Phenylketonuria Eliza Greenberg

Phenylalanine comes from foods. Meat, beans, even artificial sweeteners- it's in there, and that's how it gets in the body. In most people, phenylalanine hydroxylase(PAH) converts phenylalanine to tyrosine. Phenylketonuria is a metabolic disorder that stops PAH and raises phenylalanine in the blood to toxic levels.

150 different mutations can be to blame for a deficiency in phenylalanine hyrdoxylase, but the results are all the same

In the early 60's, people began to notice infants born with smaller-than-average heads, or microcephaly, had developmental delays, trouble learning motor skills, and even seizures. They spoke up, and research began to find the connecting factor: phenylketonuria

As time progressed without treatment, the symptoms got worse, leading to aberrant behavior, intellectual disability, rashes, and psychiatric symptoms.

The test was simple: a small amount of blood was drawn and tested for phenylalanine levels. If the levels were higher than 600 μmol/L, treatments would begin and should not be stopped through adolescence

If treatment begins early enough, symptoms may never manifest

By 1965, 32 American states were creating laws to screen all newborn children for the disease. By the 70s, screening for PKU was routine in nearly every industrial nation and many other countries.

Blood testing was also recommended for any adult who had not been tested and had an intellectual disability

1 in 10,000 newborns in Europe are diagnosed each year, while in the United States, less than 275 children test positive in a year.

Studies in Europe have found higher rates of PKU in Ireland and TUrkey, while the disease is scarce in Finland

For mild cases, treatment is simple: a low-phenylalanine diet. As long as they keep their levels in check, symptoms can be avoided completely

Scientists have even produced a special formula for infants and toddlers that provide all the nutrients needed without raising phenylalanine levels

Different Foods have different amounts of phenylalanine; on the left are foods the low-phenylalanine diet tries to avoid while the right shows better options.

While there is no record of phenylketonuria turning fatal, left untreated, intellectual disabilities become increasingly severe

Treatment varies based on phenylalanine levels, but the diet is the cornerstone of treatments. Any and all treatments revolve around lowering phenylalanine levels in the blood

For patients diagnosed late, treatments can improve IQ and reverse a little of the damage done by the disease

PKU is an autosomal, recessive metabolic disorder, although the disease appears to pass through breastfeeding as well. Research is still underway on that theory.

If a mother of a newborn or young child has pku, low-phenylalanine formula should be substituted for breast milk or brand-name formula so as not to hike the rise of phenylalanine in the infant's system, even if just as a precaution

Most recent studies being conducted compare treatments of PKU to treatments for other genetic disorders, including Type 1 Diabetes to see if any similarities in mutation could lead to more efficient treatments for both

Europe recently created set guidelines for the treatment of PKU, singling out ten of the 70 known treatments as most effective, cost-efficient, and accessible.

After 50 years, phenylketonuria is far from having revealed all of it's secrets; with time, results will show more efficient treatments that could lead to treatments for other disorders. Researchers hope that treatments could lead to new information on intellectual disability, IQ, and more as well.

Works Cited

Brosco, Jeffrey P., and Diane B. Paul. "The Political History of PKU: Reflections on 50 Years of Newborn Screening." American Academy of Pediatrics, 24 Sept. 2013, pp. 1-3, doi:10.1542/peds.2013-1441. Accessed 3 Feb. 2017.

"Learning about Phenylketonuria (PKU)." National Human Genome Research Institute,, 21 Aug. 2014, Accessed 31 Jan. 2017.

"Microcephaly." Boston Children's Hospital, 2017, Accessed 1 Feb. 2017.

Phenylalanine Levels in Foods. New England Consortium of Metabolic Programs, Boston Children's Hospital, 2017, Accessed 3 Feb. 2017. Table.

Van Spronsen, Francjan J., Prof. "Key European Guidelines for the Diagnosis and Management of Phenylketonuria." The Lancet Diabetes & Endocrinology, vol. 5, no. 1, 9 Jan. 2017, pp. 1-12, DOI: Accessed 1 Feb. 2017.


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