Prenatal diagnosis of hemoglobinopathies by pyrosequencing: a more sensitive and rapid approach to fetal genotyping

Prenatal diagnosis of the hemoglobinopathies by fetal DNA analysis is currently performed in most countries, either by DNA sequencing, restriction enzyme polymerase chain reaction (RE-PCR) or the amplification refractory mutation system (ARMS). These methods are time consuming and prolong the turnaround time for diagnosis. We here describe a method utilizing pyrosequencing for the prenatal diagnosis of 12 common nondeletional α- and β-globin gene mutations in the UK population. In particular, it replaced the diagnosis of sickle cell disease by RE-PCR and for the diagnosis of β-thalassemia (β-thal) by Sanger DNA sequencing. We have genotyped 148 chorionic villi and 29 uncultured amniotic fluid DNA samples by pyrosequencing and found 100% concordance with the fetal diagnosis result obtained by ARMS-PCR or DNA sequencing. Pyrosequencing was more robust, revealing an 83% decrease in diagnostic failures using uncultured amniocyte DNA samples, and also quantitative, revealing one case of allelic imbalance due to maternal DNA contamination. Overall, we found pyrosequencing to be simpler, more robust, quicker, and less expensive than conventional sequencing and RE-PCR, making it a good choice for rapid and cost-effective prenatal diagnosis of thalassemia and sickle cell disease.