Lipoprotein glomerulopathy: first report in a Chinese male

Lipoprotein Glomerulopathy, First Case Report from Canada

Lipoprotein glomerulopathy (LPG) is caused by a mutation in the apolipoprotein E gene (APOE) gene and is characterized by lipoprotein thrombi in glomerular capillaries. Here, we describe a case of LPG, the first to be reported from Canada and the first case of LPG in North America to be associated with the APOE Tokyo/Maebashi mutation (p.Leu162_Lys164del, traditional nomenclature 142_144del). A 49-year-old man of Chinese descent with a previous diagnosis of dyslipidemia and a new diagnosis of hypertension was found to have proteinuria on routine urinalysis. Renal biopsy showed markedly dilated glomerular capillaries filled with pale staining mesh-like material that stained positive for Oil-Red-O, consistent with lipoprotein thrombi. APOE gene sequencing confirmed the diagnosis of LPG. The patient was treated with fenofibrate and perindopril. His lipid profile normalized and proteinuria dropped to minimal levels. Repeat renal biopsy 2 years after the first showed resolution of lipoprotein thrombi but with rare residual granular densities by electron microscopy consistent with lipoprotein in the subendothelial space, supporting the hypothesis that this subendothelial material contains precursors to lipoprotein thrombi.

An Updated Review and Meta Analysis of Lipoprotein Glomerulopathy

More than 200 cases of lipoprotein glomerulopathy (LPG) have been reported since it was first discovered 30 years ago. Although relatively rare, LPG is clinically an important cause of nephrotic syndrome and end-stage renal disease. Mutations in the APOE gene are the leading cause of LPG. APOE mutations are an important determinant of lipid profiles and cardiovascular health in the population and can precipitate dysbetalipoproteinemia and glomerulopathy. Apolipoprotein E-related glomerular disorders include APOE2 homozygote glomerulopathy and LPG with heterozygous APOE mutations. In recent years, there has been a rapid increase in the number of LPG case reports and some progress in research into the mechanism and animal models of LPG. We consequently need to update recent epidemiological studies and the molecular mechanisms of LPG. This endeavor may help us not only to diagnose and treat LPG in a more personized manner but also to better understand the potential relationship between lipids and the kidney.

Case Report: A Pediatric Case of Lipoprotein Glomerulopathy in China and Literature Review

Background: Lipoprotein glomerulopathy is a rare kidney disease characterized by lipoprotein thrombi in the glomerulus. Here, we report a case of lipoprotein glomerulopathy in a Chinese pediatric patient. Furthermore, we summarized the clinical features and genetic characteristics of lipoprotein glomerulopathy in China. Case Presentation: An 11-year-old Chinese girl presented with nephrotic syndrome with anemia (98 g/L). After excluding secondary causes, primary nephrotic syndrome was considered. Treatment with prednisone (60 mg/day) did not improve her condition. Renal biopsy showed marked dilation of the capillary lumen with lipoprotein thrombi and positive oil red O staining. Genetic testing revealed the genetic variant c.127C > T (p.R43C), known as the Kyoto mutation of the APOE gene. These findings are consistent with the diagnosis of lipoprotein glomerulopathy. Prednisone was gradually tapered and captopril was initiated. A 2-year follow-up revealed elevated urine protein and serum creatinine levels. We also reviewed 17 pediatric and 156 adult cases of lipoprotein glomerulopathy reported in China from the year of creation to 2021. The most common clinical features were edema, hematuria, hypertriglyceridemia, and increased serum apoE levels. Extra-renal manifestations included anemia, splenomegaly, and cardiac lipoprotein deposition. Conclusion: APOE Kyoto is the most common mutation in patients with lipoprotein glomerulopathy. In China, homozygosity for E3 (E3/3) is the most common isoform.

