Stickler syndrome

Definition

The Stickler syndrome is an autosomal dominant disorder characterized by hearing anomalies, orofacial, ocular and skeletal disorders.
Was first described by Gunner Stickler in 1965, after examining a child who presented progressive myopia, difficulties in the articulation and whose family also had various members with similar symptoms, which led to believe in heredity disease.
Children with a family history of Stickler syndrome have a 50% chance of developing it. The disease affects male and female, and hearing loss one important characteristic of this syndrome.
The syndrome in question is the primary cause of retinal detachment, however, is still unfamiliar disease and therefore hardly identified.

Classification

Stickler syndrome can be divided into types I, II, III.
The syndrome type I represents 75% of cases and is known as the complete form of the syndrome. It is caused by mutations in the COL2A1 gene located on chromosome 12q13 which encodes collagen type II. Its alteration is related to multiple forms of mild midfacial hypoplasi , osteoarthropathy premature, and hearing disorders and altered visual.
The type II phenotype of this syndrome is caused by mutations in the COL11A1 gene located on chromosome 1p21 that is responsible for encoding the alpha 1 chain of type XI collagen, also causing hearing loss, and articular and eye alterations.
There is also Stickler syndrome type III (not ocular), which comes from the mutation of COL11A2 gene on chromosome 6p21.3 and has the function to encode alpha-2 chain of collagen type XI.

Clinical Manifestations

The clinical manifestations of Stickler syndrome are because of abnormalities that occur in the development of connective tissue and primarily affect auditory systems, craniofacial, skeletal and ocular.
The syndrome has a varied clinical condition which makes it very difficult to prediction the severity of the phenotype even if it has knowledge of the molecular changes caused by the mutant gene.
However, the most common features are hearing loss, flat face, micrognathia, cleft palate, severe myopia and bilateral joint involvement with midfacial hypoplasi (Faber et al, 2000).
The table at right shows the prevalence of clinical signs of 25 patients by the NIH (National Institutes Health) with defined mutations in the COL2A1 gene (whose mutation causes Stickler syndrome type I):

Manifestations Otorhinolaryngological

Approximately 20% of people with this syndrome have typical manifestations: flat face, micrognathia and depression of the dorsum of the nose. Although there may be ocular hypertelorism, epicanthal folds, hypoplastic nasal septum, presence of uvula bifida and cleft palate.

Hearing loss, another characteristic of the syndrome can be of 3 types: sensorineural, conductive or mixed.
The sensorineural is present in 80% of patients and the cause seems to result from a primary sensorineural deficit, associated with a change in the epithelium of the inner ear. Another possible factor would be the collagen, which is the largest component of the connective tissue of the inner ear.
Conductive hearing loss due to middle ear dysfunction, accompanying craniofacial anomalies syndrome. Not always identify this deficit is perceived as it may appear so smooth. Only 45% of affected by conductive hearing loss are symptomatic.

Others Manifestations


Myopia usually congenital, is an important signal ophthalmological in the syndrome, affecting approximately 80% of patients and may be associated with strabismus, astigmatism, cataracts, retinal detachment (severe clinical manifestation) and glaucoma.
With respect to the skeletal system may develop abnormal joint surfaces, joint degeneration and premature hyperextensible joints. Elbows, wrists, hips, knees and ankles are frequently affected.

Treatment


Since established the diagnosis of Stickler syndrome is necessary that a multidisciplinary team be used and that they work in a coordinated approach. It is important that it be made ​​an ophthalmological evaluation with subsequent corrections that are at odds with normality. Surgical correction or the use of contact lenses can be used in cases of myopia and astigmatism and prophylactic retinopexy to reduce retinal detachment. The evaluation maxillofacial and ear are also important to check the possibility of making some corrections. Also, due to hearing impairment and hearing, it is necessary that the patient receives special care if this is school age, as this may be facing difficulties in learning. The rheumatologic assessment and monitoring is indicated in older patients, who may benefit through physical therapy for arthropathy.

Conclusion

The Stickler syndrome is still unknown making it necessary to more study both clinical and genetic. The early diagnosis and treatment are extremely importance because these delays can cause several irreversible complications such as deafness and blindness.
Multidisciplinary care and genetic counseling are important for it to be provided better quality of life for patients.

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