Genetic disorder characterized by deposits of small
crystals in the peripheral cornea and the retina resulting in visual
Bietti Tapetoretinal Degeneration with Marginal Corneal
Rare disease in the occident, but relatively common in
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
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
Jiao X, Munier FL, Iwata F, et al: Genetic linkage of Bietti crystalline
corneoretinal dystrophy to chromosome 4q35. Am J Hum Genet
Kaiser-Kupfer MI, Chan CC, Markello TC, et al: Clinical biochemical and
pathologic correlations in Bietti's crystalline dystrophy. Am J Ophthalmol
Shan M, Dong B, Zhao X, et al. Novel mutations in the CYP4V2 gene associated with
Bietti crystalline corneoretinal dystrophy. Mol Vis