A case of nephrotic syndrome showing contemporary presence of apolipoprotein E2 homozygote glomerulopathy and membranous nephropathy-like findings modified by apolipoprotein E Toyonaka

A 79-year-old man was admitted to our hospital for proteinuria due to nephrotic syndrome. Renal biopsy revealed focal sclerosis and foam cell infiltration in the glomerulus. In addition, electron microscopic findings (EM) revealed peculiar electron-dense deposits (EDDs) in both sides of the glomerular basement membrane. Although subepithelial deposits had spike formation highly resembling those seen in membranous nephropathy (MN), immunoglobulins and complements were not identified by immunofluorescence study, and microbubbles appeared in high magnification of EM different from the immune disease. The analysis of apolipoprotein (Apo) E showed an elevated concentration of plasma ApoE. The phenotype, genotype, and DNA sequence studies revealed homozygous ApoE2/2 and a novel missense mutation called ApoE Toyonaka (Ser197Cys). This case may confirm the independent responsibility of ApoE2/2 and ApoE Toyonaka for ApoE2 homozygote glomerulopathy and MN-like EDD findings, respectively.

Membranous Nephropathy-Like Apolipoprotein E Deposition Disease with Apolipoprotein E Toyonaka (Ser197Cys) and a Homozygous Apolipoprotein E2/2

A 20-year-old female student underwent renal biopsy because of chance proteinuria and hematuria. Histological study revealed a membranous nephropathy-like appearance by light microscopy. But immunoglobulins and complements were negative in the glomerulus by immunofluorescence study. On the other hand, plasma apolipoprotein E (ApoE) concentration was elevated to more than 2 times the normal range, and the phenotype, genotype, and DNA sequence studies of her ApoE showed homozygous ApoE2/2 and a heterozygous novel missense mutation called ApoE Toyonaka (Ser197Cys). Detailed immunohistochemical studies found that the dense deposits in subepithelial, subendothelial, and mesangial areas contained ApoE. Tandem mass spectrometry also proved a large amount of ApoE in the glomerulus. These findings suggest that ApoE Toyonaka with a homozygous ApoE2/2 may cause a new form of ApoE-related glomerular disease resembling membranous nephropathy.

Metabolism, energetics, and lipid biology in the podocyte - cellular cholesterol-mediated glomerular injury

Chronic kidney disease (CKD) is associated with a high risk of death. Dyslipidemia is commonly observed in patients with CKD and is accompanied by a decrease in plasma high-density lipoprotein, and an increase in plasma triglyceride-rich lipoproteins and oxidized lipids. The observation that statins may decrease albuminuria but do not stop the progression of CKD indicates that pathways other than the cholesterol synthesis contribute to cholesterol accumulation in the kidneys of patients with CKD. Recently, it has become clear that increased lipid influx and impaired reverse cholesterol transport can promote glomerulosclerosis, and tubulointerstitial damage. Lipid-rafts are cholesterol-rich membrane domains with important functions in regulating membrane fluidity, membrane protein trafficking, and in the assembly of signaling molecules. In podocytes, which are specialized cells of the glomerulus, they contribute to the spatial organization of the slit diaphragm (SD) under physiological and pathological conditions. The discovery that podocyte-specific proteins such as podocin can bind and recruit cholesterol contributing to the formation of the SD underlines the importance of cholesterol homeostasis in podocytes and suggests cholesterol as an important regulator in the development of proteinuric kidney disease. Cellular cholesterol accumulation due to increased synthesis, influx, or decreased efflux is an emerging concept in podocyte biology. This review will focus on the role of cellular cholesterol accumulation in the pathogenesis of kidney diseases with a focus on glomerular diseases.

Lipoprotein glomerulopathy

PURPOSE OF REVIEW

Lipoprotein glomerulopathy is a rare disorder characterized by proteinuria, renal insufficiency and disturbances in lipoprotein metabolism closely related to those observed in type III hyperlipidemia. Rare mutations in apolipoprotein E (apoE) gene may contribute to the pathogenesis of the disease. This article reviews the clinical and laboratory features of lipoprotein glomerulopathy, discusses the mechanisms that may be implicated in its pathogenesis and summarizes the currently available therapeutic options.

