How open are doctors now to screening embryos for something like Noonan’s?

This is very much a question of personal choice. The GP can talk through the options with the person. The normal test is 9 or 10 weeks into pregnancy but even though it can indicate the gene is there it can’t always tell how severe the Noonan’s is going to be, and even in multi-generational cases, there may be differences between one generation and another. This needs to discussed sympathetically by the GP with the person in question.