Crouzon syndrome


Crouzon syndrome

Description, Causes and Risk Factors:

Def: Craniosynostosis with broad forehead, ocular hypertelorism, exophthalmos, beaked nose, and hypoplasia of the maxilla; autosomal dominant inheritance, caused by mutation in the fibroblast growth factor receptor 2 gene (FGFR2) on chromosome 10q. Crouzon syndrome with acanthosis nigricans is due to mutation in the fibroblast growth factor receptor 3 gene.

Crouzon syndrome

Crouzon syndrome is an inherited genetic disorder which causes craniosynostosis. In this condition the flat plates of bone that form the skull fuse together early in life, interfering with the growth of the skull, distorting the shape of the head and causing an unusual facial appearance.

Crouzon syndrome is caused by mutations in the fibroblast growth factor receptor-2 (FGFR-2) gene but exhibits locus heterogeneity with causal mutations in FGFR-2 (Crouzon syndrome) and FGFR-3 (Crouzon syndrome with acanthosis nigricans) in different affected individuals. Crouzon syndrome with acanthosis nigricans represents a clinically and genetically distinct entity from the "classic" Crouzon syndrome. Indeed, associated with craniosynostosis, several organs are also affected. A recurrent mutation in FGFR-3 gene Ala391Glu is responsible of this syndrome, which allows for a proper information and genetic counseling.

Premature synostosis of the coronal, the sagittal, and, occasionally, the lambdoidal sutures begins in the first year of life and is completed by the second or third year. The order and rate of suture fusion determine the degree of deformity and disability. Once a suture becomes fused, growth perpendicular to that suture becomes restricted, and the fused bones act as a single bony structure. Compensatory growth occurs at the remaining open sutures to allow continued brain growth. However, multiple sutural synostoses frequently extend to premature fusion of the skull base sutures, causing midfacial hypoplasia, shallow orbits, a foreshortened nasal dorsum, maxillary hypoplasia, and occasional upper airway obstruction.

It may be clear as soon as a baby with Crouzon syndrome is born that they have unusual features. As they grow, the shape of the head may distort further causing various problems.

The condition is inherited in an autosomal dominant way, so that each child of a person with Crouzon syndrome has a 50 percent chance of inheriting the condition. However, in about half of all cases the syndrome has resulted from a new mutation (that is, neither parents were affected).

Incidence of Crouzon syndrome is currently estimated to occur in 1 out of every 25,000 people out of the general population.

Symptoms:

Common problems in Crouzon syndrome include:

    Premature fusion of skull bones, including those around the eye and upper jaw.

  • High, prominent forehead.

  • Beak-shaped nose.

  • Abnormalities of the eyes, including hypertelorism (wide spacing), exophthalmos (protrusion), divergent strabismus (squint).

  • Increased pressure inside the skull.

  • Hydrocephalus (too much cerebrospinal fluid in the brain cavities).

  • Damage to the optic nerve.

  • Small upper jaw and short upper lip, with overcrowding of teeth.

  • Deafness due to blockage of the ear canal.

  • Obstruction of the airways.

  • Learning disabilities in about 12 per cent of cases.

  • Thickening of the skin and abnormal pigmentation in about 5 per cent of cases.

Other clinical features include hypertelorism, exophthalmos, strabismus, beaked nose, short upper lip, hypoplastic maxilla, and relative mandibular prognathism. Unlike some other forms of autosomal dominant craniosynostosis, no digital abnormalities are present.

Diagnosis:

Diagnosis of Crouzon syndrome usually can occur at birth by assessing the signs and symptoms of the baby. Further analysis, including radiographs, magnetic resonance imaging (MRI) scans, genetic testing, X-rays and CT scans can be used to confirm the diagnosis of Crouzon syndrome.

Other imaging may include:

    Skull radiography.

  • Cervical radiography.

  • Limb radiography.

Immunohistochemical analysis of cranial sutures, performed with labeled anti-FGFR2 antibodies, reveals that sutures from children with Crouzon syndrome demonstrate lower levels of FGFR-2 activity in both stenosed and nonstenosed sutures compared with children with a nonsyndromic isolated coronal stenosis.

Treatment:

Like other genetic conditions, Crouzon's cannot be 'cured'. But with the right help and care, most children lead a relatively normal life.

Surgery to unlock and move the bones of the skull, especially early in life, may be vital to prevent or treat increased pressure on the growing brain. It may also be used to reconstruct the appearance of the face and relieve protrusion of the eyes.

Excessive fluid around the brain (hydrocephalus) may need to be drained by inserting a tube called a shunt. Other specialist help, for example, to treat dental, eye or ear, nose and throat problems, is often needed.

Long-term supportive treatments such as speech therapy, psychological and educational help, and genetic counseling for the family are also important in helping the child to reach their potential.

NOTE: The above information is for processing purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.

DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.

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