For most parents, the prick heal test is part of the normal routine in the hospital after birth.
One in 4,500 babies in Ireland are born with PKU and although the condition is treatable, it is a major change for both the child and family.
To mark the 12th annual World Rare Disease Day, we were joined this morning by Conor Byrne, and his son Jacob who was diagnosed with PKU at birth and Jenny McNulty, Senior Metabolic Dietitian, Temple Street Children's University Hospital.
Are you sometimes confused about what to wear for those special occasions? Or maybe you worry about which is the right fork to use, or when to take your hat off at a wedding, or if you should send a thank you card instead of a text?