General Condition Information
- Zellweger spectrum disorders
- Zellweger syndrome
What is Zellweger spectrum disorder
Zellweger spectrum disorder (ZSD) is group of inherited (genetic) conditions that prevents the body from properly producing peroxisomes, an essential part of cells. Peroxisomes help make energy and fats and break down toxins.
ZSD occurs when abnormal peroxisomes cannot perform their important functions in the body. This especially affects the brain, nerves, bones, liver, heart, and kidneys.
ZSD can cause a spectrum of signs and symptoms that range from severe, intermediate, to mild. The severe form of ZSD is sometimes called Zellweger syndrome, the intermediate form is sometimes called neonatal adrenoleukodystrophy, and the mild form is sometimes called infantile Refsum disease.
Newborn Screening and Follow-Up
Newborn screening for ZSD requires collecting a small amount of blood from your baby’s heel. To learn more about this process, visit the Blood Spot Screening page.
Screening measures the level of a type of fat called “very long chain fatty acids” in your baby’s blood. Babies with high levels of these substances might have ZSD. Newborn screening cannot tell what type of ZSD a baby has.
If your baby’s blood spot screening result for ZSD is out-of-range, your baby’s health care provider will contact you. Together, you will discuss next steps and follow-up plans.
An out-of-range screening result does not mean that your baby definitely has the condition. It does mean that your baby needs more follow-up testing. To learn more about screening results, visit the Blood Spot Screening Results page.
Your baby may need the following tests after an out-of-range screening result:
- Blood tests
- Urine tests
- Genetic testing using a blood sample
You should complete any recommended follow-up testing as soon as possible. Babies with this condition can have serious health problems right away if they are not diagnosed and treated quickly.
False-positive newborn screening results for this condition are rare. Babies with other conditions that have high levels of very long chain fatty acids may also be detected through this screening. An example of another condition that may be detected is X-linked adrenoleukodystrophy.
Newborn screening helps babies lead healthier lives. If your baby has an out-of-range result, follow up with your health care provider quickly. It is important to follow their instructions. Your baby may need to get treatment right away, even if they are not showing signs or symptoms. In some cases, your baby’s health care provider may decide it is best to watch (monitor) your baby to decide next steps. Careful monitoring and early treatment will help your baby stay as healthy as possible.
Signs and symptoms of ZSD can occur right away at birth or a little later in infancy.
Signs of the condition in severe ZSD may include the following:
- Floppy arms and legs (hypotonia)
- Feeding problems
- Hearing loss
- Vision loss
- Facial features that are different from their parents
Signs of the condition in intermediate or mild ZSD may include the following:
- Developmental delay
- Growing slowly or gaining weight slowly (failure to thrive)
- Hearing loss
- Vision problems
- Liver problems
- Problems with coordination and balance (ataxia)
There are many different genetic causes of ZSD. ZSD is caused when one of several genes, which gives the body instructions for making functioning peroxisomes, does not work.
ZSD may be caused by changes in the PEX1, PEX2, PEX3, PEX5, PEX6, PEX10, PEX11, PEX12, PEX13, PEX14, PEX16, PEX19, or PEX26 genes, among others. Changes in the PEX1 gene are the most common cause of ZSD.
- ZSD is an autosomal recessive condition. Babies inherit the condition when each parent passes down the same nonworking gene to their baby. Only babies with two matching nonworking genes—for example, one nonworking PEX1 from the mom and one nonworking PEX1 from the dad—have this condition. Babies with two nonworking genes that do not match—for example, one nonworking PEX1 from the mom and one nonworking PEX2 from the dad—will not have this condition.
- People with one working copy and one nonworking copy of the gene are called carriers.
- Carriers do not have or develop the condition. However, they may pass down a nonworking copy of the gene to their children.
- If two parents are carriers of a nonworking copy of the gene, they have a 1 in 4 chance of having a child with ZSD.
- Carriers for ZSD often do not know they are carriers before having a child with the condition. In most cases, families have no history of the condition until the birth of a child with ZSD.
- Parents who already have a child with ZSD still have a 1 in 4 chance of having another child with ZSD. This 1 in 4 chance stays the same for all future children.
- Genetic counselors and medical geneticists can help families learn about this condition and the chance of having children with it. Visit the National Society of Genetic Counselors to find a genetic counselor and the American College of Medical Genetics and Genomics to find a medical geneticist.
Treatment and Management
It is important to talk to your health care provider about which treatment(s) are best for your baby. While there are no treatment options available that can stop the progression of ZSD, there are treatments for symptoms of ZSD.
Treatments may include the following:
- Vitamin supplements
- Correction of hearing and vision problems