Preimplantation genetic diagnosis... What do you think?!?

Question

Pre-Implantation Genetic Diagnosis (PGD) is a test that screens for genetic flaws among embryos used in in vitro fertilisation (IVF). With PGD, DNA samples from embryos created in vitro by the combination of a mother’s egg and a father’s sperm are analyzed for gene abnormalities that can cause serious genetic illnesses. This procedure is harmless to the embryo, as it occurs about three days after conception when the embryo is at the four to ten cell stage of development, a point at which the cells are totipotent.

Now, this will mean that some embryos will be disgarded... But PGD could conceivably eradicate all human genetic disease....
While PGD does raise major ethical questions, this scepticism is a little misplaced. Far from PGD devaluing the worthiness of the life of a child suffering from a severe genetic illness, it gives us our first glance at the possibility of entirely eradicating these illnesses.

Answer 1

Actually I don't think it's likely this will eradicate all human genetic disease. Many diseases aren't a problem when they are on only one gene (we have two of most genes) - but will turn into one when it's on both genes. A famous example is sickle cell disease. When only some of the red blood cells are affected, it protects against malaria: that's what happens if only one gene caries the disease. When both cells carry it, it is a problem: sickle cell disease.

So in that case the reason the disease exists, is because the gene helps protect against another disease.

For Christians reading this: this is one clear example of how evolution works: the disease stays in the population (at low frequencies), because the gene that causes the disease helps protect against malaria.