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Background Idiopathic nephrotic syndrome (INS) is classified in children according to response to initial corticosteroid therapy into steroid-sensitive (SSNS) and steroid-resistant nephrotic syndrome (SRNS), and in adults according to histology into minimal change disease (MCD) and focal segmental glomerulosclerosis (FSGS). However, there is well-recognised phenotypic overlap between these entities. Genome-wide association studies (GWAS) have shown a strong association between SSNS and variation at HLA, suggesting an underlying immunological basis. We sought to determine whether a risk score generated from genetic variants associated with SSNS could be used to gain insight into the pathophysiology of INS presenting in other ways. Methods We developed an SSNS genetic risk score (SSNS-GRS) from the five variants independently associated with childhood SSNS in a previous European GWAS. We quantified SSNS-GRS in independent cohorts of European individuals with childhood SSNS, non-monogenic SRNS, MCD, and FSGS, and contrasted them with SSNS-GRS quantified in individuals with monogenic SRNS, membranous nephropathy (a different immune-mediated disease-causing nephrotic syndrome), and healthy controls. Results The SSNS-GRS was significantly elevated in cohorts with SSNS, non-monogenic SRNS, MCD, and FSGS compared to healthy participants and those with membranous nephropathy. The SSNS-GRS in all cohorts with non-monogenic INS were also significantly elevated compared to those with monogenic SRNS. Conclusions The shared genetic risk factors among patients with different presentations of INS strongly suggests a shared autoimmune pathogenesis when monogenic causes are excluded. Use of the SSNS-GRS, in addition to testing for monogenic causes, may help to classify patients presenting with INS. Graphical abstract, Author(s): Mallory L. Downie [sup.1] [sup.2] , Sanjana Gupta [sup.1] , Melanie M. Y. Chan [sup.1] , Omid Sadeghi-Alavijeh [sup.1] , Jingjing Cao [sup.3] , Rulan S. Parekh [sup.3] [sup.4] [...]

The majority of calcium filtered by the glomerulus is reabsorbed along the nephron. Most is reabsorbed from the proximal tubule (> 60%) via a paracellular pathway composed of the tight junction proteins claudins-2 and -12, a process driven by sodium and consequently water reabsorption. The thick ascending limb reabsorbs the next greatest amount of calcium (20-25%), also by a paracellular pathway composed of claudins-16 and -19. This pathway is regulated by the CaSR, whose activity increases the expression of claudin-14, a protein that blocks paracellular calcium reabsorption. The fine tuning of urinary calcium excretion occurs in the distal convoluted and connecting tubule by a transcellular pathway composed of the apical calcium channel TRPV5, the calcium shuttling protein calbindin-D.sub.28K and the basolateral proteins PMCA1b and the sodium calcium exchanger, NCX. Not surprisingly, mutations in a subset of these genes cause monogenic disorders with hypercalciuria as a part of the phenotype. More commonly, 'idiopathic' hypercalciuria is encountered clinically with genetic variations in CLDN14, the CASR and TRPV5 associating with kidney stones and increased urinary calcium excretion. An understanding of the molecular pathways conferring kidney tubular calcium reabsorption is employed in this review to help explain how dietary and medical interventions for this disorder lower urinary calcium excretion., Author(s): Mallory L Downie [sup.1] [sup.2] , R. Todd Alexander [sup.3] [sup.4] [sup.5] Author Affiliations: (1) grid.83440.3b, 0000000121901201, Department of Renal Medicine, University College London, , London, UK (2) grid.424537.3, [...]

Steroid-sensitive nephrotic syndrome (SSNS) is the most common form of nephrotic syndrome in childhood and there is growing evidence that genetics play a role in the susceptibility for the disease. Familial clustering has been observed and has led to several studies on familial SSNS trying to identify a monogenic cause of the disease. Until now, however, none of these have provided convincing evidence for Mendelian inheritance. This and the phenotypic variability within SSNS suggest a complex inheritance pattern, where multiple variants and interactions between those and the environment play roles in disease development. Genome-wide association studies (GWASs) have been used to investigate this complex disease. We herein highlight new insights in the genetics of the disease provided by GWAS and identify how these insights fit into our understanding of the pathogenesis of SSNS., Author(s): Stephanie Dufek-Kamperis [sup.1] [sup.2] , Robert Kleta [sup.2] [sup.3] , Detlef Bockenhauer [sup.2] [sup.3] , Daniel Gale [sup.2] , Mallory L. Downie [sup.2] [sup.3] Author Affiliations: (1) grid.154185.c, 0000 [...]

