Prenatal diagnosis of Alpha-thalassemia of Southeast Asian deletion with non-radioactive southern hybridization

Background: α-thalassemia is a common hereditary disease in Taiwan. Affected patients always carry a heavy burden of morbidity and early death. Prenatal diagnosis has reduced the disease burden on families and the health care system. This study evaluated a new non-radioactive Southern blotting hybridization method for prenatal diagnosis of this disease. Methods: Seventy two chorionic villi samples (CVS) and 30 amniocyte samples from 102 pregnancies of couples who were both heterozygous for α-thalassemia-1 of the Southeast Asian (SEA) type deletion were studied. A non-radioactive Southern blotting hybridization method using a dig-alkaline phosphate detection system was developed for use in this study. Results: Non-radioactive Southern blotting hybridization data showed that 19 (26%) CVS and five (17%) amniotic fluid samples had 10Kb and 4Kb fragments, indicating homozygosity of the α-thalassemia-1 SEA type deletion. DNA samples were extracted from most of the aborted tissue of the 24 fetuses with a diagnosis of homozygous for the α-thalassemia-1 SEA type deletion. Homozygosity for α-thalassemia-1 SEA type deletion was reconfirmed by Southern blotting hybridization in all of these samples. Conclusions: The non-radioactive Southern hybridization protocol used in this study allows efficient and accurate early prenatal diagnosis of α-thalassemia-1 SEA type deletion. It can be routinely used for testing couples who both carry the α-thalassemia-1 SEA type deletion.