A scientist in China claimed to have created the world’s first gene-edited human beings. How should the U.S. respond?
Soon two American biotechnology firms hope to offer couples undertaking in vitro fertilisation the chance to screen embryos before they are implanted. Pre-implantation genetic diagnosis is already widely used to test for chromosomal abnormalities or specific genetic disorders. But MyOme and Genomic Prediction plan to reconstruct the whole sequence of an embryo’s genome using just a few cells from a biopsy and genetic sequences of both parents. They can then, in theory, calculate the risk the embryo will develop a wide range of different diseases in later life—including ailments that are extraordinarily complicated, involving thousands of genetic variants. By selecting between different embryos, those undergoing IVF can optimise the health of their progeny in a way that those who conceive naturally cannot. That raises ethical concerns. Although both firms will screen embryos for disease risk only, there is no reason why traits such as height or intelligence might not be selected in the same way.
Fertility experts criticise use of optional extras that do not increase chance of pregnancy
Previously reported better fertilization rate after intracytoplasmic single sperm injection (ICSI) than after subzonal insemination of several spermatozoa was confirmed in a controlled comparison of the two procedures in 11 patients. Intracytoplasmic sperm injection was carried out in 150 consecutive treatment cycles of 150 infertile couples, who had failed to have fertilized oocytes after standard in-vitro fertilization (IVF) procedures or who were not accepted for IVF because not enough motile spermatozoa were present in the ejaculate. A single spermatozoon was injected into the ooplasm of 1409 metaphase II oocytes. Only 117 oocytes (8.3%) were damaged by the procedure and 830 oocytes (64.2% of the successfully injected oocytes) had two distinct pronuclei the morning after the injection procedure. The fertilization rate was not influenced by semen characteristics. After 24 h of further in-vitro culture, 71.2% of these oocytes developed into embryos, which were transferred or cryopreserved. Only 15 patients did not have embryos replaced. Three-quarters of the transfers were triple-embryo transfers. High pregnancy rates were noticed since 67 pregnancies were achieved, of which 53 were clinical, i.e. a total and clinical pregnancy rate of 44.7% and 35.3% per started cycle and 49.6% and 39.2% per embryo transfer. A total of 237 supernumerary embryos were cryopreserved in 71 treatment cycles.