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For twelve-year-old Kellen Brown, preparing for a sleepover is far more challenging than for most boys his age. He must prepare several servings of his special dietary formula ahead of time, along with small portions of low-protein snacks.

“Kellen can’t have regular potato chips, Doritos, Cheetos, or regular pretzels,” his mother, Christine Brown, explains. He can eat fruit and some vegetables, but grains, eggs, nuts, dairy, meat, and legumes are all off-limits.

Kellen and his fifteen-year-old brother Connor both have phenylketonuria, or PKU, a rare genetic condition in which the body has difficulty breaking down phenylalanine (Phe), an amino acid found in all natural protein. Elevated blood Phe levels can be directly toxic to the brain.

When Phe levels are high or uncontrolled, people with PKU can experience symptoms that have lasting impacts on the brain, including behavior or social problems, feeling “foggy,” inattention, depression, anxiety and irritability. In order to prevent many symptoms of PKU, Kellen and Connor must monitor the foods they eat. In a cruel paradox, “the skills [PKU patients] need to effectively manage the diet are the first skills [they] lose” if they don’t stick to the diet, Christine explains.

Dr. Barbara Burton, Professor of Pediatrics at Northwestern University School of Medicine and Director of its PKU Treatment Program, has treated over 300 PKU patients throughout her 40 years in the field. For PKU patients, “Everything’s hard,” she says, including activities such as reading a book. “They may go to the grocery store for three things and only remember one.”

From a cursory perspective, PKU patients seem to function well in society, so both doctors and family members often fail to realize that they’re sick. “They can work, go to school, have a family, but underneath that, they’re struggling tremendously,” Dr. Burton explains.

Christine receives daily emails from her sons’ schools, listing exactly what they ate for lunch. She can then determine how much protein the boys can have for dinner. Today, Kellen had a typical PKU-friendly lunch: one serving of dietary formula, low-protein pizza with non-dairy cheese, applesauce, chopped romaine lettuce, and grapes.

“Most people with PKU can’t manage their condition successfully with dietary therapy over the course of a lifetime,” Christine explains. “It takes a lot of planning and problem-solving…Sometimes the organization that goes into PKU is even exhausting for me.”

As the Executive Director of the National PKU Alliance (NPKUA), Christine is no stranger to problem-solving. Her organization “works to fund early-stage proof-of-concept research to both expand basic knowledge about PKU and also to accelerate the timeline in drug development.”

Since newborn screening for PKU began in the 1960s, “everyone thought PKU was fixed,” Dr. Burton explains. “PKU is the one genetic disease that we have a treatment for,” she says, referring to the dietary protein restriction and supplementation with phenylalanine-free supplements. “PKU care was sort of an afterthought.”

However, “the diet is not successful for most patients as long-term therapy due to its restrictive nature,” Dr. Burton explains. She also describes the health risks associated with a low-protein diet, namely vitamin and trace mineral deficiencies that can lead to impaired growth in children and decreased overall health in adults.

BioMarin has been a pioneer in PKU research for over 15 years by developing treatment options designed to lower Phe. The company is responsible for the only two FDA-approved treatments that are currently on the market, Palynziq (pegvaliase-pqpz) and Kuvan (sapropterin dihydrochloride). Palynziq is a prescription medication used to lower blood levels of Phe in adults with PKU who have uncontrolled blood Phe levels above 600 micromol/L (10 mg/dL) on their current treatment. Palynziq is only available through a restricted program and can cause a severe allergic reaction (anaphylaxis) that may be life threatening and can happen any time during treatment with Palynziq. See the Important Safety Information below. Kuvan is approved to reduce blood Phe levels in people with a certain type of PKU and is to be used in conjunction with a Phe-restricted diet.

“There’s a special place in my heart for BioMarin,” says Dr. Burton. “There was no interest in PKU from any pharmaceutical companies before BioMarin got in the business.”

Dr. Holly Weng, Executive Medical Director at BioMarin, highlights the patient-centric model that makes BioMarin uniquely equipped in the PKU sector: “Our research has been contingent on strong partnerships with physicians, patients, and patient organizations. The support of key patient groups like the NPKUA has been critical to understanding patients’ perspectives of their disease.”

