Putting Off Phenylketonuria

Your six-month-old baby has eczema. She also has a small head and slight discoloration of her hair and skin. She could have phenylketonuria.

According to the Cleveland Clinic, phenylketonuria (PKU) is a genetic condition that causes high levels of a substance called phenylalanine to build up in your body. Phenylalanine is found in the body as part of normal biochemical pathways, but problems arise when levels are persistently higher than normal.

Phenylalanine is an amino acid. Amino acids form into proteins. Many of the foods you eat that contain protein and the artificial sweetener aspartame have phenylalanine. If this condition goes untreated, then build up of phenylalanine in your body causes symptoms including issues with cognitive development.

There are various types of phenylketonuria based on the severity of the condition. Types of PKU include classic PKU (most severe), moderate or mild PKU, and mild hyperphenylalaninemia (least severe).

PKU can affect anyone who has mutations in both copies of the PAH gene. Native Americans and those of European descent are more susceptible to the illness.

If a person with uncontrolled PKU has high levels of phenylalanine during pregnancy, this may result in intellectual disability, birth defects and other problems in their baby, even if the baby doesn’t have PKU.

Since diagnosis and treatment occur after birth due to an abnormal newborn screen, noticeable symptoms are very rare. Therefore, symptoms affect those with undiagnosed or untreated cases.

Some symptoms of untreated PKU are:

§  Eczema.

§  Skin and/or hair discoloration.

§  Small head size (microcephaly).

§  A musty odor to their breath, skin or urine.

Some severe symptoms of untreated PKU are:

§  Behavioral issues.

§  Developmental delays.

§  Intellectual problems.

§  Seizures (rare).

Children and adults are at much lower risk for intellectual problems if they suffer from mild hyperphenylalaninemia.

Mutations in both copies of the PAH gene causes PKU. The PAH gene instructs your body to make an enzyme (phenylalanine hydroxylase) that converts amino acids into components (proteins) that your body can use. When your body can’t process the amino acids you consume in your diet, they continue to build up in your blood and tissues. Too much phenylalanine in your body can damage your brain.

PKU is genetic condition that passes to children from their parents in an autosomal recessive pattern. This means that babies receive one copy of the mutated gene that causes PKU from each parent during conception. In many cases, parents are carriers of the gene but don’t have symptoms of the condition.

Healthcare providers perform a blood test after birth to confirm a diagnosis of PKU. Your provider will conduct additional tests to confirm the diagnosis and type of PKU if the phenylalanine levels in the blood sample are high. This is usually done with additional blood and urine tests. Since PKU is a genetic condition, a genetic test can identify the mutation responsible for symptoms.

Though the majority of PKU diagnoses happen after birth, healthcare providers can diagnose PKU at any age if newborn screenings didn’t take place.

To identify levels of phenylalanine in the blood, a phenylalanine screening test is administered. Newborns receive this test between 24 to 72 hours after birth as part of a newborn screen. Your healthcare provider will prick your baby’s heel with a small needle to take a blood sample.

Treatment for PKU is lifelong. This may include a special diet or medication.

Some treatment options may include:

§  Eating a special diet low in phenylalanine but full of other nutrients.

§  Taking vitamins, minerals and supplements.

§  Taking a supplemental medication called sapropterin dihydrochloride (Kuvan) to break down phenylalanine in the body.

There is also a medication called Pegvaliase (Palynziq) which allows people with PKU to eat an unrestricted diet without taking supplements or Kuvan. This medication can be used instead of the enzyme to help break down phenylalanine, which doesn’t work properly in PKU.

A low-protein diet is recommended for people diagnosed with PKU if they aren’t being treated with Pegvaliase. You should avoid foods that are high in protein, such as meat, eggs and dairy products. If you or your child has PKU, you should work with a dietitian to create a diet that is chock full of vitamins and minerals.

Though PKU is a lifelong condition, you can manage your illness effectively and still lead a full and active life. Regular blood tests are needed to monitor the level of phenylalanine in your blood.