RECENT FINDINGS

During the past years two new apoE gene mutations were described in Caucasian patients, apoE Modena (Arg150→Cys) and apoE Las Vegas (Ala152→Asp), a finding indicating that the disease may be more common in white populations than initially thought. Results from case studies suggest that fibrates improve renal pathology and may result in the complete clinical remission of the disease. LDL-apheresis or immunoadsorption onto staphylococcal protein A may also have a role in refractory cases.

SUMMARY

Lipid glomerulopathy is a rare, poorly understood disorder with potentially detrimental consequences. The determination of the effects of apoE mutations on the structural and functional characteristics of the mature protein may provide new insights in the pathogenesis of the disease. Meanwhile, intensive lipid-lowering may reduce proteinuria and preserve renal function in this patient group.

A new apolipoprotein E mutation, apoE Las Vegas, in a European-American with lipoprotein glomerulopathy

Lipoprotein glomerulopathy is a rare disease diagnosed by unique histopathologic findings of glomerular capillary dilatation by lipoprotein thrombi. The disease is caused by mutations in apoE, the gene that encodes apolipoprotein E. To date, <80 cases have been reported in the medical literature, nearly all of which are from Japan or China. Only five cases from the United States have previously been reported, of which three patients were of European ancestry. Here, we present the fourth case of lipoprotein glomerulopathy in a European-American man. Whereas prior European-American patients with lipoprotein glomerulopathy were found to have the previously reported apoE Kyoto genotype, the patient presented here was found to have a novel mutation that we have named apoE Las Vegas.

A rare case of lipoprotein glomerulopathy in a white man: an emerging entity in Asia, rare in the white population

Lipoprotein glomerulopathy is a rare entity that predominantly affects the Asian population, mainly the Japanese and Chinese. Lipoprotein glomerulopathy is clinically characterized by proteinuria and progression to renal failure and is caused by glomerular lipoprotein thrombi formation in association with increased levels of serum apolipoprotein E. The disease has a male predominance and can affect virtually any age group. We describe the third reported case, to our knowledge, of lipoprotein glomerulopathy to affect a white patient.

Improvement of nephrotic syndrome by intensive lipid-lowering therapy in a patient with lipoprotein glomerulopathy

Lipoprotein glomerulopathy (LPG) is a rare hereditary disease characterized by the accumulation of much thrombi material consisting of lipoproteins at the glomerular capillary lumen. Most patients show nephrotic syndrome; nearly half progress to chronic renal failure. Intensive therapy with lipid-lowering agents reportedly engenders clinical remission with histological resolution. We report the case of a 14-year-old Japanese female patient who had been in a nephrotic condition with hematuria from 4 years old and who had been diagnosed based on pathological and molecular examination at 7 years old. We initially treated the patient with probucol, enalapril (angiotensin-converting enzyme inhibitor: ACEI), and dipyridamole from age 7, but achieved no improvement in her nephrotic status. Subsequently, we replaced probucol with bezafibrate at age 11 and added atorvastatin calcium hydrate and valsartan (angiotensin II receptor blocker: ARB) the following year. The next 3 years' treatment improved her nephrotic status, decreased serum apolipoprotein E, and markedly decreased intraglomerular lipoprotein thrombi. Early and intensive therapy with antilipidemic drugs combined with ACEI and ARB is inferred to be effective for LPG.

Lipoprotein glomerulopathy-like disease in a patient with type III hyperlipoproteinemia due to apolipoprotein E2 (Arg158 Cys)/3 heterozygosity

A 77-year-old woman developed nephrotic syndrome associated with type III hyperlipoproteinemia (III HLP) and increased apolipoprotein E (apo E). Apo E analysis disclosed E2/E3 heterozygosity in phenotypic and genotypic expressions, without any other mutations. A renal biopsy showed intraluminal and subendothelial thrombus-like deposits in the dilated capillary loops of the glomerulus that stained positive for lipids and apo E. Electron microscopy revealed tiny granular particles in the capillary lumina, as well as between the glomerular basement membrane and the endothelial cells. It was therefore concluded that III HLP associated with apo E2/E3 heterozygosity could induce lipoprotein glomerulopathy-like disease and nephrotic syndrome.