Dr. Burton agrees: “There’s a very good symbiotic relationship between BioMarin and those who are caring for patients with PKU. The relationship with the medical community and patient community is extremely strong.”

“We want to develop different treatments that would meet different patients’ needs and serve the patients,” Dr. Weng remarks.

To learn more about this rare disease and access other available resources, go to

KUVAN Important Safety Information
It is not possible to know if KUVAN will work for you without a trial of the medicine. Your doctor will check your blood Phe levels when you start taking KUVAN to see if the medicine is working.

Starting KUVAN does not eliminate the need for ongoing dietary management. Any change to your diet may impact your blood Phe level. Follow your doctor’s instructions carefully. Your doctor and dietitian will continue to monitor your diet and blood Phe levels throughout your treatment with KUVAN to make sure your blood Phe levels are not too high or too low. If you have a fever, or if you are sick, your Phe level may go up. Tell your doctor and dietitian as soon as possible so they can make any necessary changes to your treatment.

Children younger than 7 years old treated with KUVAN doses of 20 mg/kg per day are at an increased risk for low levels of blood Phe compared with children 7 years and older. Frequent blood monitoring is recommended in this population to ensure that blood Phe levels do not fall too low.

Tell your doctor if you have ever had liver or kidney problems, have poor nutrition or have a loss of appetite, are pregnant or plan to become pregnant, or are breastfeeding or plan to breastfeed.

KUVAN is a prescription medicine and should not be taken by people who are allergic to any of its ingredients. KUVAN and other medicines may interact with each other. Tell your doctor about all the medicines you take, including prescription and over-the-counter medicines, vitamins, herbal and dietary supplements.

If you forget to take your dose of KUVAN, take it as soon as you remember that day. Do not take 2 doses in a day. If you take too much KUVAN, call your doctor for advice.

The most common side effects reported when using KUVAN are headache, runny nose and nasal congestion, sore throat, diarrhea, vomiting, and cough. Additional adverse reactions reported in connection with worldwide marketing include sore throat, heartburn or pain in the esophagus, inflammation of the lining of the stomach, indigestion, stomach pain, nausea, and nose irritation. These are not all the possible side effects seen with KUVAN. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

KUVAN can cause serious side effects, including:

  • Severe allergic reactions. Stop taking KUVAN and get medical help right away if you develop any of these symptoms of a severe allergic reaction:
    • Wheezing or trouble breathing
    • Nausea
    • Flushing
    • Lightheadedness or fainting
    • Coughing
    • Rash
  • Inflammation of the lining of the stomach (gastritis). Gastritis can happen with KUVAN and may be severe. Call your doctor right away if you have any:
    • Severe upper stomach-area discomfort or pain
    • Blood in your vomit or stool
    • Nausea and vomiting
    • Black, tarry stools
  • Too much or constant activity (hyperactivity) can happen with KUVAN. Tell your doctor if you have any signs of hyperactivity, including fidgeting, moving around or talking too much.

For more information, call BioMarin RareConnections™ at 1-877-MY-KUVAN (1-877-695-8826).

Please read the full Patient Information by clicking here.

PALYNZIQ Important Safety Information
What is the most important information I should know about PALYNZIQ?
PALYNZIQ can cause a severe allergic reaction (anaphylaxis) that may be life-threatening and can happen any time during treatment with PALYNZIQ.

Severe allergic reactions are a serious but common side effect of PALYNZIQ

  • You will receive your first injection of PALYNZIQ in a healthcare setting where you will be closely watched for at least 1 hour after your injection for a severe allergic reaction
  • Your healthcare provider will prescribe auto-injectable epinephrine for you, and will teach you (or your caregiver) and your observer, if needed, when and how to use it if you have a severe allergic reaction
  • If you have a severe allergic reaction during treatment with PALYNZIQ, you will need to receive an injection of epinephrine immediately and get emergency medical help right away
  • Your healthcare provider will decide if you (or your caregiver) are able to give the PALYNZIQ injections, recognize the signs and symptoms of a severe allergic reaction, give an injection of epinephrine, and call for emergency help, if needed
  • Your healthcare provider may recommend that an adult observer (or your caregiver) be with you when you give your PALYNZIQ injection and for at least 1 hour after your injection to watch you for signs and symptoms of a severe allergic reaction and, if needed, give you an injection of epinephrine and call for emergency medical help

