Familial Lecithin: Cholesterol Acyltransferase Deficiency Further Studies on Plasma Lipoproteins and Plasma Postheparin Lipase Activity of a Patient with Normal Renal Function

Abstract

Plasma lipoproteins and postheparin plasma were investigated in a patient with familial LCAT deficiency with normal renal function and without proteinuria. As revealed by gelfiltration the large molecular weight LDL₂ was not present, and myelin structures were not found in LDL₁ or LDL₂ when she was on her ordinary diet. After 60-65% fat diet for one week the large molecular LDL₂ was found, but only in low concentration. We have no explanation for the difference in the lipoprotein abnormalities of this patient and others with this disease. There is no major difference in the fat content in the ordinary diet of the Norwegian patients with familial LCAT deficiency, nor has our patient any clinical signs of malabsorption. Furthermore, there was no difference in lipoprotein lipase or hepatic lipase activity in postheparin plasma between our patient and others with the same disease. However, whereas hepatic lipase activity was within the reference values, lipoprotein lipase activity was rather low in all patients investigated. We suggest that impaired VLDL catabolism in plasma, because of LCAT deficiency and low lipoprotein lipase activity, may partly explain the low HDL concentration consistently found in patients with familial LCAT deficiency.

Key Words:

• familial lecithin: cholesterol acyltransferase deficiency
• large molecular weight low density lipoproteins
• lipoprotein lipase activity
• normal renal function