In an effort to prevent passing on genetic disorders into the next generation, genetic technologies are gaining more acceptance in China and other places to give parents a say in their offspring’s characteristics. While we’re still far from doing human gene-editing experiments to make “designer babies”, parents can avail now of services to identify in advance if a not-yet-born baby has inherited their genetic faults and then decide his or her fate. One technique is preimplantation genetic diagnosis (PGD).
Scientists use PGD to identify in vitro fertilized embryos and select ones which do not carry genetic defects of the parents. When embryos are a few days old, cells are taken and tested. An unaffected embryo is then deemed a good candidate for implantation into the uterus; others who passed are frozen as back-ups while the affected ones are discarded. Apart from preventing inheritance of genetic disorders, the technique can also aid women who have problems with pregnancy (advanced age, recurring pregnancy loss or multiple fertility treatment failures).
Embryo biopsy was first done on rabbit embryos in 1968. By the 1980s, PGD was developed in the UK as an alternative to prenatal diagnosis. PGD’s original aim at the time was to determine gender in order to avoid the proliferation of an X-linked disorder (this is a sex-linked condition that is passed from a mother to a child due to an abnormal X-chromosome). The first successful PGD case was reported in 1988; as of 2006, the number has grown to 15,000.
China was relatively late in using PGD due to initial issues of potential abuse and embryo’s safety. As the one-child policy was relaxed in 2013 and a robust reproductive medicine program was enacted, centers who offer PGD grew from four in 2004 to 40 in 2016. China’s pace of adoption is so big it overtook the US in the number of conducted procedures. In 2015, China reported its first “cancer-free baby” who was conceived with PGD’s aid.
One of the benefits of PGD is that parents can avoid termination of pregnancy. When prenatal diagnostic procedures are performed to check genetic problems of a fetus aged 10-16 weeks, parents sometimes have to choose termination of pregnancy if results are not good. PGD eliminates that difficulty of choice as detection is done at an earlier stage.
PGD is currently available for identifying most genetic conditions. Some of these are hemophilia, color blindness, most neuromuscular diseases, cystic fibrosis, sickle cell anemia, Huntington’s disease, Down’s syndrome, brittle-bone disease and deafness. The economic aspect of preventing a genetic disease is also worth emphasizing; for instance, the cost of PGD for avoiding cystic fibrosis is $57,500 as compared to lifetime treatment that could amount to $2.3 million. In the future, PGD may also cover common diseases like diabetes, hypertension and cancers.
While PGD is exciting and revolutionary, it remains controversial and limited for some reasons. For the Catholic Church and pro-life advocates, life begins at conception and discarding a defective or excess embryo is equivalent to ending a life. Despite the covered conditions, the technique is still not 100% reliable against defects in an already implanted embryo, thus, still requiring monitoring during pregnancy. The embryo’s safety is also being questioned whenever a cell is removed for testing. Moreover, PGD may also result to false results as that one cell may not be representative of the embryo source.
While countries have regulations in place, there are also potential abuses with PDG. UK limits application to 400 conditions but US clinics have more room to operate. Sex selection is controversial in the US but the ethics committee of the American Society for Reproductive Medicine allows clinics to do what is permissible. PGD can also be used to screen genetic issues that are not necessarily medical in nature, like intelligence or physical appearance. Another aspect of PGD is having parents choose not to end the passing on of their genetic disorders. In fact, there was one case in the US where parents purposely chose an embryo with hereditary deafness to preserve deaf culture.
“There are ethical problems, but if you bring an end to the disease, I think it’s good for society,” says Qiao Jie, president of Peking University Third Hospital and a fertility specialist. Still, as the knowledge grows and the benefits increase, PGD and other “playing God” techniques will continue to generate controversies and moral concerns in society.