The membrane lipid and fatty acid composition of erythrocyte ghosts from three patients with paramyotonia congenita

Abstract

The membrane lipid and fatty acid composition of red blood cell ghosts from three paramyotonia patients was investigated. Cholesterol and total phospholipid contents were not different from the controls, but the sphingomyelin content was reduced, and this was compensated for by an increase in phosphatidylcholine. Thus, the molar ratios of phosphatidylcholine/sphingomyelin and phophatidylcholine/phosphatidylethanolamine were greater than normal. The saturated fatty acids in the total phospholipids were increased so that the ratio of saturated/unsaturated fatty acids was 1.4-1.6 versus 1.1-1.2 in the controls. The polyunsaturated fatty acids comprised only 22-26% of the fatty acids versus 31-32% in controls. The reduction in content of unsaturated fatty acids concerned all phospholipid classes in one patient and only the choline phospholipids in the tow other patients who were related to each other. The pattern of the fatty acids in the C2-position of the glycerophospholipids reflected the finding in the total phospholipids. Thus, an alteration of the activity of the acyl-CoA: 1-mono-acylphosphoglyceride-acyltransferase seems unlikely. The results support the notion of a generalized membrane defect in paramyotonia congenita, although the degree of abnormality in the fatty acid pattern was not correlated with the severity of the clinical symptoms.