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Clinical and Metabolic Genetics
Clinical and Metabolic Genetics

Phenylketonuria Program

Phenylketonuria Program

The treatment of Phenylketonuria (PKU) is one of the great success stories in metabolic disease. Newborn screening programs, first introduced across Canada through the late 1960s and early 1970s, routinely identify infants with high phenylalanine levels. Diagnosis and treatment can begin within the first few weeks of life and prevent the severe, irreversible mental retardation seen in the past, when treatment was not available.

Best practices now promote that persons with PKU remain on dietary treatment for life.  Women with PKU should achieve strict metabolic control of blood phenylalanine levels for at least 3 months prior to and during a pregnancy.

The PKU program at The Hospital for Sick Children provides a comprehensive, family-centred interdisciplinary service including: diagnosis, nutrition management, specialized health assessment and education, psychological and school-related assessment, support for parents and kids in coping with the challenges of a specialized diet, genetic counselling, and preparation for the child/youth's transition to independent self-management.

In addition, we provide training opportunities for medical residents and fellows, and genetic counsellors enrolled in graduate education in the Division of Clinical and Metabolic Genetics and the University of Toronto.

The goal of the PKU Program is to promote optimal physical, developmental and emotional health of young people diagnosed with PKU and Mild Hyperphenylalanemia (MHP).

Team Members

  • Komudi  Siriwardena MBCHB, FRACP (Medical Director)
  • Dawn Cordeiro RN, BN (Clinic Nurse)
  • Valerie Austin BSc, RD (Dietitian)
  • Patty Martinez, MSW, RSW (Social Worker)
  • Stacy Hewson MSc, MSc, CGC, CCGC (Genetic Counsellor)
  • Elizabeth Kerr PhD, CPsych (Neuropsychologist)

Initiatives in PKU Clinic

Blood spot phenylalanine (Phe) results are now being mailed to patients once the results are available.
The metabolic lab is processing blood spots only on Wednesday; the spots need to be in the hospital by Tuesday in order for processing that week.


The goal of the PKU Program is to promote optimal physical, developmental and emotional health of young people diagnosed with PKU and Persistent Benign Hyperphenylalanemia.

Current Research Projects

PKU 015
Funded by Biomarin
Principal Investigator: K. Siriwardena
North American Multi Center Trial
7 year trial ages 0-6

“A Phase 3b Open-Label Study to Evaluate the Effect of Kuvan® on Neurocognitive Function, Maintenance of Blood Phenylalanine Concentrations, Safety, and Population Pharmacokinetics in Young children with Phenylketonuria”
This study began at SickKids in November 2009, and is a 7 year study from date of enrolment for children with PKU who are between the ages of 0 and 6 at study start.
The purpose of this study is to evaluate intellectual development, body growth, and blood phenylalanine levels in young children who are taking Kuvan® in addition to treatment with a phenylalanine restricted diet. The study will also evaluate if Kuvan® is safe to take for a very long time.

PKU 016
Funded by Biomarin
Principal Investigator: K. Siriwardena
North American Multi Center Trial

“A double-blind, placebo-controlled, randomized study to evaluate the safety and therapeutic effects of sapropterin dihydrochloride (Kuvan®) on neuropsychiatric symptoms in subjects with phenylketonuria”

Recruitment stared in July 2011.  All age appropriate patients will be contacted to determine interest and perform screening for eligibility.

This study is a 30 week study for patients with PKU aged 12 years or older at study start. The purpose of this study is to evaluate the safety and effects of Kuvan® when used in patients who have PKU and who may have symptoms of ADHD, depression and/or anxiety. In addition, this study will provide guidance in the care of PKU patients by defining how many PKU patients have these symptoms, and how severe they are in those patients

For any research related inquiries please contact Ashley Orton, study coordinator at 416-813-2646

Adult Patients

At present there is no facility in the Greater Toronto Area able to take the adult PKU population, so they have remained at The Hospital for Sick Children.  Obviously this is a disservice to this population as we are not able to provide all the required services (ie: bone mineral density, social work and psychology/psychiatric services), and have to try and obtain them through local family physicians.

It is our goal to find a suitable adult facility to accept our adult PKU patients. Currently negotiations are in place with another teaching hospital in Toronto.. However like everything in health care funding is an issue. Once we have a definitive answer and know when our patients will be able to be transferred we will be holding an information day for our adult patients to meet the new team and to ask any questions that they may have.

Maternal PKU

Women with PKU or with MHP are referred to the Special Pregnancy Program at Mount Sinai Hospital for specialize management prior to and during a pregnancy.

Advances in the World of PKU

Although is the metabolic disease that we have been testing for and treating for about 60 years its only been in the past 5-10 years that there have been extreme advances in research and treatments for PKU patients.

Kuvan® (sapopterin dihydrochloride)

Kuvan® is a synthetic formulation of BH4, the co-factor for the enzyme phenylalanine hydroxylase (PAH). PAH hydroxylates Phe through an oxidative reaction to form tyrosine. In patients with PKU, PAH activity is absent or deficient. Treatment with BH4 can activate residual PAH enzyme, improve the oxidative metabolism of Phe, and decrease Phe levels in some patients. Kuvan is not a substitute for the Phe restricted diet, but is meant to be used in conjunction with dietary treatment.

Kuvan® was approved for use in June 2010 by Health Canada. Although it has been approved we have been reluctant to intiate treament in large groups of patients due to the lack of secured funding for the drug. Kuvan is an extremely expensive drug (approx. $33 for 100mg tablet, patients can require up to 20 mg/kg therefore a 50kg patient’s treatment could cost $330/day).  We are hoping that with more research and time the provincial drug plan will incorporate Kuvan® into the medications that they fund.

Mailing Address

The PKU Program
Division of Clinical and Metabolic Genetics
The Hospital for Sick Children
555 University Avenue
Toronto, Ontario
M5G 1X8

For general inquires contact  Ms. Denese Henry 416-813-7654 ext.1480