.Moreover,it has potential as a versatile technology for the rapid genotyping of known CNVs in the targeted region.