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NM Boisvert, RM Hansen, ER Elias, M Irons, AB Fulton; Effect of Cholesterol Deficiency on Retinal Cell Function . Invest. Ophthalmol. Vis. Sci. 2002;43(13):1767.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose:Evaluate function of rod cells in patients with Smith Lemli Opitz syndrome (SLOS), a rare genetic disorder caused by an inborn error of cholesterol biosynthesis resulting in cholesterol deficiency and accumulation of 7-dehydrocholesterol (7-DHC). This metabolic error is known to alter membranes in blood cells and skin. Methods:Genotyped SLO patients (n=14; median age 7 years) with normal serum vitamin A levels had rod mediated ERG responses to a 5-6 log unit range of full field stimuli recorded under anesthesia. We derived the parameters of activation and deactivation from the a-wave. Specifically, activation was represented by S, reflecting the kinetics of the early phase of the rod response and Rmp3, the saturated amplitude of the response. A paired flash paradigm was used to reconstruct the time course of the rod's response to a +3.6 log scotopic td sec flash; deactivation was represented by t50, the time at which recovery was 50% of the maximum response. One patient with longstanding Mellaril retinopathy had marked attenuation of ERG responses and was excluded from analysis. Results:The kinetics of activation were significantly (t=-6.3; p<0.01) slower (6.5, SD= 1.9 isoms-1sec-2 vs. 10.2, SD= 1.6 isoms-1sec-2) in SLOS patients (n=13) than in normal controls (n=25). The saturated amplitude did not differ significantly between SLOS and controls. The recovery of the rod response, represented by t50, was significantly slower (11.3, SD=3.4 sec vs 3.0, SD= 1 sec) SLOS than controls. Conclusion:Significant slowing of processes in the rod cell membranes is common in SLOS. This may be due to altered structure of cholesterol deficient membranes and/or accumulation of 7-DHC.
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