Designer Babies

I think that it is wrong create a designer baby for any reason. If I had a baby born with a rare disease that was going to give him problems the rest of his life and I could design a baby to save the first, I wouldn't do it. It sounds harsh, but is it as harsh as creating a baby for the sole purpose of saving your first child? The second child wouldn't have been created out of love, he would have been created with a purpose.