Genetic testing is a rapidly developing field offering the possibility of screening for specific genetic conditions. Recent breakthroughs in embryo screening technology have enabled researchers to go a step further. Now, there is a very real possibility of being able to screen for specific character traits as well as a wide range of less predictable diseases.
Simple genetic tests designed to assess embryos during the IVF process have been used for many years.This allows parents to assess the risk of passing on single gene conditions, like Tay Sachs disease, or to identify conditions caused by chromosomal abnormalities, such as Down Syndrome.
The idea of combining IVF and genetic testing to decrease the possibility of any disease is appealing--but the success of the most rigorous testing measures is debatable.
Most medical conditions, assessed through the new method of screening for polygenic traits, are influenced by hundreds of genes. While geneticists maintain that it’s possible to calculate a polygenic risk score for diseases like heart disease, the reliability of these tests remains questionable. Some wonder if an emphasis on genetics makes sense.
Polygenic testing raises the possibility of predicting complicated diseases like heart disease while ignoring the many other factors involved. Postnatal factors such as exercise, eating habits, and other lifestyle decisions contribute heavily to heart disease but can’t be predicted through genetic testing.
Those in the field of reproductive medicine must grapple with the reality of tests that could reveal the slight possibility of disease or disability. Should patients be allowed to select embryos in at-risk categories for polygenic diseases? For many, the decision to forgo the use of embryos in at-risk categories might not be possible. It could become a choice between an embryo in an at-risk category or no embryo at all.
While many consider polygenic risk scores useful for prospective parents regardless of their accuracy, tests purporting to measure IQ remain controversial. Calculating the reliability of genetic testing for intelligence or height is difficult. Detailed models analyzing genetic data from 1000 participants revealed that those with the highest height did not have the highest polygenic scores for height. This suggests that there is an element of uncertainty surrounding genetic tests that remains unresolved.
In addition to the difficulty of conducting these tests effectively, the effects of many genes identified as playing a role in intelligence remain unknown. There are also moral and ethical implications of genetic discrimination resulting from predictive testing.
Some data analysis suggests that the possibility of controlling for characteristics and physical traits is extremely limited. But in a future where careful selection of traits is more accessible, how will we deal with ethical dilemmas surrounding the selection process?
Although rigorous genetic screening appears to promise a solution to heart disease, depression, and more, the reliability of these tests remains questionable. So, too, should we question the ethical ramifications of allowing geneticists to screen for traits such as intelligence or height.
Main image courtesy of CDC.