Association of FCRL3 Gene Polymorphisms with IgA Nephropathy in a Chinese Han Population

Genome-Wide Association Studies for Albuminuria of Nondiabetic Taiwanese Population

INTRODUCTION

Chronic kidney disease, which is defined by a reduced estimated glomerular filtration rate and albuminuria, imposes a large health burden worldwide. Ethnicity-specific associations are frequently observed in genome-wide association studies (GWAS). This study conducts a GWAS of albuminuria in the nondiabetic population of Taiwan.

METHODS

Nondiabetic individuals aged 30-70 years without a history of cancer were enrolled from the Taiwan Biobank. A total of 6,768 subjects were subjected to a spot urine examination. After quality control using PLINK and imputation using SHAPEIT and IMPUTE2, a total of 3,638,350 single-nucleotide polymorphisms (SNPs) remained for testing. SNPs with a minor allele frequency of less than 0.1% were excluded. Linear regression was used to determine the relationship between SNPs and log urine albumin-to-creatinine ratio.

RESULTS

Six suggestive loci are identified in or near the FCRL3 (p = 2.56 × 10-6), TMEM161 (p = 4.43 × 10-6), EFCAB1 (p = 2.03 × 10-6), ELMOD1 (p = 2.97 × 10-6), RYR3 (p = 1.34 × 10-6), and PIEZO2 (p = 2.19 × 10-7). Genetic variants in the FCRL3 gene that encode a secretory IgA receptor are found to be associated with IgA nephropathy, which can manifest as proteinuria. The PIEZO2 gene encodes a sensor for mechanical forces in mesangial cells and renin-producing cells. Five SNPs with a p-value between 5 × 10-6 and 5 × 10-5 are also identified in five genes that may have a biological role in the development of albuminuria.

CONCLUSION

Five new loci and one known suggestive locus for albuminuria are identified in the nondiabetic Taiwanese population.

Noncoding RNAs associated with IgA nephropathy

IgA nephropathy (IgAN) is one of the most common glomerulonephritides. The disease is characterized by haematuria, proteinuria, deposition of galactose-deficient IgA1 in the glomerular mesangium and mesangial hypercellularity, further leading to extracellular matrix expansion. Kidney biopsy is the gold standard for IgAN diagnosis. Due to the invasiveness of renal biopsy, there is an unmet need for noninvasive biomarkers to diagnose and estimate the severity of IgAN. Understanding the role of RNA molecules as genetic markers to target diseases may allow developing therapeutic and diagnostic markers. In this review we have focused on intrarenal, extrarenal and extracellular noncoding RNAs involved in the progression of IgAN. This narrative review summarizes the pathogenesis of IgAN along with the correlation of noncoding RNA molecules such as microRNAs, small interfering RNAs, circular RNAs and long non-coding RNAs that play an important role in regulating gene expression, and that represent another type of regulation affecting the expression of specific glycosyltranferases, a key element contributing to the development of IgAN.

MIR17HG genetic variations affect the susceptibility of IgA nephropathy in Chinese Han people

BACKGROUND

Immunoglobulin A nephropathy (IgAN) is the most common primary glomerular disease worldwide. It accounts for approximately 30 ~ 40% of glomerular diseases in China. However, the exact pathogenesis of IgAN is not well established. This study aimed to explore the association between MIR17HG polymorphisms and IgAN susceptibility.

METHODS

Six single nucleotide polymorphisms (SNPs) of MIR17HG were genotyped in 417 patients with IgAN and 424 healthy controls. The association analysis was conducted by logistic regression adjusted for age and gender in multiple genetic models and different subgroups.

RESULTS

Our results revealed that rs72640334 and rs1428 increased the susceptibility to IgAN in total populations (p < 0.05). The stratification analysis by age indicated that rs72640334 enhanced the risk of IgAN people older than 35 years, while rs7318578 played a protective role in the development of IgAN patients aged >35 years (p < 0.05). In addition, MIR17HG-rs72640334 could facilitate the occurrence of IgAN in females (p < 0.05). In Lee's grade III-Vsubgroup, rs72640334 and rs7336610 have an increasing effect on IgAN risk, while rs7318578 has a decreasing effect on IgAN susceptibility (p < 0.05).

CONCLUSIONS

Our findings suggested that MIR17HG genetic polymorphisms were correlated with IgAN susceptibility. It provided new evidence for the potential molecular mechanism of IgAN and may serve as a new biomarker for the treatment and early diagnosis of IgAN.

