The genetic architecture of membranous nephropathy and its potential to improve non-invasive diagnosis Jingyuan Xie et al. # Membranous Nephropathy (MN) is a rare autoimmune cause of kidney failure. Here we report a genome-wide association study (GWAS) for primary MN in 3,782 cases and 9,038 controls of East Asian and European ancestries. We discover two previously unreported loci, NFKB1

BackgroundSteroid-sensitive nephrotic syndrome (SSNS), the most common form of nephrotic syndrome in childhood, is considered an autoimmune disease with an established classic HLA association. However, the precise etiology of the disease is unclear. In other autoimmune diseases, the identification of loci outside the classic HLA region by genome-wide association studies (GWAS) has provided critical insights into disease pathogenesis. Previously conducted GWAS of SSNS have not identified non-HLA loci achieving genome-wide significance.MethodsIn an attempt to identify additional loci associated with SSNS, we conducted a GWAS of a large cohort of European ancestry comprising 422 ethnically homogeneous pediatric patients and 5642 ethnically matched controls.ResultsThe GWAS found three loci that achieved genome-wide significance, which explain approximately 14% of the genetic risk for SSNS. It confirmed the previously reported association with the HLA-DR/DQ region (lead single-nucleotide polymorphism [SNP] rs9273542, P=1.59×10−43; odds ratio [OR], 3.39; 95% confidence interval [95% CI], 2.86 to 4.03) and identified two additional loci outside the HLA region on chromosomes 4q13.3 and 6q22.1. The latter contains the calcium homeostasis modulator family member 6 gene CALHM6 (previously called FAM26F). CALHM6 is implicated in immune response modulation; the lead SNP (rs2637678, P=1.27×10−17; OR, 0.51; 95% CI, 0.44 to 0.60) exhibits strong expression quantitative trait loci effects, the risk allele being associated with lower lymphocytic expression of CALHM6.ConclusionsBecause CALHM6 is implicated in regulating the immune response to infection, this may provide an explanation for the typical triggering of SSNS onset by infections. Our results suggest that a genetically conferred risk of immune dysregulation may be a key component in the pathogenesis of SSNS.

1. A method for assessing cholecalciferol absorption in man is described. 2. The intestinal absorption of [3H]cholecalciferol was studied in 20 female geriatric patients, most of whom were vitamin D-depleted. 3. The plasma [3H]cholecalciferol response after oral ingestion was significantly lower than that of a group of younger female subjects. 4. The plasma response of labelled polar metabolites of cholecalciferol was also lower in the geriatric than in the younger group, suggesting that increased removal of label by conversion into more polar metabolites could not account for the reduced plasma [3H]cholecalciferol response. 5. There was no evidence that alteration in gastrointestinal motility could account for the different rate of appearance of the labelled vitamin in the plasma in the two groups. 6. It is suggested that there is a defect in intestinal absorption of cholecalciferol in the elderly.

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