Molecular diagnostics of the HBB gene in an Omani cohort using bench-top DNA Ion Torrent PGM technology

Hemoglobinopathies, such as sickle cell disease (SCD) and beta-thalassemia major (TM), are severe diseases and the most common autosomal recessive condition worldwide and in particular in Oman. Early screening and diagnosis of carriers are the key for primary prevention. Once a country-wide population screening program is mandated by law, a sequencing technology that can rapidly confirm or identify disease-causing mutations for a large number of patients in a short period of time will be necessary. While Sanger sequencing is the standard protocol for molecular diagnosis, next generation sequencing starts to become available to reference laboratories. Using the Ion Torrent PGM sequencer, we have analyzed a cohort of 297 unrelated Omani cases and reliably identified mutations in the beta-globin (HBB) gene. Our model study has shown that Ion Torrent PGM can rapidly sequence such a small gene in a large number of samples using a barcoded uni-directional or bi-directional sequence methodology, reducing cost, workload and providing accurate diagnosis. Based on our results we believe that the Ion Torrent PGM sequencing platform, able to analyze hundreds of patients simultaneously for a single disease gene can be a valid molecular screening alternative to ABI sequencing in the diagnosis of hemoglobinopathies and other genetic disorders in the near future.