Information for US healthcare providers

PKU Overview

What is PKU?

Phenylketonuria (PKU) is an inherited disorder caused by a deficiency of the phenylalanine hydroxylase (PAH) enzyme needed to process phenylalanine, which is found in all foods containing protein. High levels of phenylalanine can cause brain damage.1

The incidence of PKU is highest amongst Caucasians, occurring in approximately 1 in 10,000 births.2

Your patients are eligible for JAVYGTOR without a trial if they have responded to sapropterin therapy previously. For patients new to sapropterin therapy, the ACMG recommends a trial to assess their responsiveness to the medication.3


All 50 US states require newborns to be screened for PKU, which is how nearly all cases of PKU are diagnosed. A test is performed using a few drops of blood from a newborn’s heel to determine the level of phenylalanine in the blood.4


Untreated individuals with PKU appear normal at birth, but if they do not restrict the phenylalanine in their diet, they can develop severe intellectual and developmental disabilities. Other signs and symptoms of PKU may include behavioral problems, slow growth, small head size, eczema or skin rashes, seizures, jerking movements of the arms or legs and musty odor of breath, skin or urine, as well as fair skin and blue eyes.5

Living with PKU

Patients and families living with PKU face unique challenges:

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71% of parents of children with PKU experience anxiety about their child’s future6

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28% of parents of children with PKU find it difficult to accept their child’s condition6

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Daily nutritional management and regular monitoring of blood phenylalanine levels can be a constant reminder of the presence of a potential danger6

Find out more about Cycle Vita


Restriction of dietary phenylalanine intake remains the first line therapy for patients with PKU, requiring a decrease in the intake of natural protein and replacing it with a protein (amino acid mixture) source devoid of Phe.3

In addition to dietary therapy, some pharmaceutical treatment options are available, including JAVYGTOR (sapropterin dihydrochloride) Tablets for Oral Use and Powder for Oral Solution.

Find out more about JAVYGTOR


1. National Institutes of Health. Phenylketonuria (PKU). Available at: (Accessed July 19th 2022.)

2. Williams, R. A. et al. 2008. Phenylketonuria: An Inborn Error of Phenylalanine Metabolism. The Clinical Biochemist Reviews. 29(1) 31-41.

3. Vockley J., et al; for the American College of Medical Genetics and Genomics Therapeutic Committee. Phenylalanine hydroxylase deficiency: diagnosis and
management guideline. Genet Med. 2014;16(2):188 200. doi:10.1038/gim.2013.157

4. National Institutes of Health. How do health care providers diagnose phenylketonuria (PKU)? Available at: (Accessed July 19th 2022.)

5. National Institutes of Health. What are common symptoms of phenylketonuria (PKU)? Available at: (Accessed: June 9th 2022.)

6. Witalis, E., et al., 2016. Phenylketonuria patients’ and their parents’ acceptance of the disease: multi-centre study. Quality of Life Research, 25(11), pp.2967-2975.