Preimplantation Genetic Diagnosis for β-Thalassemia Using Single-cell DNA Analysis for Codons 17 and 26 of β-globin Gene

BackgroundPreimplantation genetic diagnosis (PGD) of monogenic autosomal hereditary disorders following assisted conception usually involves the removal of one or two blastomeres from preimplantation embryos. However, the amount of DNA from a single blastomere is insufficient to amplify the region of interest. Hence, the whole genome amplification (WGA) method is performed prior to amplifying the genes of interest before analysis of DNA material through polymerase chain reaction (PCR).MethodsIn the present study we report that WGA from a single blastomere extracted from unwanted preimplantation human embryos (obtained from 10 infertile couples) could positively yield microgram quantities of amplified DNA allowing PCR analysis for codons 17 and 26 of the β-globin gene that cause the β-thalassemia disorder. We developed a rapid and highly specific technique of single-cell PCR to amplify a specific region on the β-globin gene for codon 17 (AAG→TAG) and codon 26 (GAG→AAG) by using single-cell PCR.ResultsAbout 249 bp of amplicon for codon 17 and about 200 bp of amplicon for codon 26 were successfully amplified. No mutations were observed. Analyzed embryos were not transferred back to patients because the embryos used as samples were wasted embryos.ConclusionsCompared to other approaches for prenatal diagnosis, PGD is rapid and suitable as a noninvasive clinical tool for identifying genetic disorders for the purpose of reducing selective miscarriages and moral dilemmas. We opine that DNA extraction and amplification can be successfully performed by using single-cell PCR to diagnose genetic diseases before pregnancy.