Babies with this disorder cannot process a substance called phenylalanine that is found in almost all food. Without treatment, phenylalanine builds up in the bloodstream and causes brain damage and mental retardation. When PKU is detected early, mental retardation can be prevented by feeding the child a special diet. Mental retardation can be prevented if the baby is treated with a special diet that is low in phenylalanine begun within the first 7 to 10 days of life.
At first, the baby is fed a special formula that contains protein but no phenylalanine. Breast milk or infant formula is used sparingly to supply only as much phenylalanine as the baby can tolerate. Later, certain vegetables, fruits, some grain products (for example, certain cereals and noodles) and other low-phenylalanine foods are added to the diet, but no regular milk, cheese, eggs, meat, fish and other high protein foods are ever allowed. Since protein is essential for normal growth and development, the child must continue to have one of the special formulas which are high in protein and essential nutrients, but contain little or no phenylalanine.
Doh. I would think they could screen couples and tell them that they are both carriers and 1/4 of their childern will have the disease.