Weaver Syndrome

What is Weaver syndrome?

Weaver syndrome, also called Weaver-Smith syndrome, is a genetic condition that causes bone overgrowth. The condition may also cause changes to the shape and appearance of your face and the size of your head. It can also affect other muscles and parts of your body.

Weaver syndrome affects each person differently. The most common characteristic is tall stature. If you or your child have Weaver syndrome, you may have less muscle tone, poor coordination and bent or distorted hands or feet. People with Weaver syndrome may also have intellectual disabilities ranging from mild to severe.

How common is Weaver syndrome?

Weaver syndrome is very rare. Experts have only identified this condition in about 50 people in the world.

How does Weaver syndrome affect overall health?

This condition may raise a child’s risk of getting neuroblastoma, a type of cancer that usually affects children under 5. Some children also have congenital heart disease (present at birth), which may require surgery. With regular medical care, however, many children with Weaver syndrome live through adulthood.

What causes Weaver syndrome?

Weaver syndrome is a type of genetic disorder. A genetic disorder is a condition that occurs when genes mutate (change). The gene involved in Weaver syndrome is the EZH2 gene. The EZH2 gene mutation causes bone overgrowth and a chain reaction that affects other genes throughout the body. This chain reaction explains why Weaver syndrome can affect different muscles, bones and organs.

Experts don’t fully understand how the EZH2 gene mutation leads to Weaver syndrome. About half of all people with Weaver syndrome inherited the gene mutation from one parent. If a mother or father has the EZH2 gene mutation, they have about a 50% chance of passing it to their child with each pregnancy.

Weaver syndrome isn’t always passed down from a parent. Some people get the EZH2 gene mutation, even if they don’t have a parent with the mutation.

What are the symptoms of Weaver syndrome?

Signs of Weaver syndrome may appear in your baby before birth. On a prenatal ultrasound, your provider may notice that your baby’s bones are longer than average. Your provider may diagnose your baby with macrosomia, which means your baby is larger than average.

If your newborn has Weaver syndrome, they may have a longer body length or a higher birth weight. Babies with Weaver syndrome usually have a low-pitched cry that sounds hoarse or scratchy.

In some cases, your baby may not have obvious symptoms until they are a few months old.

Your provider may tell you that your baby has “advanced bone age,” which means their bones are maturing faster than normal. Your baby’s growth may be so fast that it’s off the growth charts.

Weaver syndrome may cause differences in the appearance of the head or facial features, such as:

• Broad forehead.
• Extra skin over the inner corner of the eyes (epicanthal folds).
• Eyelids that slant down (down-slanting palpebral fissures).
• Eyes that are far apart (orbital hypertelorism).
• Large head (macrocephaly).
• Large or low-set ears.
• Longer groove between the upper lip and nose.
• Small lower jaw (micrognathia).

Weaver syndrome can also affect other body parts or systems. If you or your child has Weaver syndrome, you may also have:

• Congenital heart conditions.
• Clubfoot or metatarsus adductus (front half of the foot turns inward).
• Elbows or knees that will not straighten.
• Fingers that cannot straighten (camptodactyly) and wide thumbs.
• Joint deformities in the toes.
• Intellectual disabilities.
• Loose muscles in the abdomen, which can lead to a hernia.
• Scoliosis (curvature of the spine).
• Tightness in arm and leg muscles.
• Trouble meeting developmental milestones in infants and toddlers.

How is Weaver syndrome diagnosed?

If your provider suspects Weaver syndrome, they may perform genetic tests to look for the EZH2 gene mutation. Genetic testing involves taking a small sample of blood and sending it to a genetic testing lab.

In some cases, your provider may look for several different gene mutations to rule out other genetic conditions. This test is a genetic testing panel. Some genetic conditions, such as Sotos syndrome, have similar symptoms to Weaver syndrome. Your provider uses a genetic testing panel to determine which gene mutations you or your child may have.

How is Weaver syndrome treated?

There is no cure for Weaver syndrome, but your provider can create a care plan that helps you or your child manage the condition. For example, a care plan might include:

• Behavioral health care for intellectual disabilities.
• Cardiovascular care to treat and manage congenital heart conditions.
• Extra support for school and learning, such as a tutor or counselor.
• Orthopedic surgery or procedures for problems with joints, hands or feet.
• Physical therapy to develop muscle strength and coordination.

How can I prevent Weaver syndrome?

There is no known way to prevent Weaver syndrome. Although children can inherit Weaver syndrome from a parent, it also occurs without a family history. A parent could be a carrier of the gene mutation and not know it.

How do I know if I’m at risk?

If you have an inherited condition or known gene mutation in your family, ask your provider about genetic testing. Genetic tests can look for certain gene mutations that can cause health problems. These tests can provide you with information about genetic conditions that you could pass on to your children.

What is the outlook for Weaver syndrome?

There is no cure for Weaver syndrome, but people with this condition can live healthy lives. See your provider regularly to manage symptoms and get the care you need. Although some children with Weaver syndrome get neuroblastoma, many of them do not. Your provider may tell you about neuroblastoma symptoms to watch for so your child can get additional tests if needed.

When should I seek care?

See your provider regularly for checkups and to discuss physical or mental health concerns. Attend well visits and follow your provider’s care plan. Follow the same approach if you have a child with Weaver syndrome. Contact their provider if you notice possible symptoms of neuroblastoma, which include:

• Bulging eyes or dark circles under the eyes.
• Bump or lump in the neck or torso.
• Diarrhea, upset stomach or loss of appetite.
• Fatigue with fever or cough.
• Lumps under the skin that may look blue or purple.
• Pale skin.
• Swollen belly.
• Trouble breathing.
• Weakness or paralysis in the legs and feet.

A note from Cleveland Clinic

Weaver syndrome is rare and affects each person differently. With proper medical care, you or your child can get the support you need to manage symptoms and live the healthiest life possible. See your provider regularly so you can discuss any physical or mental symptoms and get the care you need.