Lipoprotein glomerulopathy (LPG) is a renal disease characterized by thrombus-like lipoproteins in the glomerular capillaries and its abnormal lipoprotein profiles with marked elevation of apolipoprotein E (apoE). In this study, 15 Chinese patients with LPG were involed in exploring the association of the genetic variation and its plasma level in the pathogenesis of LPG.
A retrospective analysis of the clinical and pathological features was made in 15 patients with LPG. Plasma concentrations of apoE were measured with radial immunodiffusion assay. Genetic variations of apoE gene were detected using polymerase chain reaction and restriction fragment length polymorphism. Glomerular deposition of apoA, apoB and apoE in these patients were detected by immunofluorescence staining using monoclonal antibodies.
Biochemical profiles of lipids and lipoproteins revealed markedly elevated levels of triglyceride, apoB and apoE, but approximately normal levels of total cholesterol, apoA1 and lipoprotein(a) [Lp(a)], which resembled familial hypertriglyceridemia. Genetic analysis demonstrated that the genotype distribution of apoE were 7 cases with epsilon3/epsilon4, 4 cases with epsilon3/epsilon3 and 2 cases with epsilon2/epsilon3. The other 2 cases (a mother and her son) showed a same distinct band. The band pattern of later 2 cases was quite similar to the apoE variant of Tokyo type. The calculated allele frequency of epsilon 4 was relatively high in cases with LPG in comparison with that in the normal controls. We further divided the 13 patients into three groups according to their genotypes of apoE. Patients with the genotype of apoE epsilon2/epsilon3 showed a lower level of plasma apoE as compared to those with apoE epsilon3/epsilon4 (P < 0.05). The serum level of high-density lipoprotein (HDL) was the lowest in patients with the genotype of apoE epsilon3/epsilon4. No difference was found among the patients with different apoE genotype in the other clinical and pathological characteristics.
The genotype of apoE epsilon3/epsilon4 is the predominant one in Chinese patients with LPG. Patients with this genotype tend to have a higher plasma level of apoE and more severe lipid dysmetabolism. No correlation was found between the genotype of apoE and the clinical features in patients with LPG.