I am also from the UK – the reason PKU patients in the UK are not routinely offered a kuvan trial is because the NHS will not fund it at the moment.
I disagree with the statement that all patients are growing up just fine on the PKU diet. Our almost 4 year old daughter has had digestive issues (she didn't do a poo for almost three weeks after starting the baby PKU formula; all other gastro problems were ruled out but we stayed in hospital for 5 days only for a gastroenterologist to conclude it was the formula) and growth delay (we have been seen by private and NHS endocrinologists and they can find no endocrine problems with her, but I have found numerous research papers about PKU patients having growth and bone age delays on the low protein diet) which we have only been able to put down to the synthetic low protein diet.
CLEARLY I am not saying she or anyone should not be on the diet – the benefits far outweigh the risks. But I also think we in the UK should beware of becoming complacent about accepting the diet as our only option when there other other potentially useful therapies available. These are already being used in the US and other European countries. There is growing evidence that Kuvan therapy is effective FOR SOME PEOPLE. It is clear that the diet is not perfect; it is unpalatable, there are side effects (such as constipation) and as is evident by the numbers of adults not on diet, it is not always easy to stick to. As the mother of a girl with PKU, I also worry about problems with pregnancy should she not be following a strict diet.
Also, I am not saying Kuvan is an answer for everyone. As Breamarie said, it does not work for every patient. But, as she also says, it has brought other benefits to her such as more energy and focus.
I for one would like my daughter to have the advantage at least of doing a kuvan trial to see if she would respond. If it meant she could have, say, 8 or 10 grams of protein a day rather than her current 5 it could make a big difference to her everyday life. Add to that the potential for her to do better at school, have better mental health, and have better dietary adherance when she enters her teen and reproductive years, and I think it is worthwhile.
I think the more choice PKU patients have the better and I hope the UK government sees fit to start providing funding for Kuvan soon.