Lipoprotein glomerulopathy: a new apolipoprotein E mutation with enhanced glomerular binding

We describe a case of lipoprotein glomerulopathy, the second ever reported from the United States, in a Mexican man with a hitherto undescribed mutation in the apolipoprotein E gene (substitution of proline for arginine at position 147 [Arg147Pro]). In this patient, glomerular basement membranes showed double contours and circumferential mesangial extensions, suggesting that deposition of lipids could be injurious to endothelial cells. Immunofluorescence staining of thrombi was positive for apolipoprotein E and B. To study the reason for lipid deposition in glomeruli, we incubated normal human kidney sections with serum from the patient and a healthy control. Apolipoprotein E from the patient's serum showed binding to the glomerular capillary wall, but the control did not, suggesting enhanced binding of the mutated apolipoprotein E to glomerular capillaries. Apolipoprotein E genotyping by means of restriction endonuclease digestion of polymerase chain reaction-amplified genomic DNA showed it to be of the wild-type E3/E3.

Impact of Lipoprotein Glomerulopathy on the Relationship Between Lipids and Renal Diseases

Lipoprotein glomerulopathy (LPG) is a unique entity of renal lipidosis characterized by peculiar histopathologic characteristics of lipoprotein thrombi and an abnormal plasma lipoprotein profile resembling type III hyperlipoproteinemia, with a marked increase in serum apolipoprotein E (apoE) concentrations. At present, 65 cases have been reported worldwide, although most patients are found in Japan and east Asian countries. Recently, we identified 4 types of novel apoE mutations associated with LPG. In particular, a mutation designated apoE Sendai, in which arginine 145 is substituted with proline, occurs in the majority of Japanese patients. The virus-mediated transduction of apoE Sendai resulting in the development of LPG in apoE-deficient mice confirms the etiologic role of apoE mutation in LPG. Conversely, experimental graft-versus-host disease induced in Fc receptor gamma-chain-deficient mice showed LPG-like lesions in glomeruli without apoE mutations. Considered together, we believe that intrinsic factors in the kidney also contribute to the induction of LPG. Today, apoE and related lipid abnormalities are reported to have an important role in the development of various renal diseases, eg, diabetic nephropathy and immunoglobulin A nephropathy. In this article, we review clinical and histopathologic features of LPG, describe the etiologic role of apoE variants and intrinsic renal factors, and discuss the impact of LPG on mechanisms of other renal diseases.

Apolipoprotein E and renal disease

Apolipoprotein E (ApoE) is a major constituent of plasma lipoproteins with many biological actions of great significance. Beyond the known influence of ApoE polymorphisms on serum lipid profile, the pathogenesis of atherosclerosis, and the development of neurodegenerative disorders, ApoE also has a major role in the pathogenesis and progression of a variety of renal diseases, as well as in the atherosclerotic complications associated with them. Briefly, the polymorphisms of ApoE are major determinants of plasma lipid levels in uremic patients. They may affect the risk for cardiovascular disease in this population, predispose to the development of diabetic nephropathy, influence the severity of certain glomerulopathies, and regulate mesangial and glomerular functions locally in the kidney microenvironment. Finally, certain mutations of the ApoE gene are associated with a recently described nephropathy, termed lipoprotein glomerulopathy.