LGBTQ + medical trainees experience significant discrimination. These individuals are stigmatized within a hetero- and cis-normative system, resulting in poorer outcomes in mental health and increased stress regarding career trajectory compared with their hetero- and cis-identifying counterparts. However, literature on the barriers experienced during medical training in this marginalized group is limited to small heterogeneous studies. This scoping review collates and explores prominent themes in existing literature on the personal and professional outcomes of LGBTQ + medical trainees. We searched five library databases (SCOPUS, Ovid-Medline, ERIC, PsycINFO and EMBASE) for studies that investigated LGBTQ + medical trainees' academic, personal, or professional outcomes. Screening and full text review were performed in duplicate, and all authors participated in thematic analysis to determine emerging themes, which were iteratively reviewed to consensus. From 1809 records, 45 met inclusion criteria (κ = 0.57). Major themes that emerged in the literature included the prevalence of discrimination and mistreatment faced by LGBTQ + medical trainees from colleagues and superiors, concerns regarding disclosure of sexual and/or gender minority identity, and overall negative impacts on mental health including higher rates of depression, substance use, and suicidal ideation. There was a noted lack of inclusivity in medical education and having an LGBTQ + identity had a large impact on career trajectory. Community with peers and mentors was an important determinant of success and belonging. There was a noteworthy lack of research on intersectionality or positive interventions that improved outcomes for this population. This scoping review highlighted important barriers facing LGBTQ + medical trainees, identifying substantial gaps in the existing literature. Research on supportive interventions and predictors of training success is lacking and will be important to foster an inclusive education system. These findings provide critical insights for education leaders and researchers to help create and evaluate inclusive and empowering environments for trainees. [ABSTRACT FROM AUTHOR]

Background Sarcoidosis is a multisystem granulomatous disease of unknown etiology that rarely presents in childhood. Here, we report a case of pediatric sarcoidosis, presenting with renal failure and hypercalcemia. Case diagnosis/Treatment A previously well 14-year-old Caucasian boy was admitted to the Hospital for Sick Children, Canada, for hypertension and renal failure following work-up by his family physician for initial concerns of growth failure. On admission, his weight was 35 kg ( Conclusions This case represents an atypical presentation of a rare pediatric disease and highlights the spectrum of renal manifestations and treatment options in sarcoidosis., Author(s): Mallory L. Downie [sup.1] , Jaap Mulder [sup.1] , Rayfel Schneider [sup.2] , Lillian Lim [sup.2] , Nasrin Tehrani [sup.3] , Jonathan D. Wasserman [sup.4] , Shai Fuchs [sup.4] [...]

Background Primary nephrogenic diabetes insipidus (NDI) is a rare disorder and little is known about treatment practices and long-term outcome. Methods Paediatric and adult nephrologists contacted through European professional organizations entered data in an online form. Results Data were collected on 315 patients (22 countries, male 84%, adults 35%). Mutation testing had been performed in 270 (86%); pathogenic variants were identified in 258 (96%). The median (range) age at diagnosis was 0.6 (0.0–60) years and at last follow-up 14.0 (0.1–70) years. In adults, height was normal with a mean (standard deviation) score of −0.39 (±1.0), yet there was increased prevalence of obesity (body mass index >30 kg/m2; 41% versus 16% European average; P < 0.001). There was also increased prevalence of chronic kidney disease (CKD) Stage ≥2 in children (32%) and adults (48%). Evidence of flow uropathy was present in 38%. A higher proportion of children than adults (85% versus 54%; P < 0.001) received medications to reduce urine output. Patients ≥25 years were less likely to have a university degree than the European average (21% versus 35%; P = 0.003) but full-time employment was similar. Mental health problems, predominantly attention-deficit hyperactivity disorder (16%), were reported in 36% of patients. Conclusion This large NDI cohort shows an overall favourable outcome with normal adult height and only mild to moderate CKD in most. Yet, while full-time employment was similar to the European average, educational achievement was lower, and more than half had urological and/or mental health problems. [ABSTRACT FROM AUTHOR]

