Hyperphenylalaninemia Longitudinal Study

Protocol Description

The purpose of this observational study is to learn more about people who have inherited conditions that cause hyperphenylalaninemia and who are treated with the current standard of care. People with hyperphenylalaninemia have elevated levels of phenylalanine, or Phe, in the blood, which can negatively affect the brain. As a longitudinal study, the research program will follow participants over an extended period of time. Researchers will collect neuropsychological information along with data on bone health and growth outcomes, quality of life and patient-reported outcomes across the lifespan. Longitudinal studies can provide insights that can lead to improved treatments in the future.

Eligibility Criteria

The study is accepting participants of all ages, born after 1963, who have hyperphenylalaninemia.
Males and Females: All ages


In addition to their regular clinic visits, participants will receive examinations and testing specific to this study. If not completed previously, genotype testing will be done to confirm the diagnosis of the specific inherited condition causing hyperphenylalaninemia. Participants’ bone density may be tested through DEXA scans, and neuropsychological testing will also be conducted.
Visits: Following a screening and baseline visit, study visits will occur annually.
Duration: 5 years

Status: Open to Enrollment

Source(s) of Support

Phenylalanine Families and Researchers Exploring Evidence Consortium (PHEFREE Consortium)

Additional Information

Genetic and Genomic Medicine Research

Primary Investigator

Georgianne Arnold, MD

Contact Information

For more information about the study or enrollment, please contact:
Clinical Research Coordinator Angela Leshinski