When Eating Protein is Deadly - Phenylketonuria

Also known as PKU, phenylketonuria is an inherited disorder that is rare and often picked up by doctors at birth. This disorder causes a buildup of an amino acid, phenylalanine, in the body, as the defect occurs in the gene that helps to produce the enzyme that would normally break down this amino acid. Phenylalanine is commonly found in foods containing protein, and consumption of these foods by someone with PKU can lead to serious medical complications.

Signs and Symptoms

When a baby is first born, there are usually no symptoms or signs present. Many countries now test babies immediately after birth to identify the presence of PKU. When symptoms do occur, they can range from mild to the severe. These can include:

• Delayed development
• Intellectual disability
• Psychiatric disorders
• Behavioral problems
• Social and emotional problems
• Seizures and other neurological problems
• Weak bones
• Hyperactivity
• Eczema and rashes
• Unusual breath odor
• Musty smell on the skin and in the urine
• Blue eyes and fair skin
• Microcephaly

Genetic Risk

PKU is purely genetic, and both parents must have the defective gene for it to be passed on. People can be carriers of the gene without developing the disorder, so it is difficult to try and predict whether or not a baby will be born with PKU. If just one parent has the gene, the disorder will not develop in the child, but the child could become a carrier.

PKU and Pregnancy

The health risks are greater in pregnant women with PKU, particularly if they don’t follow their special diet. If the phenylalanine levels increase during pregnancy, there is a chance that the woman will miscarry, or cause serious harm to the unborn child. This is also true for women who only have mild PKU.

Although there is a low risk of the baby of a mother with PKU to inherit the disorder, there can still be serious complications and consequences following the birth, which are almost the same as having PKU. These include:

• Delayed development
• Intellectual disability
• Microcephaly
• Heart defects
• Low birth weight
• Behavioral problems

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Many of these babies will often need to spend time in intensive care units following their birth. It is therefore vitally important for pregnant women with PKU to strictly follow the special diet during their pregnancy to protect themselves and their baby. Regular monitoring and checkups by a health professional throughout pregnancy are also essential. The sicker the mother gets, the greater the risk to the child.