What are the other Names for this Condition? (Also known as/Synonyms)

• CFD1 (Craniofacial Dysostosis Type 1)
• Crouzon Craniofacial Dysostosis
• Crouzon Disease

What is Crouzon Syndrome? (Definition/Background Information)

• Crouzon Syndrome is a disorder characterized by early fusion of certain skull bones (craniosynostosis). This prevents normal growth of the skull, which can affect the shape of the head and face
• Signs and symptoms of Crouzon Syndrome may include wide-set, bulging eyes; strabismus (misalignment of the eyes); a small, "beak-shaped" nose; and an underdeveloped upper jaw
• Other features may include dental problems, hearing loss, and/or cleft lip and palate. The severity of signs and symptoms can vary among affected people, even within a family. Intelligence is usually normal, but intellectual disability may be present
• Crouzon Syndrome is caused by changes (mutations) in the FGFR2 gene and is inherited in an autosomal dominant manner
• Treatment may involve surgeries to prevent complications, improve function, and aid in healthy psychosocial development

(Source: Crouzon Syndrome; Genetic and Rare Diseases Information Center (GARD) of National Center for Advancing Translational Sciences (NCATS), USA.)

Who gets Crouzon Syndrome? (Age and Sex Distribution)

• Crouzon Syndrome is a rare congenital disorder. The presentation of symptoms may occur at birth
• Both males and females may be affected
• Worldwide, individuals of all racial and ethnic groups may be affected

What are the Risk Factors for Crouzon Syndrome? (Predisposing Factors)

• A positive family history may be an important risk factor, since Crouzon Syndrome can be inherited
• Currently, no risk factors have been clearly identified for Crouzon Syndrome

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Crouzon Syndrome? (Etiology)

• Crouzon Syndrome is inherited in an autosomal dominant manner. This means that having a change (mutation) in only one copy of the responsible gene in each cell is enough to cause features of the condition
• There is nothing that either parent can do, before or during a pregnancy, to cause a child to be born with Crouzon Syndrome
• In some cases, an affected person inherits the mutated gene from an affected parent. In other cases, the mutation occurs for the first time in a person with no family history of the condition. This is called a de novo mutation

(Source: Crouzon Syndrome; Genetic and Rare Diseases Information Center (GARD) of National Center for Advancing Translational Sciences (NCATS), USA.)

Autosomal dominant: Autosomal dominant conditions are traits or disorders that are present when only one copy of the mutation is inherited on a non-sex chromosome. In these types of conditions, the individual has one normal copy and one mutant copy of the gene. The abnormal gene dominates, masking the effects of the correctly function gene. If an individual has an autosomal dominant condition, the chance of passing the abnormal gene on to their offspring is 50%. Children, who do not inherit the abnormal gene, will not develop the condition or pass it on to their offspring.

What are the Signs and Symptoms of Crouzon Syndrome?

The signs and symptoms of Crouzon Syndrome may include:

• Abnormality of the cervical spine
• Abnormality of the nasopharynx
• Atresia of the external auditory canal
• Coronal craniosynostosis
• Craniofacial dysostosis
• Dental crowding
• Dysgerminoma
• Lambdoidal craniosynostosis
• Sagittal craniosynostosis
• Seizures
• Shallow orbits
• Sleep apnea
• Visual impairment

Based on the frequency of symptoms observed, the following information may be noted:

Very frequently present symptoms in 80-99% of the cases:

• Abnormal facial shape
• Frontal bossing
• High forehead
• Multiple suture craniosynostosis

Frequently present symptoms in 30-79% of the cases:

• Arnold-Chiari malformation 
• Brachycephaly  
• Cerebellar hypoplasia 
• Conductive hearing impairment 
• Conjunctivitis 
• Hypertelorism 
• Hypoplasia of the maxilla 
• Increased intracranial pressure 
• Midface retrusion 
• Proptosis 
• Ptosis 
• Strabismus 
• Turricephaly

Occasionally present symptoms in 5-29% of the cases:

• Abnormality of the sacrum 
• Acanthosis nigricans
• Amblyopia
• Choanal atresia
• Convex nasal ridge
• Headache 
• Hydrocephalus 
• Hypopigmented skin patches 
• Intellectual disability 
• Iris coloboma 
• Melanocytic nevus
• Narrow internal auditory canal 
• Narrow palate 
• Optic atrophy 
• Respiratory insufficiency

(Source: Crouzon Syndrome; Genetic and Rare Diseases Information Center (GARD) of National Center for Advancing Translational Sciences (NCATS), USA.)

How is Crouzon Syndrome Diagnosed?

Crouzon Syndrome is diagnosed on the basis of the following information:

• Complete physical examination
• Thorough medical history evaluation
• Assessment of signs and symptoms
• Laboratory tests
• Imaging studies
• Biopsy studies, if necessary

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Crouzon Syndrome?

The complications of Crouzon Syndrome may include:

• Intellectual impairment, in some cases
• Hearing and vision loss
• Emotional stress

Complications may occur with or without treatment, and in some cases, due to treatment also.

How is Crouzon Syndrome Treated?

• Treatment of Crouzon Syndrome may involve surgeries to prevent complications, improve function, and aid in healthy psychosocial development

(Source: Crouzon Syndrome; Genetic and Rare Diseases Information Center (GARD) of National Center for Advancing Translational Sciences (NCATS), USA.)

How can Crouzon Syndrome be Prevented?

• Currently, Crouzon Syndrome may not be preventable, since it is a genetic disorder
• Genetic testing of the expecting parents (and related family members) and prenatal diagnosis (molecular testing of the fetus during pregnancy) may help in understanding the risks better during pregnancy
• If there is a family history of the condition, then genetic counseling will help assess risks, before planning for a child
• Active research is currently being performed to explore the possibilities for treatment and prevention of inherited and acquired genetic disorders
• Regular medical screening at periodic intervals with tests and physical examinations are recommended

What is the Prognosis of Crouzon Syndrome? (Outcomes/Resolutions)

• The prognosis of Crouzon Syndrome is dependent upon the severity of the signs and symptoms and associated complications, if any
• Individuals with mild conditions have better prognosis than those with severe symptoms and complications
• Typically, the prognosis may be assessed on a case-by-case basis

Additional and Relevant Useful Information for Crouzon Syndrome:

The following DoveMed website link is a useful resource for additional information:

http://www.dovemed.com/diseases-conditions/rare-disorders/