We performed a genome-wide association study (GWAS) of IgA nephropathy (IgAN), the most common form of glomerulonephritis, with discovery and follow-up in 20,612 individuals of European and East Asian ancestry. We identified six novel genome-wide significant associations, four in ITGAM-ITGAX, VAV3 and CARD9 and two new independent signals at HLA-DQB1 and DEFA. We replicated the nine previously reported signals, including known SNPs in the HLA-DQB1 and DEFA loci. The cumulative burden of risk alleles is strongly associated with age at disease onset. Most loci are either directly associated with risk of inflammatory bowel disease (IBD) or maintenance of the intestinal epithelial barrier and response to mucosal pathogens. The geo-spatial distribution of risk alleles is highly suggestive of multi-locus adaptation and the genetic risk correlates strongly with variation in local pathogens, particularly helminth diversity, suggesting a possible role for host-intestinal pathogen interactions in shaping the genetic landscape of IgAN.

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

The Oxford Classification of IgA nephropathy (IgAN) includes the following four histologic components: mesangial (M) and endocapillary (E) hypercellularity, segmental sclerosis (S) and interstitial fibrosis/tubular atrophy (T). These combine to form the MEST score and are independently associated with renal outcome. Current prediction and risk stratification in IgAN requires clinical data over 2 years of follow-up. Using modern prediction tools, we examined whether combining MEST with cross-sectional clinical data at biopsy provides earlier risk prediction in IgAN than current best methods that use 2 years of follow-up data. We used a cohort of 901 adults with IgAN from the Oxford derivation and North American validation studies and the VALIGA study followed for a median of 5.6 years to analyze the primary outcome (50% decrease in eGFR or ESRD) using Cox regression models. Covariates of clinical data at biopsy (eGFR, proteinuria, MAP) with or without MEST, and then 2-year clinical data alone (2-year average of proteinuria/MAP, eGFR at biopsy) were considered. There was significant improvement in prediction by adding MEST to clinical data at biopsy. The combination predicted the outcome as well as the 2-year clinical data alone, with comparable calibration curves. This effect did not change in subgroups treated or not with RAS blockade or immunosuppression. Thus, combining the MEST score with cross-sectional clinical data at biopsy provides earlier risk prediction in IgAN than our current best methods.

BACKGROUND In the context of kidney transplantation, genomic incompatibilities between donor and recipient may lead to allosensitization against new antigens. We hypothesized that recessive inheritance of gene-disrupting variants may represent a risk factor for allograft rejection. METHODS We performed a two-stage genetic association study of kidney allograft rejection. In the first stage, we performed a recessive association screen of 50 common gene-intersecting deletion polymorphisms in a cohort of kidney transplant recipients. In the second stage, we replicated our findings in three independent cohorts of donor–recipient pairs. We defined genomic collision as a specific donor–recipient genotype combination in which a recipient who was homozygous for a gene-intersecting deletion received a transplant from a nonhomozygous donor. Identification of alloantibodies was performed with the use of protein arrays, enzyme-linked immunosorbent assays, and Western blot analyses. RESULTS In the discovery cohort, which included 705 recipients, we found a significant association with allograft rejection at the LIMS1 locus represented by rs893403 (hazard ratio with the risk genotype vs. nonrisk genotypes, 1.84; 95% confidence interval [CI], 1.35 to 2.50; P= 9.8×10−5). This effect was replicated under the genomic-collision model in three independent cohorts involving a total of 2004 donor–recipient pairs (hazard ratio, 1.55; 95% CI, 1.25 to 1.93; P = 6.5×10−5). In the combined analysis (discovery cohort plus replication cohorts), the risk genotype was associated with a higher risk of rejection than the nonrisk genotype (hazard ratio, 1.63; 95% CI, 1.37 to 1.95; P = 4.7×10−8). We identified a specific antibody response against LIMS1, a kidney-expressed protein encoded within the collision locus. The response involved predominantly IgG2 and IgG3 antibody subclasses. CONCLUSIONS We found that the LIMS1 locus appeared to encode a minor histocompatibility antigen. Genomic collision at this locus was associated with rejection of the kidney allograft and with production of anti-LIMS1 IgG2 and IgG3. (Funded by the Columbia University Transplant Center and others.)

