Plasma lipid abnormalities in retinitis pigmentosa and related conditions

Plasma samples obtained from 69 fasting retinitis pigmentosa (RP) patients and 110 controls were assayed for cholesterol, triglycerides, lipoproteins, and fatty acids. It was found that many RP patients were hyperlipidaemic compared to their spouses and siblings, as well as compared to unrelated controls. This hyperlipideaemia was particularly severe in men over 35 years of age, and in hemizygotes in X-linked families. In contrast, hypocholesterolaemia was observed in albipunctate retinal dystrophy. Plasma fatty acid titres were, in general, similar in RP patients and controls; however, patients in three families (two X-linked, one autosomal dominant) showed a significant reduction in docosahexaenoic acid (C22:6) compared to their unaffected relatives. These various plasma lipid abnormalities may reflect disorders in lipid metabolism which also may lead to retinal dystrophy.