Children who have Costello syndrome also have a higher risk for some types of tumors,
which can be benign (not cancer) or malignant (cancer).
What Causes Costello Syndrome?
Costello syndrome happens because of a change (mutation) in a gene called the HRAS
gene. The mutation makes cells grow and divide more than they should. Everyone has
two copies of the HRAS gene. It only takes one changed gene to cause Costello syndrome.
The HRAS gene helps make a protein called HRas. Different changes in the HRAS gene
affect the HRas protein in different ways. That means that two children with Costello
syndrome may have different symptoms, and the symptoms can affect one child more than
A child will have Costello syndrome if he or she:
inherits a change in the HRAS gene from either the mother or father
has a new mutation in the HRAS gene
Most children with Costello syndrome have a new mutation. This means that neither
parent has a change in an HRAS gene. The change is a random accident, so there is
nothing the parents could have done to prevent it.
Costello syndrome is a RASopathy. RASopathies
are genetic conditions that cause similar symptoms because they're caused by a change
in one of the Ras family of proteins, which includes HRas.
How Is Costello Syndrome Diagnosed?
To find out if a child has Costello syndrome, doctors will:
ask about the child's symptoms and
do an exam
order genetic testing to
look for a mutation in the HRAS gene in the child's DNA
send the child to see specialists, who might order these imaging tests:
Meeting with a genetic
counselor can help families learn what to expect and understand how Costello syndrome
can run in families.
What Else Should I Know?
Children with Costello syndrome tend to be friendly and outgoing, but most learn
more slowly than other children of the same age. They'll need regular checkups
so doctors can look for:
changes in the heart muscle
changes in the heart's rhythm
muscle, nerve, and bladder cancer
The medical challenges of Costello syndrome can be stressful for any family. But
you're not alone. The care team will work together to help manage problems, and to
support your family. Ask them how to find local groups that can help your child feel
connected and offer resources for the family.
You also can find information and support online at: