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An inherited eye disorder characterized by progressive degeneration of the choroidea, retinal pigment epithelium, and neural retina.

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Progressive Tapetochoroidal Dystrophy.

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Less than 1:100,000 in the general population.

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X-chromosomal recessive transmission. Almost exclusively men are affected, but a few female cases have been described. The responsible gene has been mapped to Xq21.2.

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A point mutation is responsible for impairment in geranyl transferase which affects vesicle transport in retinal cells in choroideremia. Affected males usually first note symptoms in adolescence, experiencing night blindness and peripheral visual field loss.

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Based on the clinical findings of progressive degeneration of the choroidea, with night blindness occurring in the teenage years. The differential diagnosis includes gyrate atrophy of the choroid, diffuse choriocapillaris atrophy and X-linked retinitis pigmentosa. The combination of inheritance mode, ophthalmic examination, visual field testing, and electroretinography (ERG) helps confirm the diagnosis.

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The ERG in affected males may initially show a pattern of rod-cone degeneration. Fundoscopy reveals patchy areas of chorioretinal degeneration, usually beginning in the midperipheral areas of the fundus and manifesting as a ring scotoma. As these areas enlarge, the disease progresses to marked loss of the retinal pigment epithelium and the choriocapillaris, while deep choroidal vessels are preserved. Although the function and anatomy of the central macula is preserved until late in the disease process, affected men rarely retain any central vision beyond the seventh decade of life. Almost one third of these patients also have posterior subcapsular cataracts. Although choroideremia is essentially a retinal degenerative disease, associations with other clinical findings (severe mental retardation, agenesis of the corpus callosum, signs of encephalopathy, (sensorineural and conductive) hearing loss, distal motor neuropathy, and cleft lip and palate have been reported. No effective treatment exists.

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History should demonstrate the extent of retinal degeneration. Check for concomitant diseases as mentioned above.

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In the presence of peripheral motor weakness, the effects of neuromuscular blockade may be enhanced and careful titration to effect will be necessary using a peripheral nerve stimulator. In the presence of severe weakness of the respiratory musculature, extubation at the end of a procedure may have to be delayed until full return of muscle function. The presence or absence of other neurologic findings may influence the anesthetic technique. Patients with this condition may be blind, and the psychological considerations pertaining to this situation should be kept in mind.

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Careful dosing of neuromuscular blockers is recommended in the presence of muscular weakness.

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X-Linked Retinitis Pigmentosa: Retinitis pigmentosa is the most common cause of inherited visual loss (approximately 1:4000 in the general population is affected). It usually begins between the second and fourth decade of life with night blindness and later is followed by tunnel vision. The rate and extent of progression are highly variable. More than 70 different genetic defects have been described, all resulting in retinitis pigmentosa. The X-linked ...

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