The Non-Coding RNA Landscape in IgA Nephropathy-Where Are We in 2021?

IgA nephropathy (IgAN) is the most commonly diagnosed primary glomerulonephritis worldwide. It is a slow progressing disease with approximately 30% of cases reaching end-stage kidney disease within 20 years of diagnosis. It is currently only diagnosed by an invasive biopsy and treatment options are limited. However, the current surge in interest in RNA interference is opening up new horizons for the use of this new technology in the field of IgAN management. A greater understanding of the fundamentals of RNA interference offers exciting possibilities both for biomarker discovery and, more importantly, for novel therapeutic approaches to target key pathogenic pathways in IgAN. This review aims to summarise the RNA interference literature in the context of microRNAs and their association with the multifaceted aspects of IgA nephropathy.

Expression profile of Fc receptor-like molecules in patients with IgA nephropathy

BACKGROUND

Fc receptor-like (FCRL) molecules were considered to play a role in the pathogenesis of certain autoimmune diseases. Nonetheless, the clinical significance of FCRLs in IgA nephropathy (IgAN) remains unclear.

OBJECTIVE

This study is aimed at investigating the expression levels of FCRLs molecules in IgAN patients and determining its relevance to disease activity.

METHODS

The mRNA expression levels of FCRLs were determined in peripheral blood mononuclear cells (PBMCs) of 42 IgAN patients and 48 healthy controls by quantitative real-time PCR (qRT-PCR). FCRLs proteins expression in B cells of 25 IgAN patients, 14 patients with non-IgAN glomerulonephritis, and 29 healthy controls were detected by Flow cytometry. The Spearman correlation test was used to assess the correlation of FCRLs expression with clinical parameters of IgAN patients.

RESULTS

Our results indicated significant down-regulation of FCRL2 and FCRL3 mRNA levels in IgAN patients compared to healthy subjects. Surface protein expression of FCRLs molecules confirmed the qRT-PCR results. But FCRL2 and FCRL3 protein levels did not correlate with clinicopathologic phenotypes of IgAN patients. However, we found a significant positively correlation of FCRL2 and FCRL3 mRNA expression with the core 1 β1,3-galactosyltransferase (C1GALT1) and its molecular chaperone (Cosmc) mRNA levels in IgAN patients.

CONCLUSIONS

FCRL2 and FCRL3 expression levels in IgAN patients are significantly decreased and correlated with CIGALT1 and Cosmc mRNA expression.

Genetic variants of the MIR31HG gene are related to a risk of IgA nephropathy

IgA nephropathy (IgAN) is the most common primary glomerulonephritis worldwide. Previous studies reveal that genetic factors play a crucial role in IgAN progression. This study was conducted to investigate the association between MIR31HG variants and IgAN risk. A total of 836 subjects were recruited to detect the relationship of MIR31HG variants with IgAN susceptibility. Odds ratios (OR) and 95% confidence intervals (CI) were computed to evaluate the associations. Multifactor dimensionality reduction was performed to analyze the SNP-SNP interaction with IgAN risk. Our study showed that rs1332184 and rs55683539 significantly related to an increased risk of IgAN (OR 1.34, p = 0.041; OR 1.39, p = 0.025). Stratified analyses indicated rs72703442, rs55683539, and rs10965064 exhibited strongly enhanced risk of IgAN in age ≤ 35 years (OR 1.55, p = 0.023; OR 1.60, p = 0.012; OR 1.46, p = 0.037). Besides, we found rs1332184, rs55683539 and rs2181559 significantly increased the susceptibility of IgAN in males (OR 1.71, p = 0.003; OR 1.44, p = 0.042; OR 1.60, p = 0.010). We also observed that rs1332184 could enhance IgAN risk for Lee's grade ≥ III (OR 1.39, p = 0.045). Rs55683539 significantly increased a risk of IgAN (OR 1.58, p = 0.027), while rs2025327 had a lower risk of IgAN in Lee's grade < III (OR 0.46, p = 0.007). Interestingly, we found rs72703442 polymorphism was related to hemoglobin (p = 0.043), and rs10965064 was associated with Urine red blood cell (p = 0.040). Our study proposed that MIR31HG polymorphisms associate with susceptibility to IgAN in Chinese population.