Disappearance of intraglomerular lipoprotein thrombi and marked improvement of nephrotic syndrome by bezafibrate treatment in a patient with lipoprotein glomerulopathy

Lipoprotein glomerulopathy (LPG) is a hereditary disorder characterized by intraglomerular lipoprotein thrombi and increased serum apolipoprotein (apo) E. Patients with LPG usually manifest with nephrotic syndrome, and some progress to renal failure; however, no effective therapeutic regimen has been established for this disease. We experienced a patient with LPG for whom bezafibrate treatment was very effective. This 30-year-old Japanese woman had nephrotic syndrome and type III hyperlipoproteinemia. Renal biopsy showed markedly dilated capillary lumina containing massive lipoprotein thrombi. Plasma apo E concentration was elevated to twice that of normal controls. She was proved to be a heterozygote of apo E2 Kyoto (Arg25Cys). After 2 years treatment with bezafibrate (400 mg/day), her plasma albumin gradually increased from 2.1 to 4.0 mg/dl, and intraglomerular lipoprotein thrombi disappeared almost completely. Bezafibrate decreased plasma apo E and dramatically increased high density lipoprotein (HDL)-cholesterol. The decrease in apo E was observed mainly in the pre-beta-fraction, not in the alpha fraction. Lipidological analyses of our patient suggest that the origin her lipoprotein thrombi may be mainly from pre-beta-lipoproteins and that HDL might be involved in resolving lipoprotein thrombi. Our case suggests that administration of fibrates such as bezafibrate may be a novel therapeutic strategy for resolving intraglomerular thrombi and improving nephrotic syndrome in patients with LPG.

Etiological significance of apolipoprotein E mutations in lipoprotein glomerulopathy

Lipoprotein glomerulopathy (LPG) is a newly recognized renal disease characterized by thrombus-like lipoproteins in the glomerular capillaries and abnormal lipoprotein profiles similar to those in type III hyperlipoproteinemia. Recently, these conditions have been shown to be associated with some apolipoprotein E (apoE) mutations. We found an apoE mutation (designated apoE-Sendai) that substitutes arginine 145 with proline. This mutation occurs most frequently in Japanese patients with LPG. To elucidate the etiological role of this mutation in the apoE gene, we established an experimental model for LPG by transducing apoE-Sendai in apoE knockout mice with the use of an adenovirus vector. Based on the findings in patients with LPG and its animal model, we suggest that the glomerular lesions are not only caused by hyperlipidemia, but also by in situ interaction between lipoprotein-containing mutant apoE with the glomerulus. In this review, we outline the clinical features of LPG and discuss the relationship between apoE mutations and LPG.

Novel glomerular lipoprotein deposits associated with apolipoprotein E2 homozygosity

BACKGROUND

Hyperlipoproteinemia is occasionally associated with severe glomerular injury caused by abnormal accumulation of lipid in glomeruli, which occurs in conditions such as lipoprotein glomerulopathy (LPG). This study investigates the cases of two siblings with homozygous apolipoprotein (apo) E2 who show unique histologic features, massive proteinuria, and dysbetalipoproteinemia.

METHODS

Histologic studies were performed using renal biopsy specimens. Plasma lipoproteins were extensively characterized. The exons of the apo E genes were sequenced to avoid missing any mutations.

RESULTS

Histologically, the siblings' condition resembled LPG by light microscopy studies. Electron microscopy studies revealed large lipoid deposits in the paramesangium, subendothelium, and subepithelium of the glomeruli, which were different from LPG in terms of not forming the layered structure resembling a fingerprint even in large lipoprotein thrombi, and mesangial foam cells. Immunohistochemically, the lipoid deposits contained apo E and apo B. These patients did not have either diabetic nephropathy or other known forms of glomerulonephritis. The sequence of exons of the apo E genes revealed homozygosity for apo E2 in both cases.

CONCLUSION

The extensive lipoprotein deposition in glomeruli, which resembles LPG, can also occur in apo E2 homozygous individuals, but in a distinct fashion. Because the two cases were siblings, they may have other shared alleles, in addition to the apo E2 allele, that negatively affect processing of lipoproteins and lead to abnormal accumulation of lipoprotein deposits in glomeruli.