Stop injecting PALYNZIQ and get emergency medical care right away if you have any of the following symptoms:

  • Fainting (passing out)
  • Dizziness or lightheadedness
  • Sudden confusion
  • Trouble breathing or wheezing
  • Chest discomfort or chest tightness
  • Fast heart rate
  • Swelling of your face, lips, eyes, or tongue
  • Throat tightness
  • Flushed skin
  • Skin rash, itching, or raised bumps on skin
  • Nausea, vomiting, or diarrhea
  • Losing control of urine or stools

Keep the auto-injectable epinephrine with you at all times during treatment with PALYNZIQ. Read the Patient Information that comes with the auto-injectable epinephrine that your healthcare provider prescribes for you for more information.

If you have a severe allergic reaction, do not continue to take PALYNZIQ until you talk with your healthcare provider. Your healthcare provider will tell you if you can continue treatment with PALYNZIQ.

People taking PALYNZIQ have also experienced allergic reactions other than anaphylaxis. Talk to your healthcare provider if you experience any allergic reactions when taking PALYNZIQ.

PALYNZIQ REMS: PALYNZIQ is available only through a restricted program called the PALYNZIQ REMS (Risk Evaluation and Mitigation Strategy). Talk to your healthcare provider about the PALYNZIQ REMS and how to enroll.

What should I tell my healthcare provider BEFORE starting PALYNZIQ?

Tell your healthcare provider about all the medicines you take, including prescription or over-the-counter medicines, vitamins, and herbal supplements.

Before injecting PALYNZIQ, talk to your healthcare provider right away if you cannot or will not use auto-injectable epinephrine to treat a severe allergic reaction. If you are pregnant or plan to become pregnant while taking PALYNZIQ, talk to your healthcare provider to discuss the risks and benefits of taking PALYNZIQ during pregnancy to you and your unborn baby. If you are breastfeeding or plan to breastfeed, talk to your healthcare provider about the best way to feed your baby if you take PALYNZIQ.

Before injecting PALYNZIQ, read the Medication Guide and Instructions for Use that come with your PALYNZIQ injection.

What should I watch for AFTER starting PALYNZIQ?

PALYNZIQ may cause serious side effects, including:

  • Severe allergic reactions (anaphylaxis)
  • Other allergic reactions to PALYNZIQ can happen during treatment with PALYNZIQ. Contact your healthcare provider right away if you have any of the following symptoms of an allergic reaction including: rash, itching, or swelling of the face, lips, eyes, or tongue. Your healthcare provider may change your dose of PALYNZIQ, stop your treatment with PALYNZIQ for a period of time, or prescribe medicine for you to take before your PALYNZIQ injection to help reduce the symptoms of an allergic reaction

The most common side effects of PALYNZIQ include injection site reactions (such as redness, itching, pain, bruising, rash, swelling, or tenderness), joint pain, headache, skin reactions that spread and last at least 14 days (such as itching, rash, or redness), itching, nausea, stomach pain, mouth and throat pain, vomiting, cough, diarrhea, feeling very tired, and low levels of Phe in your blood.

These are not all of the possible side effects of PALYNZIQ. Speak with your healthcare provider right away about any side effects.

Important notes
Blood Phe testing and diet

  • Your healthcare provider will monitor your blood Phe concentrations during PALYNZIQ treatment
  • Monitor the amount of protein and Phe that you eat or drink. Your healthcare provider may change the amount of protein and Phe you should have in your diet during treatment with PALYNZIQ, depending on the levels of Phe in your blood. Follow your healthcare provider’s instructions about the amount of protein and Phe you should have in your diet

Missed dose

  • If a dose is missed, take your next dose as scheduled and do not take two doses of PALYNZIQ to make up for the missed dose

You may report side effects to BioMarin at 1-866-906-6100 and the FDA by visiting or calling 1-800-FDA-1088.