Phenylketonuria Definition, Reason, Symptoms, Treatment & Prevention
Understanding
Phenylketonuria is a rare genetic disease that causes a buildup of the amino acid phenylalanine in the body. The cause is an abnormality in the gene that functions to form the enzymes needed to digest phenylalanine. Without this required enzyme, phenylalanine buildup can occur, especially when individuals with phenylketonuria eat foods that are high in protein.
Wrong eating that looks trivial can cause serious health conditions. So throughout life, individuals with phenylketonuria – including infants, children and adults, must follow a diet that limits intake of phenylalanine, which is found in most foods that contain protein.
Symptom
Newborns with phenylketonuria initially do not show any symptoms. Without treatment, signs and symptoms of phenylketonuria may begin to appear in the first few months.
Signs and symptoms of phenylketonuria can be mild or severe and can include a number of problems, such as:
- Intellectual disability (formerly known as mental retardation)
- Slower development process compared to other children his age
- Behavioral, emotional, and social disorders
- Mental disorders
- Neurological disorders, which may include seizures
- Hyperactive
- Low bone strength
- Rashes on the skin
- Small head size
The most severe type of this disease is classic phenylketonuria. Children and adults with less severe types of phenylketonuria, where the enzymes are still functioning although limited, have a lower risk of developing brain damage.
However, most children with phenylketonuria still need a special diet to prevent intellectual disability or other complications.
Reason
Phenylketonuria is caused by a genetic mutation. In individuals with this condition, the gene abnormality causes the loss or lack of an enzyme needed to digest amino acids (phenylalanine). As a result, there will be a buildup of phenylalanine in the body. This buildup can cause problems when individuals with phenylketonuria often eat foods rich in protein, such as milk, cheese, nuts, or meat.
A child with phenylketonuria generally gets inherited genes from both parents, both from the mother and father. This pattern of inheritance is called autosomal recessive. This may not be realized because there is a possibility that both parents who have the gene disorder only act as carriers and never show symptoms.
If only one of the parents has a gene disorder, generally a lower risk of passing on the gene disorder to the child. However, the child still has the possibility of becoming a carrier. Often, phenylketonuria is found in children in whom both parents are carriers, but the condition has not been recognized before.
Risk factors for developing phenylketonuria are:
- Having two parents with a phenylketonuria gene disorder. If both parents pass on the gene disorder, the child can experience phenylketonuria.
- Being in a certain racial group. The frequency of gene abnormalities varies by racial group. This problem is less common in individuals of African race than in other races.
- Children of mothers who have phenylketonuria but do not follow a phenylketonuria diet during pregnancy are at risk for birth defects due to high levels of phenylalanine in the mother’s bloodstream.
Diagnosis
Examination for phenylketonuria can be done one or two days after birth. This examination is not carried out in the first 24 hours or before the baby gets protein intake, in order to get more accurate results.
If the test results are positive, the baby will undergo further tests to confirm the diagnosis, including blood and urine laboratory tests. In addition, mothers and babies are also advised to undergo genetic testing to see any gene mutations.
Treatment
Several things need to be considered to treat phenylketonuria, which include:
- Application of a dietary pattern with very limited protein intake, because foods that have protein usually also contain phenylalanine.
- Take a formula for phenylketonuria, which is a special nutritional supplement, for life. This is to ensure that a person with phenylketonuria continues to get a variety of essential proteins and other nutrients needed by the body for growth and general health.
This phenylalanine-free formula provides protein and other essential nutrients in a safe form. Doctors and nutritionists will determine the right type of formula for people with phenylketonuria based on age as well as phenylalanine levels that are safe for the body.
- The safe intake of phenylalanine varies for each individual with phenylketonuria. In general, it is important to continue to consume phenylalanine according to the amount needed for normal growth processes, but should not exceed the body’s tolerance threshold.
- Your doctor can suggest a safe amount by regularly monitoring your diet, growth, and blood levels of phenylalanine. Because the amount of phenylalanine that can be consumed safely is actually very low, people with phenylketonuria are advised to strictly limit all foods that contain high protein.
For example: milk, eggs, cheese, nuts, soybeans, chicken, beef and fish. Potatoes, grains, and other vegetables that contain protein also need to be limited.
Prevention
One way to prevent the occurrence of phenylketonuria in children is to consider genetic counseling before deciding to become pregnant. With this examination, doctors who have expertise in the field of medical genetics can carry out further checks to determine the presence of a phenylketonuria carrier gene from one or both parents. It can also help parents to understand how phenylketonuria is passed down the family tree.