Context: Observational studies investigating the role of vitamin D in renal function have yielded inconsistent results. Objective: We tested whether 25-hydroxyvitamin D (25[OH]D) serum levels are associated with renal function, and inversely, whether altered renal function causes changes in 25(OH)D, using Mendelian randomization (MR). Methods: In this two-sample MR study, we used single nucleotide polymorphisms (SNP) associated with 25(OH)D in 443 734 Europeans and evaluated their effects on estimated glomerular filtration rate (eGFR), blood urea nitrogen (BUN), chronic kidney disease (CKD) risk and progression in genome-wide association studies totaling over 1 million Europeans. To control for pleiotropy, we also used SNPs solely in DHCR7, CYP2R1, and GC, all genes with known roles in vitamin D metabolism. We performed a reverse MR, using SNPs for the above indices of renal function to study causal effects on 25(OH)D levels. Results: We did not find robust evidence supporting effects of 25(OH)D on eGFR, BUN, and CKD or its progression. Our inverse variance weighted MR demonstrated a 0.56 decrease in standardized log-transformed 25(OH)D (95% CI-0.73, -0.41; P=2.89 x 10-12) per unit increase in log-transformed eGFR. Increased BUN was associated with increased 25(OH)D (β=0.25, 95% CI 0.15, 0.36; P=4.12 x 10-6 per unit increase in log-transformed BUN). Finally, genetically predicted CKD conferred a 0.05 increase in standardized log-transformed 25(OH)D level (95% CI 0.04, 0.06; P=1.06 x 10-13). Other MR methods confirmed the findings of the main analyses. Conclusion: Genetically predicted CKD, increased BUN, and decreased eGFR are associated with increased 25(OH)D levels, but we found no causal effect of 25(OH)D on renal function in Europeans. [ABSTRACT FROM AUTHOR]

The kidney tubules provide homeostasis by maintaining the external milieu that is critical for proper cellular function. Without homeostasis, there would be no heartbeat, no muscle movement, no thought, sensation, or emotion. The task is achieved by an orchestra of proteins, directly or indirectly involved in the tubular transport of water and solutes. Inherited tubulopathies are characterized by impaired function of one or more of these specific transport molecules. The clinical consequences can range from isolated alterations in the concentration of specific solutes in blood or urine to serious and life-threatening disorders of homeostasis. In this review, we focus on genetic aspects of the tubulopathies and how genetic investigations and kidney physiology have crossfertilized each other and facilitated the identification of these disorders and their molecular basis. In turn, clinical investigations of genetically defined patients have shaped our understanding of kidney physiology., (Copyright © 2021 by the American Society of Nephrology.)

Background: Primary nephrogenic diabetes insipidus (NDI) is a rare disorder and little is known about treatment practices and long-term outcome., Methods: Paediatric and adult nephrologists contacted through European professional organizations entered data in an online form., Results: Data were collected on 315 patients (22 countries, male 84%, adults 35%). Mutation testing had been performed in 270 (86%); pathogenic variants were identified in 258 (96%). The median (range) age at diagnosis was 0.6 (0.0-60) years and at last follow-up 14.0 (0.1-70) years. In adults, height was normal with a mean (standard deviation) score of -0.39 (±1.0), yet there was increased prevalence of obesity (body mass index >30 kg/m2; 41% versus 16% European average; P < 0.001). There was also increased prevalence of chronic kidney disease (CKD) Stage ≥2 in children (32%) and adults (48%). Evidence of flow uropathy was present in 38%. A higher proportion of children than adults (85% versus 54%; P < 0.001) received medications to reduce urine output. Patients ≥25 years were less likely to have a university degree than the European average (21% versus 35%; P = 0.003) but full-time employment was similar. Mental health problems, predominantly attention-deficit hyperactivity disorder (16%), were reported in 36% of patients., Conclusion: This large NDI cohort shows an overall favourable outcome with normal adult height and only mild to moderate CKD in most. Yet, while full-time employment was similar to the European average, educational achievement was lower, and more than half had urological and/or mental health problems., (© The Author(s) 2020. Published by Oxford University Press on behalf of ERA-EDTA. All rights reserved.)