The Promise of Genetic Testing?
Genetic testing is complicated. No really, it is! Since the concepts of genetics and genetic testing are so abstract for most people, coupled with hearing about all of these new and fancy genetic technologies, people assume a simple genetic test can tell you just about anything. Unfortunately, it can’t. Here are a few things about genetic testing which will hopefully set you straight.
1) We cannot prenatally test for intelligence, height, hair color, or athletic ability. We cannot create designer babies either. This comes up a lot when we think about the ethics of prenatal testing and the fear of eugenics. We can’t test for, or manipulate these traits because we don’t know the gene, genes, combination of both genes and environmental factors which contribute to their development.
2) Prenatal testing at this point is limited to things which are common, or known. We can test your unborn baby for Down syndrome (caused by 3 copies of chromosome 21), or other chromosome abnormalities. However no matter how much testing we do, we cannot test for mental retardation, autism, or even rule out the possibility of any genetic diseases or problem. This is primarily because, as I mentioned before, we don’t know the cause or causes of these things. If there is a specific genetic disease in your family where the gene and mutation has already been identified, we CAN test your baby for that. However when it comes to prenatal genetic testing, we are limited to only being able to test for things when we know EXACTLY which gene we’re looking for, and many times, what specific mutations we’re looking for within the gene.
3) While we can sequence your genome, we can’t really tell you what it all means, yet. As perhaps you have been starting to see, for all that we do know about genetics, we still don’t know a TON. Genetics, and the interplay of our genes and environment are much more complex than you might expect. And in addition to the genes which we know of in the body, there is a large amount of regulatory regions which affect how those genes are expressed. Even the environment can affect how our genes are expressed. Without fully understanding the interplay between our genes, the regulatory regions of our DNA, and our environment, we can’t fully understand and explain the full implications of the genetic “sequence.”
4) Genetic testing does not consist of one “catch all” genetic test. There is no one genetic test which can tell you everything you’ve ever wanted to know about your future health risks, medical issues for your kids, and if you’ll develop cancer in the future. When we do genetic testing, we test usually one specific gene, sometimes even a panel of genes, based on the particular symptoms or family history. That’s why the process of genetic counseling and genetic testing is so thorough. We assess your medical and family history to determine which genetic test should be ordered, since after all, you do have thousands of genes and we aren’t testing them all at once.
At least not yet.