Lipoprotein lipase activity and common gene variants in severely hypertriglyceridemic patients with and without diabetes

OBJECTIVES: In severe type IV hypertriglyceridemia (triglyceride levels >10 g/l), it is yet unknown whether lipoprotein lipase (LPL) differs according to the presence or not of diabetes. METHODS: We compared LPL activity and the presence of four common variants in the LPL gene (Asp 9 Asn (exon 2), Gly 188 Glu (exon 5), Asn 291 Ser (exon 6) and Ser 447 Ter (exon 9)) in a group of 34 patients of whom 17 presented diabetes mellitus. RESULTS: Maximum triglyceride, cholesterol levels and distribution of apolipoprotein E phenotypes did not differ between the two subgroups. Mean post-heparin LPL activity was lower in non-diabetic compared to diabetic patients (9.74 vs. 12.98 micromol FFA/ml/h, p=0.033). Four patients were carrying a mutation in exon 9 (1 non-diabetic), 6 patients in exon 2 (4 non-diabetic) and 1 patient in the non-diabetic subgroup in exon 5. All mutations were at the heterozygous state. CONCLUSION: We found that LPL activity was lower in type IV hyperlipidemia in the absence of diabetes. Genetic defects in the LPL gene that could lead to this lower LPL tended to be more frequently observed in patients without diabetes. These data suggest that the pathomechanisms which contribute to severe type IV hyperlipidemia are different according to the presence or not of diabetes.