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

Lipoprotein glomerulopathy: a rare cause of steroid-resistant nephrotic syndrome in a child

Lipoprotein glomerulopathy (LPG) is a rare condition of renal lipidosis characterized by lipoprotein thrombi in glomeruli, an abnormal plasma lipoprotein profile, and a marked increase in serum apolipoprotein E (apo E) levels. It is a monogenic disorder with autosomal dominant inheritance and the average age of presentation is 32 years (4-69 years). It is rare in children. The presentation can be nephrotic syndrome, hematuria, or progressive renal failure. Here we report the first described case of LPG in an Indian 7.5-year-old boy who presented with steroid-resistant nephrotic syndrome with normal renal function. A renal biopsy was suggestive of lipoprotein glomerulopathy. The detection of a pathogenic variant in apo E, Kyoto type, by exome sequencing, confirmed the diagnosis of lipoprotein glomerulopathy. Complete response was achieved with Angiotensin-converting Enzyme inhibitor and fenofibrates.

The first case of lipoprotein glomerulopathy complicated with collagen type III glomerulopathy and literature review

Lipoprotein glomerulopathy (LPG) is a rare autosomal dominant kidney disease caused by pathogenic mutations in the APOE gene. Collagen type III glomerulopathy (CG) is a sporadic condition in adults characterized by abnormal accumulation of type III collagen in the subendothelial space and mesangium of the glomerulus. We report the first case of both LPG and CG in a 21-year-old male. A search of the literature found no confirmed reports of these two concomitant nephropathies. The patient presented with hypertension, proteinuria, hematuria and hyperlipidemia. Renal pathology showed lipid vacuoles in the enlarged glomerular capillary loops and type III collagen in the segmental mesangial area and on the inner side of the glomerular basement membrane by electron microscopy. Whole-exome sequencing revealed a heterozygous mutation (c.127C>T; p. Arg43Cys) in exon 3 of the APOE gene, known as the APOE-Kyoto of LPG. In addition, two heterozygous COL4A4 mutations (c.4715C>T in exon 47 and c.5065 T>C in exon 48) were observed, the first one was suspected pathogenic and the other one was uncertain significant. There is no special treatment for these diseases. The patient was treated with lipid-lowering agents, renin-angiotensin-aldosterone system inhibition and tripterygium glycosides. The patient received double-filtration plasmapheresis and immunoadsorption therapy when renal function deteriorated dramatically. Immunoadsorption was beneficial for this patient.

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.