Diminished LDL receptor and high heparin binding of apolipoprotein E2 Sendai associated with lipoprotein glomerulopathy

Variants of apolipoprotein E (apoE) have been linked to lipoprotein glomerulopathy, a new glomerular disease characterized by the deposition of lipoproteins in mesangial capillaries. One third of affected patients are heterozygous for apoE2 Sendai (Arg(145) Pro). Variants of apoE can also produce type III hyperlipoproteinemia (HLP). Recessive type III HLP is caused by apoE2 (Arg(158) Cys), a mutant with diminished low-density lipoprotein (LDL) receptor binding but halfnormal heparin binding. Dominant type III HLP is caused by mutations that markedly alter heparin binding but modestly reduce receptor binding. This study examined whether apoE2 Sendai (Arg(145) Pro) was functionally different from type III HLP-producing apoE variants by expressing apoE3, apoE2 (Arg(158) Cys), apoE1 (Arg(146) Glu), a dominant apoE variant, and apoE2 Sendai (Arg(145) Pro) in the baculovirus system. LDL receptor binding was studied using recombinant apoE complexed to phospholipid vesicles and to very lowdensity lipoprotein from a patient with familiar apoE deficiency. Compared with apoE3, receptor-binding activities of apoE2 (Arg(158) Cys), apoE1 (Arg(146) Glu), and apoE2 Sendai (Arg(145) Pro) all were less than 5%. Heparin-binding activities were 53%, 23%, and 66%, respectively, of apoE3. The distribution of apoE2 Sendai among the major plasma lipoprotein fractions was similar to that of apoE3 and apoE2 (Arg(158) Cys). ApoE2 Sendai (Arg(145) Pro) represents the only known mutation within the heparin-binding domain of apoE (residues 142 through 147), revealing diminished receptor binding and almost normal heparin binding. These unique characteristics of apoE2 Sendai (Arg(145) Pro) may relate to the development of lipoprotein glomerulopathy.

A novel apolipoprotein E mutation, E2 (Arg25Cys), in lipoprotein glomerulopathy

BACKGROUND

Lipoprotein glomerulopathy (LPG) is characterized by intraglomerular lipoprotein thrombosis and high plasma concentrations of apolipoprotein (apo) E. An apo E variant, apo E2 (Arg145Pro) Sendai, was recently identified in three patients with LPG. We detected a novel point mutation in the apo E gene in a patient with LPG, and we characterized the mutant apo E.

METHODS

The propositus was a 32-year-old male patient on maintenance hemodialysis because of LPG. The mutation was detected by sequencing of genomic DNA from the patient and was confirmed by restriction fragment length polymorphism (RFLP) with Aor51HI. Recombinant apo E2 (Arg25Cys) Kyoto and normal apo E3 were expressed from COS-1 cells. Low-density lipoprotein (LDL) receptor-binding activities of the variants were determined in an in vitro competition assay.

RESULTS

The propositus had the apo E phenotype E2/E4, as determined by isoelectric focusing, and the genotype epsilon3/epsilon4, as determined by RFLP with HhaI. Sequence analysis of amplified DNA showed a C to T transition, changing the codon for residue 25 from arginine to cysteine. The proband was a heterozygous carrier for apo E2 (Arg25Cys) Kyoto. A family study showed that the mother was a heterozygous carrier of apo E2 Kyoto and had dysbetalipoproteinemia, but no LPG. The pathophysiological effect of this mutation was investigated in vitro by binding studies of recombinant apo E2 Kyoto to LDL receptors on human fibroblasts. The ability of recombinant apo E2 Kyoto to displace LDL was reduced to 10% compared with recombinant apo E3.

CONCLUSIONS

Apo E2 (Arg25Cys) Kyoto is a novel mutation of apo E that is etiologically related to LPG. However, our case indicates that the development of LPG may involve other genetic or environmental factors. Furthermore, our data suggest that arginine-25 of apo E plays an important functional role by influencing the receptor-binding ability of apo E.

