LIPOPROTEIN-LIPASE DEFICIENCY WITH PANCREATITIS IN MINK - BIOCHEMICAL-CHARACTERIZATION AND PATHOLOGY

A severe hyperlipemia in mink, with a pattern that suggested recessive inheritance, was observed at a farm in Norway. On a normal mink diet, affected animals had grossly elevated levels of plasma triglycerides which decreased towards normal on a low-fat diet. Normal minks had the main part of their plasma cholesterol in the HDL fraction. Affected m inks, although severely hypertriglyceridaemic, had almost normal level s of both LDL and HDL. Affected minks frequently had lipogranulomas in the mesentery and the pancreas. The lipogranulomatous tissue containe d spaces filled with an amorphous, sudanophilic substance with many fo amy macrophages in the fibrous tissue between the lesions. Separation of postheparin plasma on heparin-agarose revealed that the affected mi nks had no detectable lipoprotein lipase activity but normal activity of hepatic lipase. Both normal and affected minks had inactive lipopro tein lipase protein in pre- and post-heparin plasma. This protein, whi ch eluted before the active lipase from heparin-agarose, probably corr esponds to lipase monomers. The presence of lipoprotein lipase mass in the affected minks, but no activity, indicates that there might be a point mutation in the lipase gene. The minks provide a new animal mode l for studies on pancreatitis induced by hypertriglyceridemia and on l ipoprotein metabolism in the lipoprotein lipase-deficient state and sh ow features similar to those found in human hyperlipoproteinemia type I.