Successful preimplantation genetic diagnosis for alpha- and beta-thalassemia in China

In southern China, the average carrier rates of alpha-thalassemia and beta-thalassemia in the population are as high as 10.3% and 2.8%, respectively. Because of the high rates, they are known as 'social diseases' in some regions. In this study, the fluorescent gap PCR, which can detect the alpha-thalassemia Southeast Asia deletion (SEA deletion), was applied in four clinical applications of preimplantation genetic diagnosis (PGD) on four couples, among whom both partners were alpha-thalassemia carriers. Two patients became pregnant and two healthy babies were born, which confirmed the PGD results. The single cell multiplex nested PCR followed by reverse dot blot (RDB), which can simultaneously detect the 16 beta-thalassemia mutations in the Chinese population, was applied in four clinical PGD cycles on four couples among whom both partners were beta-thalassemia carriers. One pregnancy was achieved and it resulted in a live healthy birth, which confirmed the results of PGD. The amplification efficiencies of the two protocols described above were 89.5% and 93.9%, respectively. The allele drop-out (ADO) rates of these two protocols were 5.9% and 10.9%, respectively.

These studies represent the successful applications of PGD protocols that can detect more than 95% of alpha- and beta -thalassemia mutations in the Chinese population.