Preimplantation diagnosis of alpha-thalassemia by blastomere aspiration and polymerase chain reaction: preliminary experience.
The ability to diagnose and detect the presence of debilitating and life-threatening diseases would be an invaluable asset to those involved in in vitro fertilization programs. To investigate the possibility of diagnosing severe alpha-thalassemia before implantation, DNA sequences targeting the abnormal deletion breakpoint and the normal region of the alpha-globin gene were amplified by polymerase chain reaction from blastomeres aspirated from human preimplantation embryos. Before performing this experiment, a mouse model blastomere aspiration technique was examined to confirm embryo survival and normal development capability. The mouse embryos showed undisturbed development in the five- to seven-, as well as the eight-cell stages when one, or two (eight-cell stage only) blastomeres were aspirated. The four-cell embryos had a lower survival rate but had a blastocyst formation rate comparable to the more advanced stages and the control embryos. In the human embryo experiment, no homozygous Southeast Asian alpha-thalassemia was detected in the aspirated blastomeres, although two heterozygotic alpha-thalassemia embryos were discovered. The sensitivities of targeting sequence detection in the mouse and human blastomeres were between 50% and 76% in the respective groups. This study supports the feasibility of preimplantation diagnosis of severe alpha-thalassemia when both father and mother are carriers of this inheritable disease.