Ignoring any moral implication I just remind of a simple fact: diseases and defects that are genetically transported, will progressively effect the racial gene pool. So when you medically treat persons with such defects and now they survive until the age when they can multiply where before they would have died and nature would have run natural selection that way, this has, over generations, an effect of the general gene pool.
The number of people with bad eyes who need to wear glasses, is increasing for example. While short sight is not necessarily something that would doom the individual to die in the "wilderness"
, it nevertheless illustrates how the presence of a genetic characteristic - bad eyes in this case - results in this characteristic spreading in the gene pool. That with too bad eyes you would die in the wilderness because you can no longer kill your prey or see where your field is, is minor in this example.
But the number of hemophiliac persons is increasing, too. This is because in modern times they have more often children carrying the genetic defect as well, where as in earlier times they simply died before they could have had children.
Just a reminder of biological facts, I do not make any moral judgment or moral comment here. Just want to remind you that nature is totally unsentimental and does not know man's ideas of morals and ethics.