Using CRISPR could lead to certain genetic conditions being unjustifiably eradicated
Deciding that certain genetic conditions are "bad" while others are "good," particularly in cases like developmental disorders, is ethically problematic. If we allow scientists or physicians to dictate what sort of genetic conditions are allowed to exist, then this could lead to genetic editing that has more to do with promoting certain physical characteristics as opposed to just curing diseases.
Deciding that certain genetic conditions are "good" while others are "bad," and making decisions that could completely eradicate the conditions that are deemed "bad," poses ethical issues. One example of this is the concept of using CRISPR to edit the genomes of embryos have Down syndrome. The Colorado Cross Disability Coalition (CCDC) is one group that stands firmly against the use of CRISPR to genetically screen embryos for genetic disorders. They pointed out that giving couples the chance to abort fetuses which have genetic disorders, or changing their genetic disorders, leads to seeing disabilities as conditions which should be avoided at all costs. For instance, genetic screening tests often prioritize screening for Down syndrome, with many people who find that their fetuses test positive choosing to abort those fetuses. About 80 to 90 percent of people who genetically screen their fetuses for Down syndrome that get positive results choose to abort their fetus. This leads to a rapidly decreasing population of people with Down syndrome. People with disabilities like Down syndrome have spoken out many times before about how their quality of life is not inherently affected by their having Down syndrome. Assuming that a child with Down syndrome will be a burden or will live an unhappy life, which is the assumption that parents who abort fetuses with Down syndrome make, is incorrect and blatantly harmful. Just because a person with Down syndrome may not live in a society that is oriented around people with Down syndrome (as society is oriented around accommodating people without Down syndrome), that does not mean that people with Down syndrome inherently suffer due to their condition. Eradicating certain genetic conditions based on the assumption that the human having them will suffer could end conditions which do not inherently cause suffering like Down syndrome. Deciding whether or not someone is eugenically fit to survive is inherently unethical and is not a decision that any individual can make.
If scientists, physicians, and bioethicists communicated with people who have genetic conditions which could be treated with CRISPR, they could make informed decisions about what kinds of genetic conditions we should treat and which we should not. For instance, it is unlikely that anyone with multiple sclerosis or sickle cell anemia would advocate for allowing people to have those diseases. One of the biggest distinctions between conditions like Down syndrome and diseases like multiple sclerosis and sickle cell anemia is that diseases like the latter intrinsically cause suffering. Having Down syndrome does not inherently cause a person to suffer. Any suffering that is related to having Down syndrome has much more to do with society being unaccommodating to people with Down syndrome. Discrimination, alienation, and and not having the same rights as other people may be challenges for people with Down syndrome, but that does not mean that having Down syndrome is the same as having a genetic condition that inherently causes pain and suffering such as sickle cell anemia. Making the distinction between genetic conditions which inherently cause suffering and genetic conditions which may only cause suffering as a result of an unaccommodating society could allow us to use CRISPR ethically without worrying about unjustifiably eradicating certain genetic conditions.