Information for US patients

Phenylketonuria (PKU) Explained

What is PKU?

PKU is an inherited disorder caused by a deficiency of an enzyme (phenylalanine hydroxylase, sometimes known as PAH). The PAH enzyme is needed to process phenylalanine (Phe), 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

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How is PKU treated?

The first line of therapy to treat PKU is a phenylalanine-restricted diet. This involves medical foods which have been modified to be low in protein, and medical formula which provides the nutrients a person without PKU would typically get from protein.³

In addition to the phenylalanine-restricted diet, some patients with PKU also take a medication called sapropterin dihydrochloride, the active ingredient in JAVYGTOR (sapropterin dihydrochloride). This medication helps the PAH enzyme work more effectively to break down phenylalanine in the body.

JAVYGTOR is not a cure for PKU, but when combined with a phenylalanine-restricted diet it can help keep phenylalanine levels under control, and may help you better manage your condition.

Find out more about JAVYGTOR


1. National Institutes of Health. Phenylketonuria (PKU). Available at: (Accessed February 12th, 2024).

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. JAVYGTOR (sapropterin dihydrochloride). Prescribing Information. Dr Reddy’s Laboratories Ltd.