PKU is a rare, inherited metabolic disorder that, if untreated, causes mental retardation. Approximately one of every 10,000 infants in the United States is born with PKU, which usually results from a deficiency of a liver enzyme known as phenylalanine hydroxylase (PAH). This enzyme deficiency leads to elevated levels of the amino acid phenylalanine in the bloodstream.
All infants in this country undergo blood testing for PKU. The current treatment for this disorder involves dietary modification. When a very strict diet is begun early and maintained, children with PKU can expect normal development and a normal lifespan. The diet generally excludes all high protein foods, such as meat, milk, eggs, and nuts, since all protein contains phenylalanine.
Dietary noncompliance can result in a decline in mental and behavioral performance. Women with PKU must also maintain a strictly controlled diet before and during pregnancy to prevent fetal damage. Scientists are actively exploring nondietary treatments for PKU.
Research on PKU continues to broaden the knowledge base from which informed decisions regarding screening and treatment can be made. After a day and a half of expert presentations and public discussion of PKU epidemiology and genetics, screening strategies, and treatment regimens, an independent, non-Federal panel will weigh the scientific evidence and draft a statement that will be presented on the third day. The consensus development panel addressed the following questions:
- What are the incidence and prevalence of PKU and other forms of hyperphenylalaninemias, and what is known about the genetic and clinical variability?
- What newborn screening strategies are available for diagnosis, what is the effectiveness of these strategies, and what cost-savings are generated by screening and treatment?
- What treatment regimens are used to prevent the adverse consequences of PKU? What is known about the effectiveness of these treatment and management strategies overall and with respect to variables such as time of initiation of dietary management, levels of phenylalanine at various ages, methods for enhancing dietary compliance, duration of dietary management, and dietary regimens for women of childbearing age and other adults?
- Based on this information, what are the recommended strategies for optimal newborn screening and diagnosis and lifelong management and followup of PKU?
- What research is needed to gather information that will optimize the outcome for individuals with PKU and their families?
The primary sponsors of the consensus development conference were the National Institute of Child Health and Human Development and the NIH Office of Medical Applications of Research. Cosponsors included the National Human Genome Research Institute, National Institute of Diabetes and Digestive and Kidney Diseases, National Institute of Neurological Disorders and Stroke, National Institute of Nursing Research, Office of Rare Diseases of NIH, and the Maternal and Child Health Bureau of the Health Resources and Services Administration.