Introduction: The scope of the impact of the COVID-19 pandemic on living donor kidney transplantation (LDKT) practices is not well defined. Methods: We surveyed US transplant programs to assess practices, strategies, and barriers to living LDKT during the COVID-19 pandemic. After institutional review board approval, the survey was distributed from 9 May 2020 to 30 May 2020 by e-mail and postings to professional society list-servs. Responses were stratified based on state COVID-19 cumulative incidence levels. Results: Staff at 118 unique centers responded, representing 61% of US living donor recovery programs and 75% of LKDT volume in the prepandemic year. Overall, 66% reported that LDKT surgery was on hold (81% in "high" vs. 49% in "low" COVID-19 cumulative incidence states). A total of 36% reported that evaluation of new donor candidates had paused, 27% reported that evaluations were very much decreased (>0% to <25% typical), and 23% reported that evaluations were moderately decreased (25% to <50% typical). Barriers to LDKT surgery included program concerns for donor (85%) and recipient (75%) safety, patient concerns (56%), elective case restrictions (47%), and hospital administrative restrictions (48%). Programs with higher local COVID-19 cumulative incidence reported more barriers related to staff and resource diversion. Most centers continuing donor evaluations used remote strategies (video, 82%; telephone, 43%). As LDKT resumes, all programs will screen for COVID-19, although timeframe and modalities will vary. Recommendations for presurgical self-quarantine are also variable. Conclusion: The COVID-19 pandemic has had broad impacts on LDKT practice. Ongoing research and consensus building are needed to reduce barriers, to guide optimal practices, and to support safe restoration of LDKT across centers.

An electronic survey canvassing current policies of transplant centers regarding a COVID‐19 vaccine mandate for transplant candidates and living donors was distributed to clinicians at US solid organ transplant centers performing transplants from October 14, 2021–November 15, 2021. Responses were received from staff at 141 unique transplant centers. These respondents represented 56.4% of US transplant centers, and responding centers performed 78.5% of kidney transplants and 82.4% of liver transplants in the year prior to survey administration. Only 35.7% of centers reported implementing a vaccine mandate, while 60.7% reported that vaccination was not required. A minority (42%) of responding centers with a vaccine mandate for transplant candidates also mandated vaccination for living organ donors. Centers with a vaccine mandate most frequently cited clinical evidence supporting the efficacy of pre‐transplant vaccination (82%) and stewardship obligations to ensure organs were transplanted into the lowest risk patients (64%). Centers without a vaccine mandate cited a variety of reasons including administrative, equity, and legal considerations for their decision. Transplant centers in the United States exhibit significant heterogeneity in COVID‐19 vaccination mandate policies for transplant candidates. While all centers encourage vaccination, most centers have not mandated COVID‐19 vaccination for candidates and living donors, citing administrative opposition, legal prohibitions, and concern about equity in access to transplants.

Renal insufficiency is a common complication early after hematopoietic stem cell transplantation (HSCT). Renal function as measured by creatinine clearance (CrCl) was prospectively evaluated in 47 patients undergoing allogeneic (n ¼ 22) or autologous (n ¼ 25) HSCT during the first 100 days. Renal dysfunction was classified as follows: Grade 0 (o25% decline in CrCl), Grade 1 (X25% decline in CrCl but o2 Â increase in serum creatinine), Grade 2 (X2 Â rise in serum creatinine but no need for dialysis) and Grade 3 (X2 Â rise in serum creatinine and need for dialysis). Thirty-three patients (70%) had Grade 1-3 renal dysfunction. Renal dysfunction was more common after myeloablative allogeneic HSCT (91%) than autologous HSCT (52%) (P ¼ 0.004), and was associated with a high risk of mortality (P ¼ 0.039). Sepsis in autologous HSCT patients and cyclosporine toxicity in allogeneic HSCT patients were associated with renal dysfunction. We conclude that autologous and allogeneic HSCT differ in the likelihood and causes of renal dysfunction.

Background It is unknown whether renal pathology lesions in immunoglobulin A nephropathy (IgAN) correlate with renal outcomes over decades of follow-up. Methods In 1130 patients of the original Validation Study of the Oxford Classification for IgA Nephropathy (VALIGA) cohort, we studied the relationship between the MEST score (mesangial hypercellularity, M; endocapillary hypercellularity, E; segmental glomerulosclerosis, S; tubular atrophy/interstitial fibrosis, T), crescents (C) and other histological lesions with both a combined renal endpoint [50% estimated glomerular filtration rate (eGFR) loss or kidney failure] and the rate of eGFR decline over a follow-up period extending to 35 years [median 7 years (interquartile range 4.1–10.8)]. Results In this extended analysis, M1, S1 and T1–T2 lesions as well as the whole MEST score were independently related with the combined endpoint (P &lt; 0.01), and there was no effect modification by age for these associations, suggesting that they may be valid in children and in adults as well. Only T lesions were associated with the rate of eGFR loss in the whole cohort, whereas C showed this association only in patients not treated with immunosuppression. In separate prognostic analyses, the whole set of pathology lesions provided a gain in discrimination power over the clinical variables alone, which was similar at 5 years (+2.0%) and for the whole follow-up (+1.8%). A similar benefit was observed for risk reclassification analyses (+2.7% and +2.4%). Conclusion Long-term follow-up analyses of the VALIGA cohort showed that the independent relationship between kidney biopsy findings and the risk of progression towards kidney failure in IgAN remains unchanged across all age groups and decades after the renal biopsy.