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Genetic disorder characterized by deposits of small crystals in the peripheral cornea and the retina resulting in visual impairment.

Bietti Tapetoretinal Degeneration with Marginal Corneal Dystrophy.

Rare disease in the occident, but relatively common in China.

Autosomal recessive disorder. The mutation most likely is located on 4q35. New research found mutations in the CYP4V2 gene, which is encoding a protein belonging to a novel member of the cytochrome P450 family. Parental consanguinity is frequently observed.

Underlying systemic disorder of the lipid metabolism has been suggested but never proven.

Refractile deposits found in both paracentral and peripapillary retina and marginal cornea are the most common features of this syndrome. Electrodiagnostic testing shows pathologic changes in the electrooculogram and decreased scotopic and photopic responses in the electroretinogram. Skin biopsies and histologic examination of tissue from corneal and conjunctival biopsies have shown crystal-like cholesterol or cholesterol-ester and complex lipid inclusions in fibroblasts. Similar inclusions are present in circulating lymphocytes.

Patients usually become symptomatic in the third decade of life, manifested by reduced visual acuity and other visual symptoms. Occurrence of this disorder in children has only recently been reported. Clinically, degeneration of the retinal pigment epithelium with glistening intraretinal fundal dots can be found in combination with choroidal vessel sclerosis, marginal corneal dystrophy, and visual field constriction. Patients also complain about progressive hemeralopia (night blindness).

No specific anesthetic considerations concerning this syndrome, and there is no evident impairment of general health.

The same considerations apply as for healthy children undergoing eye surgery. Especially in younger patients undergoing ophthalmic examination under general anesthesia, oculocardiac reflex with profound bradycardia should be expected. The treatment is twofold and includes first stopping the stimulation and second, if still necessary, anticholinergic drugs.

No known pharmacological implications.

Jiao X, Munier FL, Iwata F, et al: Genetic linkage of Bietti crystalline corneoretinal dystrophy to chromosome 4q35. Am J Hum Genet 67:1309, 2000.  [PubMed: 11001583]
Kaiser-Kupfer MI, Chan CC, Markello TC, et al: Clinical biochemical and pathologic correlations in Bietti's crystalline dystrophy. Am J Ophthalmol 118:569, 1994.  [PubMed: 7977570]
Shan M, Dong B, Zhao X, et al. Novel mutations in the CYP4V2 gene associated with Bietti crystalline corneoretinal dystrophy. Mol Vis 11:738, 2005.  [PubMed: 16179904]

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