So I can either choose gender (only males can be affected by this defected gene so we would choose to have a girl) or I can have the embryo's scanned for the defect irrespective of sex - but not both because it can cause too much damage to the embryo? Am I on the right track?
Hi Amy

With PGD, they combine the egg and sperm and then grow the 'baby' to the 8 cell stage. They remove one cell and then test it genetically.

Because they only have one cell to test with, they can't do all the genetic tests that they can do on adults (where they get lots of cells from a small blood sample). And they can usually only do one test, because all the DNA from that one cell gets used up in the test.

It is not always possible to look for a specific mutation. It depends on whether the mutation is a small one (e.g. one 'letter' in the gene is the wrong letter) or a big one (e.g. a large section of the gene is deleted). A mutation that effects a large area of the gene is sometimes harder, or impossible to do with PGD.

The genetics clinic or IVF/PGD will be able to help you when they know the gene involved, and the family mutation.

If it is possible to test for the family mutation with PGD, the scientists will first have to devise a specific test for the family mutation. This will take a bit longer than when they are testing for something that they do regularly (ie gender or extra chromosomes). They will devise the test before you start egg collection etc to make sure that it works and will be ready for when its needed. This testing phase will also cost extra on top of the IVF/PGD stuff.

take care,

kate