Zellweger spectrum disorder (ZSD)

What happens in this disease?

Peroxisomes are tiny sacs inside the cell that break down certain fats and harmful substances. In this disease, peroxisomes do not form at all or work poorly. Very long-chain fats build up. The brain, liver, kidneys, eyes and ears can be affected. There are severe, intermediate and mild forms.

Which symptoms can occur?

Symptoms vary greatly from person to person. In the severe form they begin at birth; in the mild form they begin later.

• Floppy muscles and feeding difficulties
• Seizures (fits)
• Hearing loss and vision problems
• Liver problems and jaundice
• Developmental delay
• Distinctive facial features (in the severe form)
• Tooth enamel problems and thinning of the bones (sometimes)

How is it diagnosed?

The first step is to measure very long-chain fats in the blood. Other peroxisome tests are also done on blood and urine. The diagnosis is confirmed with a genetic test.

Treatment and care

Care focuses on the symptoms and is the work of a team. Hearing aids, glasses and cataract surgery can help. A feeding tube into the stomach may be needed. Supplements of fat-soluble vitamins may be used. In the USA, there is an approved bile acid treatment for peroxisome disorders. The adrenal glands, bones and teeth are checked regularly. Early special education and physiotherapy are important. The doctor who follows the disease decides which treatment is suitable.

For the family: inheritance and genetic counselling

The disease is passed on through recessive inheritance. The mother and father are usually healthy carriers. For a couple who are both carriers, the chance of having an affected child is 1 in 4 in each pregnancy. If the gene change is known, diagnosis during pregnancy is possible. Genetic counselling is recommended for the family.