Jingyuan Xie

IgA nephropathy (IgAN), major cause of kidney failure worldwide, is common in Asians, moderately prevalent in Europeans, and rare in Africans. It is not known if these differences represent variation in genes, environment, or ascertainment. In a recent GWAS, we localized five IgAN susceptibility loci on Chr.6p21 (HLA-DQB1/DRB1, PSMB9/TAP1, and DPA1/DPB2 loci), Chr.1q32 (CFHR3/R1 locus), and Chr.22q12 (HORMAD2 locus). These IgAN loci are associated with risk of other immune-mediated disorders such as type I diabetes, multiple sclerosis, or inflammatory bowel disease. We tested association of these loci in eight new independent cohorts of Asian, European, and African-American ancestry (N = 4,789), followed by meta-analysis with risk-score modeling in 12 cohorts (N = 10,755) and geospatial analysis in 85 world populations. Four susceptibility loci robustly replicated and all five loci were genome-wide significant in the combined cohort (P = 5×10⁻³²-3×10⁻¹⁰), with heterogeneity detected only at the PSMB9/TAP1 locus (I² = 0.60). Conditional analyses identified two new independent risk alleles within the HLA-DQB1/DRB1 locus, defining multiple risk and protective haplotypes within this interval. We also detected a significant genetic interaction, whereby the odds ratio for the HORMAD2 protective allele was reversed in homozygotes for a CFHR3/R1 deletion (P = 2.5×10⁻⁴). A seven-SNP genetic risk score, which explained 4.7% of overall IgAN risk, increased sharply with Eastward and Northward distance from Africa (r = 0.30, P = 3×10⁻¹²⁸). This model paralleled the known East-West gradient in disease risk. Moreover, the prediction of a South-North axis was confirmed by registry data showing that the prevalence of IgAN-attributable kidney failure is increased in Northern Europe, similar to multiple sclerosis and type I diabetes. Variation at IgAN susceptibility loci correlates with differences in disease prevalence among world populations. These findings inform genetic, biological, and epidemiological investigations of IgAN and permit cross-comparison with other complex traits that share genetic risk loci and geographic patterns with IgAN.

Abstract 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 (rs230540, OR = 1.25, P = 3.4 × 10 −12 ) and IRF4 (rs9405192, OR = 1.29, P = 1.4 × 10 −14 ), fine-map the PLA2R1 locus (rs17831251, OR = 2.25, P = 4.7 × 10 −103 ) and report ancestry-specific effects of three classical HLA alleles: DRB1*1501 in East Asians (OR = 3.81, P = 2.0 × 10 −49 ), DQA1*0501 in Europeans (OR = 2.88, P = 5.7 × 10 −93 ), and DRB1*0301 in both ethnicities (OR = 3.50, P = 9.2 × 10 −23 and OR = 3.39, P = 5.2 × 10 −82 , respectively). GWAS loci explain 32% of disease risk in East Asians and 25% in Europeans, and correctly re-classify 20–37% of the cases in validation cohorts that are antibody-negative by the serum anti-PLA2R ELISA diagnostic test. Our findings highlight an unusual genetic architecture of MN, with four loci and their interactions accounting for nearly one-third of the disease risk.

Anemia commonly aggravates the severity of respiratory diseases, whereas thus far, few studies have elucidated the impact of anemia on coronavirus disease 2019 (COVID-19). The aim of this study was to evaluate the clinical characteristics of patients with anemia, and to further explore the relationship between anemia and the severity of COVID-19. In this single-center, retrospective, observational study, a total of 222 confirmed patients admitted to Wuhan Ninth Hospital from 1 December 2019 to 20 March 2020 were recruited, including 79 patients with anemia and 143 patients without anemia. Clinical characteristics, laboratory findings, disease progression and prognosis were collected and analyzed. Risk factors associated with the severe illness in COVID-19 were established by univariable and multivariable logistic regression models. In our cohort, compared to patients without anemia, patients with anemia were more likely to have one or more comorbidities and severe COVID-19 illness. More patients demonstrated elevated levels of C-reactive protein (CRP), procalcitonin (PCT) and creatinine in anemia group. Levels of erythrocyte sedimentation rate, D-dimer, myoglobin, T-pro brain natriuretic peptide (T-pro-BNP) and urea nitrogen in patients with anemia were significantly higher than those without. In addition, the proportion of patients with dyspnea, elevated CRP, and PCT was positively associated with the severity of anemia. The odd ratio of anemia related to the severe condition of COVID-19 was 3.47 (95% confidence interval [CI]: 1.02-11.75; P = .046) and 3.77 (95% CI: 1.33-10.71; P = .013) after adjustment for baseline date and laboratory indices, respectively. Anemia is an independent risk factor associated with the severe illness of COVID-19, and healthcare professionals should be more sensitive to the hemoglobin levels of COVID-19 patients on admission. Awareness of anemia as a risk factor for COVID-19 was of great significance.