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

BACKGROUND Alpha-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 alpha-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 10 Kb and 4Kb fragments, indicating homozygosity of the alpha-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 alpha-thalassemia-1 SEA type deletion. Homozygosity for alpha-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 alpha-thalassemia-1 SEA type deletion. It can be routinely used for testing couples who both carry the alpha-thalassemia-1 SEA type deletion.