So, I was reading about aneuploidy and how a zygote with one extra or less chromosome usually would not survive to full term. I suppose this happens because aneuploidy leads to some kind of protein imbalance. So, in case of monosomy we would have a shortage of proteins, and in case of trisomy we would have an excess of proteins.
On the other hand, a conventional argument for having two copies of each gene is that, if one gene gets corrupted because of some kind of mutation, we still have another copy that produces the correct protein. So, in case of a recessive genetic disorder, the zygote can survive even with half the amount of protein.
My question is then, why can't monosomic aneuploidy be looked at the same way? Moreover, I read that monosomic aneuploidy is almost always fatal, while trisomic aneuploidy is sometimes tolarated.