Rare Disease Report

Rare Disease Spotlight: Phenylketonuria

DECEMBER 02, 2015
Rebekah Harrison
Phenylketonuria, also referred to as PKU is a rare genetic disorder that causes a build up of phenylalanine in the body. People with PKU need to follow a strict diet that linits phenylalanine which is found in mostly proteins. PKU is caused by a mutation in a gene on chromosome 12.
PKU affects approximately 1 in 48,000 newborns.


  • Skin rashes
  • Intellectual disability
  • Delayed social skills
  • Seizures
  • Hyperactivity
  • Musty odor
  • Microcephaly
Pregnancy and PKU
If a woman with PKU does not follow a special diet while pregnant, she may develop a condition called maternal PKU which can cause miscarriage or harm a developing fetus.


  • Newborn Screening: all 50 states require newborns to be screened for PKU. Blood is collected from the newborn’s heel to determine phenylalanine levels.
  • Prenatal DNA test
  • MRI- indicated in older individuals


Dietary Treatment
  • Phenylalanine restriction
  • Supplements
Medical Treatment
  • Tetrahydrobiopterin- naturally occurring cofactor that is clinically proven to be effective in lowering blood phenylalanine levels.

Clinical Trials

  • Liver Cell Transplant for Phenylketonuria- determine whether partial irradiation of the liver and liver cell transplantation can reduce the need for dietary and medical management or could possibly eliminate the need for a special diet and medications to treat this disease for patients with phenylketonuria (PKU) by normalizing phenylalanine levels in the body.
  • Protein Requirements in Children With Phenylketonuria (PKU)- study to help treat and manage pediatric patients with PKU with sufficient protein to ensure proper growth and development.
  • Kuvan's Effect on the Cognition of Children With Phenylketonuria- The study is a single-cohort, interventional, open-label trial to evaluate long-term neurocognitive (NC) outcomes in children aged 4 to 5 years with phenylketonuria (PKU) treated with Kuvan and Phenylalanine-restricted diet over a period of 7 years.
  • PKUDOS: Phenylketonuria (PKU) Demographic, Outcomes, and Safety Registry- The objective of this study is to evaluate the safety of long-term treatment with Kuvan.
  • Neurocognitive Outcomes in Mild Hyperphenylalaninemia (MHP)MHP Study- the study seeks to assess whether higher Phe levels, between 360 and 600µmol/L, are safe with respect to preservation of intelligence and higher cognitive functions.
  • PKU Kuvan Imaging Study- investigators will examine adults with PKU on sapropterin dihydrochloride (Kuvan) treatment for PKU and compare their results to those of subjects with PKU not on Kuvan.
  • Biological Variation of Phenylalanine in Patients With Hyperphenylalaninemia- investigators will look at the variation in blood phenylalanine level over 24 hours. The investigators will measure this in patients with typical PKU who are compliant with the diet and in patients who are not compliant with the diet.


  • National PKU Alliance- actively working to increase coverage for PKU medical foods (formula and low protein food) at both the national and state level.
  • The PKU Foundation- the foundation serves as a central, national fundraising organization with the express purpose of helping those effected with Phenylketonuria.

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