Advances in Pathogenesis of Idiopathic Membranous Nephropathy

Background

Membranous nephropathy (MN), a major cause of nephrotic syndrome, has attracted people's attention in recent years for its growing prevalence. It is the second or third leading cause of ESRD in patients with primary glomerulonephritis and is the leading glomerulopathy that recurs after kidney transplantation.

Summary

MN can be classified as idiopathic membranous nephropathy (IMN) and secondary MN. The discovery of the M-type phospholipase A2 receptor (PLA2R) and thrombospondin type-1 domain-containing 7A (THSD7A) provides the new diagnostic methods and treatment strategies for IMN on the molecular level. The study on single nucleotide polymorphism of IMN genes, such as the single M-type phospholipase A2 receptor 1 (PLA2R1) gene and human leukocyte antigen (HLA) gene, explains the pathogenesis of the disease from the perspective of genetics and conforms to the trend of the era of precision medicine.

Key Messages

This review focuses on advances in the pathogenesis of IMN, including molecular and genetic pathogenesis, as well as discussing the diagnostic and treatment guiding value brought by these new discoveries.

Non-diabetic end-stage renal disease in Saudis associated with polymorphism of MYH9 gene but not UMOD gene

The prevalence of risk factors of chronic kidney disease in Saudi Arabia has augmented an already serious public health problem, therefore, determination of genetic variants associated with the risk of the disease presents potential screening tools that help reducing the incidence rates and promote effective disease management.The aim of the present study is to determine the association of UMOD and MYH9 genetic variants with the risk of non-diabetic end-stage renal disease (ESRD) in the Saudi population.Two single nucleotide polymorphisms (SNP), rs12917707 in gene UMOD and rs4821480 in gene MYH9 were genotyped in 154 non-diabetic ESRD Saudi patients and 123 age-matched healthy controls using Primers and Polymerase chain reaction conditions (PCR), Sanger sequencing, and TaqMan Pre-designed SNP Genotyping Assay. The association of these genetic variants with the risk of the disease and other renal function determinants was assessed using statistical tools such as logistic regression and One-way Analysis of Variance tests.The genotypic frequency of the two SNPs showed no deviation from Hardy-Weinberg equilibrium, the minor allele frequency of UMOD SNP was 0.13 and MYH9 SNP was 0.08. rs4821480 in MYH9 was significantly associated with the risk of non-diabetic ESRD (OR = 3.86; 95%CI: 1.38-10.82, P value .010), while, rs12917707 showed lack of significant association with the disease, P value .380. and neither of the 2 SNPs showed any association with the renal function determinants, serum albumin, and alkaline phosphatase enzyme.

Genetic susceptibility to idiopathic membranous nephropathy in high-prevalence Area, Taiwan

Idiopathic membranous nephropathy (MN) is one common cause of idiopathic nephrotic syndrome in adults; 25% of MN patients proceed to end-stage renal disease. In adults, membranous nephropathy is a lead cause of nephrotic syndrome, with about 75% of the cases idiopathic. Secondary causes include autoimmune disease, infection, drugs and malignancy. Three hypotheses about pathogenesis have surfaced: preformed immune complex, in situ immune complex formation, and auto-antibody against podocyte membrane antigen. Pathogenesis does involve immune complex formation with later deposition in sub-epithelial sites, but definite mechanism is still unknown. Several genes were recently proven associated with primary membranous nephropathy in Taiwan: IL-6, NPHS1, TLR-4, TLR-9, STAT4, and MYH9 . These may provide a useful tool for diagnosis and prognosis. This article reviews epidemiology and lends new information on KIRREL2 (rs443186 and rs447707) polymorphisms as underlying causes of MN; polymorphisms revealed by this study warrant further investigation.