Define "Substantial'

More often than not, I strive to write with a bit of humor and a lighthearted take on whatever is going on. This is not going to be one of those posts. This goes more under the heading of an uncomfortable look at reality.
Recently, I have noticed a lot of articles being shared on social media about Iceland's excitement over "ending" Down Syndrome. Since it is a chromosomal abnormality, their method of "curing" this is actually just killing everyone they suspect might have it before they are born. Their only regret seems to be that they occasionally get false negatives and one of these kids slips through and is born. Personally, this all seems monstrous to me. I can not even being to fathom how an entire country could be so blind to genocide. Even still, there are people who will look past it or make excuses.
My question is, after eradicating this, which abnormality will they target next? Make no mistake, there will be a next, and something after that one, and on and on in an effort to only let "perfect" babies have a chance at life. How far will they go?
In an effort to answer this question, I did a little research. The Royal College of Obstetricians and Gynecologists published a handy guide in 2010 on what constitutes a fetal abnormality that warrants termination when a mother is past 24 weeks of pregnancy. This covers England, Scotland, and Wales.    This is how they define it.
         "There is no legal definition of substantial risk. Whether a risk will be regarded as substantial may vary with the seriousness and consequences of the likely disability. Likewise, there is no legal definition of serious handicap. An assessment of the seriousness of a fetal abnormality should be considered on a case-by-case basis, taking into account all available clinical information."

In short, they don't. It is up to the doctor. To be more specific, if you can get two doctors to sign a paper saying they think there is at least a 50% chance that your child will have something they deem serious, you can abort the baby after 24 weeks.
They go to great pains to make is appear as if it is only used in cases where a child would most likely die shortly after being born or if the mother would die, but that is not how it is written. Consequently, there is a rather well known case in which the Church of England attempted to have a doctor charged with aborting a child after 24 weeks. The baby was diagnosed in the womb as having a cleft palette. An investigation was opened, and it was determined that since two doctors said it was okay, they did not have grounds to charge the doctor who performed the abortion.
In case you are new to knowing me, you should know that I was born with a cleft palette. As you can imagine, I take this case rather personally. When I was born, the doctor told my parents that if you were given a list of birth defects and told you had to pick one for your child to have, a cleft palette would be the one to pick. It is the easiest to fix. No one knows I had one unless I tell them. It took a total of 2 surgeries to correct. Sure, it wasn't a walk in the park, but it was easier to deal with than something like a peanut allergy.  The point is, if they could legally justify aborting a child for a cleft, then they can justify literally anything that they might consider an imperfection.
Killing everyone suspected of having Down Syndrome is a test case. If they can get away with it then they will move to another defect. As prenatal testing gets better, so will the number of things they attempt to end.
It won't be long before they make the case for killing the babies born alive who were missed in the screening. It isn't even that big of a leap. Once you start down the road of deciding who deserves a chance at life, you open the door to debate. It is a debate we will lose.