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Research Article Free access | 10.1172/JCI107392
Thorndike Memorial Laboratory, Harvard Medical Unit, Boston City Hospital, Boston, Massachusetts 02118
Department of Medicine, Harvard Medical School, Boston, Massachusetts 02118
Find articles by Schreibman, P. in: JCI | PubMed | Google Scholar
Thorndike Memorial Laboratory, Harvard Medical Unit, Boston City Hospital, Boston, Massachusetts 02118
Department of Medicine, Harvard Medical School, Boston, Massachusetts 02118
Find articles by Arons, D. in: JCI | PubMed | Google Scholar
Thorndike Memorial Laboratory, Harvard Medical Unit, Boston City Hospital, Boston, Massachusetts 02118
Department of Medicine, Harvard Medical School, Boston, Massachusetts 02118
Find articles by Saudek, C. in: JCI | PubMed | Google Scholar
Thorndike Memorial Laboratory, Harvard Medical Unit, Boston City Hospital, Boston, Massachusetts 02118
Department of Medicine, Harvard Medical School, Boston, Massachusetts 02118
Find articles by Arky, R. in: JCI | PubMed | Google Scholar
Published August 1, 1973 - More info
A 5-yr old male proband and his sister have had hypertriglyceridemia and hepatosplenomegaly since birth. When studied on a metabolic ward, they demonstrated rapid decreases in serum triglycerides on 3 g fat/day diets. Oral glucose tolerance tests were normal. Postheparin lipolytic activity (PHLA) against chylomicrons was virtually absent in both children whereas the mother and a normolipemic sister had levels approximately 50% normal. However, all four had a normal PHLA against commercial triglyceride emulsion (Intralipid). Two unrelated children from different kindreds of typical type 1 hyperlipoproteinemia and two patients with acquired type V hyperlipoproteinemia had deficient PHLA against both substrates. No inhibitors of PHLA could be demonstrated in the proband's plasma, and his own PHLA could not be enhanced by either normal concentrated plasma or pooled d > 1.063 lipoprotein fraction. The proband's postheparin plasma required almost 20 times the normal chylomicron-triglyceride concentration to reach one-half maximal lipase velocity.
Both affected siblings showed heavy pre-beta lipoprotein electrophoretic bands plus chylomicrons in their fasting plasmas while ingesting a 33% carbohydrate, 30% fat diet. Incubation of their postheparin plasma with Sf > 400 chylomicrons in vitro produced a smaller Sf 20-400 “remnant” with pre-beta electrophoretic mobility that was not seen under the same conditions when normal postheparin plasma was used. Postheparin monoglyceridase and phospholipase activities were either normal or only moderately decreased when determined with appropriate artificial substrates. These data are consistent with either (a) a mutant gene producing a lipoprotein lipase with unusual substrate specificities or (b) an absolute deficiency of normal lipoprotein lipase with a compensatory increase in some other postheparin triglyceridase.
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