"The cord blood of a child with leukemia would also carry the disease." Really ? AFAIK leukemia isn't a birth disease. Kids (and adults) can develop it at various ages. And environmental factors such radioactivity or heavy metals poisoning can increase the risk significantly. There probably is a huge genetic factor in the odds of having leukemia, so taking your own cord blood may contain a risk of having a new leukemia a few years afterward. But still, that's far from already carrying the disease.

Or I am wrong somewhere ?