We will begin transitioning to another product in the next few months. My 21 year old son has autism in addition to PKU. All change is difficult for those on the autism spectrum. This will be a very difficult transition for him. I am concerned as I see the other manufacturers of metabolic formulas are having difficulty keeping up with the new demand. I imagine the infants would get first priority as they should but imagine not being able to have any form of nutrition or calories as a 21 year old active young man and then losing your ability to focus, sleep, think, interact, etc. I think what is most upsetting is the seemingly lack of understanding by the FDA on how crucial these formulas are to our families. We have to fight with insurance companies to get coverage because they deem these food products and not necessary. This shows a complete lack of understanding of Inborn Errors of Metabolism and now the FDA is showing us the same lack of understanding. Please listen to the coalition of dietitians who work with our families and understand how crucial it is to have metabolic formula. They have seen directly the results of people who have gone off diet and formula. That is essentially what the FDA is forcing us to do. We have nowhere else to turn.