You can ask to be referred by your GP to a geneticist. We did and found it really helpful. I probably can’t explain it very well but here goes - I’ll try. In summary, they told us that in a simple Tof/OA with no other problems such as CHARGE or VACTERYL etc, they do not know which gene causes the problem and so can not test for what went wrong. But it is very unlikely to be passed on. If there are further complications, I think that they can genetically test the parents and the Tof child to see if it can be passed on. We were told when Freya is thinking of having a family (my husband Dom says she can’t have a boyfriend till she is 30!!) then she should seek genetic counselling as medical science may know more about what caused it. But basically, she would be very unlucky to have a Tof offspring. However, the odds would be increased if she had a child with another Tof partner. Hope that helps. Rachael