Lipoprotein glomerulopathy: significance of lipoprotein and ultrastructural features

BACKGROUND

Lipoprotein glomerulopathy (LPG) is a unique disease characterized by intraglomerular lipoprotein thrombi and type III hyperlipoproteinemia. Recently, we have demonstrated that LPG is associated with inherited apolipoprotein E (apoE) variants including apoE Sendai. On the other hand electron microscopy shows that intraglomerular lipoprotein thrombi consist of lipid granules of various sizes. To elucidate the relationship between the peculiar histology and abnormal lipid metabolism related to apoE Sendai, we studied lipoprotein profiles and ultrastructural features.

METHODS

The subjects were 11 patients with LPG. Four patients were nephrotic, and two others became nephrotic within six months following the biopsy. Eight patients underwent apoE gene analysis and showed apoE Sendai. The other three were presumed to have apoE Sendai because this mutation was demonstrated in their kindreds. Under electron microscopy, diameters of more than 1000 lipid granules were measured in several glomeruli, and a mean value was calculated in each case. Lipoprotein profiles were analyzed by the ultracentrifugation methods.

RESULTS

The mean diameter of intraglomerular lipid granules correlated inversely with the levels of plasma triglyceride (TG; rs = -0.73, P < 0.05), TG (rs = -0.77, P < 0.01) and cholesterol (Chol; rs = -0.75, P < 0.05) in very low-density lipoprotein (VLDL) fraction and TG in high-density lipoprotein (HDL) fraction (rs = -0.75, P < 0.05). The inverse correlation was also seen between the mean lipid diameter and TG/Chol ratios in whole plasma (rs = -0.80, P < 0.01) and in HDL (rs = -0.80, P < 0.01). In addition, the cases showing smaller lipid granules and higher TG/Chol ratios in plasma and in HDL were nephrotic or became nephrotic within six months.

CONCLUSION

These results suggest that the size of lipid granules in LPG may become smaller under the influence of hypertriglyceridemia and particularly elevated plasma VLDL and HDL-TG, which may lead to heavy proteinuria.

Genetics of lipoprotein disorders

The study of lipoprotein metabolism has led to major breakthroughs in the fields of cellular physiology, molecular genetics, and protein chemistry. These advances in basic science are reflected in medicine in the form of improved diagnostic methods and better therapeutic tools. Perhaps the greatest benefit is the improved ability to identify at an early stage patients who are at high risk for atherosclerosis, providing clinicians the opportunity to proceed swiftly with intensive lipid-lowering therapy for the prevention of cardiovascular complications. Recent clinical trials have shown that such an approach is not only cost-effective but saves lives while improving the quality of life. They also emphasize the important role physicians can have in prevention. More than half of patients with premature CAD have a familial form of dyslipoproteinemia. This review of the genetics of atherogenic lipoprotein disorders underscores the importance of identifying major genetic defects. It also stresses the need to take into account multifactorial etiologies and clustering of risk factors, as well as gene-gene and gene-environment interactions in assessing the atherogenic potential of a lipid transport disorder. Table 2 summarizes the key points in the diagnosis, clinical implications, and treatment of the major inherited atherogenic dyslipidemias.

Abnormal lipid metabolism and renal disorders

Abnormal renal diseases including nephrotic syndrome and chronic renal failure are associated with hyperlipidemia, significance of abnormal lipid metabolism has been thought to be limited in some inherited renal diseases. However, recent studies have postulated that glomerulosclerosis is induced by hyperlipidemia and is in common with atherosclerosis. This involvement is found in the progressive renal disorders, e.g., focal glomerular sclerosis, diabetic nephropathy and glycogen storage disease. Interaction between macrophages and mesangial cells may play an important role in such conditions. This evidence is supported by experimental models with hyperlipidemia. On the other hand, discovery and new hereditary metabolic disorders, such as type III hyperlipoproteinemia and lipoprotein glomerulopathy, shows that apolipoprotein (apo) E abnormalities are responsible for the glomerular lesions. Especially, lipoprotein glomerulopathy has specific features different from those of lipid-induced renal diseases. In this disease, apo E Sendai which results from new substitution (Arginine 145-->Proline) may induce intraglomerular lipoprotein thrombi characteristic of lipoprotein glomerulopathy.