[Molecular screening and prenatal diagnosis of the deletional alpha-thalassemia by polymerase chain reaction amplification].

For the genetic counselling, 8,432 blood samples from Chinese couples were screened for detecting alpha-thalassemia in Guangzhou city. The positive diagnosis of 646 (7.66%) alpha-thalassemia patients was made. One hundred DNA random samples from the above positive cases were collected and were analysed by using polymerase chain reaction (PCR) to determine the genotype of alpha-thalassemia of Southeast Asian deletion(--SEA/). Of 100 alpha-thalassemia individuals screened for the (--SEA/) mutation, 99 (96 with alpha-thalassemia trait and 3 with hemoglobin H disease) were detected by the present method. This mutation was not found in the remaining one with alpha-thalassemia compound Hb Q. We also used this assay to analyse DNA samples from cord blood in 6 pregnancies at risk of Bart's hydrops fetalis, in 1 at risk of Hb H disease for prenatal diagnosis.