Crouzon syndrome is a rare inherited disorder in which many of the flexible seams (sutures) in a baby’s skull turn to bone and fuse too early. Early fusion of the skull is the hallmark of a group of conditions called craniosynostoses.
Normally, the sutures in a baby’s skull stay open to let the brain grow. When these sutures close too early and the baby’s brain keeps growing, the skull and face can become misshapen. Signs of Crouzon syndrome can start in the first few months of a baby’s life and continue to progress until his or her second or third birthday.
Crouzon syndrome affects about 5 percent of all babies with craniosynostosis. French neurologist Louis E. O. Crouzon first described this condition in the early 20th century.
People with Crouzon syndrome have a normal life expectancy. Most children with this condition are unaffected intellectually. However, it can alter the shape of the face and cause vision and hearing problems.
Babies with Crouzon syndrome can have symptoms like these:
- short and wide or long and narrow head
- enlarged forehead
- widely spaced eyes
- bulging eyeballs
- crossed eyes (strabismus)
- eyes that point in two different directions
- vision loss
- eyelids that slant downward
- flattened cheeks
- curved, beak-like nose
- small, poorly developed upper jaw
- short upper lip
- protruding lower jaw
- hearing loss
- opening in the lip (cleft lip) or roof of the mouth (cleft palate)
- crowded teeth
- mismatched bite
These symptoms may be more severe in some babies than in others.
A small percentage of children with Crouzon syndrome also have a skin condition called acanthosis nigricans. This condition causes dark, thick, and rough patches of skin to form in folds like the armpits, neck, behind the knees, and groin.
Crouzon syndrome is caused by changes called mutations in one of the four FGFR genes. Usually it affects the FGFR2 gene, and less often the FGFR3 gene.
Genes carry the instructions for making the proteins that direct the body’s functions. Mutations can affect whatever functions a specific protein has.
FGFR2 codes for a protein called fibroblast growth factor receptor 2. As a baby develops in the womb, this protein signals bone cells to form. Mutations to this gene amp up the signal, increasing bone development and causing the baby’s skull to fuse too soon.
A baby only needs to inherit one copy of the gene mutation from a parent to get Crouzon syndrome. If you have this condition, each of your children has a fifty-fifty chance of inheriting it. This inheritance pattern is called autosomal dominant.
In about 25 to 50 percent of people with Crouzon syndrome, the gene mutation happens spontaneously. In these cases, babies don’t need to have a parent with Crouzon syndrome to get the disorder.
Complications of Crouzon syndrome can include:
- hearing loss
- vision loss
- inflammation in the front of the eyes (exposure keratitis) or in the membrane lining the whites of the eyes (exposure conjunctivitis)
- drying of the clear outer covering of the eye (cornea)
- fluid buildup in the brain (hydrocephalus)
- sleep apnea or other breathing problems
Children with mild Crouzon syndrome may not need to be treated. Those with more severe cases should see craniofacial specialists, doctors who treat disorders of the skull and face.
In more severe cases, doctors can perform surgery to open up the sutures and give the brain room to grow. After the surgery, kids will need to wear a special helmet for a few months to reshape their skull.
Surgery can also be done to:
- relieve pressure inside the skull
- fix a cleft lip or palate
- correct a malformed jaw
- straighten crooked teeth
- correct eye problems
Children with hearing problems can wear hearing aids to amplify sound. Kids with this condition may also need speech and language therapy.
Doctors diagnose Crouzon syndrome by looking at the shape of the baby’s skull and face during an exam. They also use imaging tests such as X-rays, computed tomography (CT), and magnetic resonance imaging (MRI) scans to look for fused sutures and increased pressure in the skull. Tests to look for mutations in the FGFR2 gene can also be done.