Relationship between cortical and medullary thickness and glomerular filtration rate among living kidney donors.

The relationship between the kidney cortex and medulla is not well understood in healthy populations. This study characterised the relationship between cortical/medullary thickness and measured glomerular filtration rate (GFR) in 390 living kidney donors. A positive relationship was observed between medullary, but not cortical, thickness and GFR. We propose that this reflects a correlation between juxtamedullary nephron number and GFR.

Effectiveness of growth hormone on growth and final height in paediatric chronic kidney disease.

BACKGROUND: The effectiveness of rhGH on growth and final height (FH) was determined in children with CKD and kidney failure using data linkage from two national databases. METHODS: Data on Australian children with CKD and kidney failure treated with rhGH were obtained by linking ANZDATA and OzGrow registries. The CKD cohort included children treated with rhGH prior to kidney replacement therapy (KRT). The KRT cohort consisted of children with kidney failure, some received rhGH, and some were untreated. Height standard deviation scores (Ht-SDS) were calculated with final height defined as last height recorded in girls > 16 years of age and boys > 17 years of age. RESULTS: In the CKD group, there were 214 children treated with rhGH prior to KRT. In the KRT group, there were 1,032 children, 202 (19%) treated with rhGH and 830 (81%) untreated. Growth significantly improved in the rhGH-treated CKD group (ΔHt-SDS = +0.80 [+0.68 to +0.92]; p < 0.001) and the rhGH-treated KRT group (ΔHt-SDS = +0.38 [+0.27 to +0.50]; p < 0.001). Within the KRT cohort, final height was available for 423 patients (41%), of which 137 (32%) had been treated with rhGH. The rhGH-treated group demonstrated marginally better catch-up growth (ΔHt-SDS = +0.05 [-0.18 to 0.29]) compared to the non-rhGH-treated group (ΔHt-SDS = -0.03 [-0.16 to 0.10]; p = 0.49). CONCLUSIONS: This large linkage study confirms rhGH is effective in improving height in children with CKD pre-KRT. However, rhGH appears to have a variable impact on growth once children have commenced KRT resulting in a marginal impact on final height.

WT1 complete gonadal dysgenesis with membranoproliferative glomerulonephritis: case series and literature review.

BACKGROUND: Intronic WT1 mutations are usually causative of Frasier syndrome with focal segmental glomerulosclerosis as the characteristic nephropathy. Membranoproliferative glomerulonephritis is not commonly associated with disorders of sex development but has been recently identified as a WT1-associated nephropathy, but usually in cases of exonic mutations in either isolated Wilms tumor or Denys-Drash syndrome. METHODS: The clinical and genetic data from 3 individuals are reported. RESULTS: This report describes the kidney manifestations in 3 individuals from 2 unrelated families with Frasier syndrome intronic WT1 mutations, noting that 2 of the 3 individuals have histologically confirmed membranoproliferative glomerulonephritis. CONCLUSIONS: These case reports support expansion of the clinical spectrum of the kidney phenotypes associated with Frasier syndrome providing evidence of an association between WT1 mutation and an immune complex-related membranoproliferative glomerulonephritis. A higher resolution version of the Graphical abstract is available as Supplementary information.

Patient-iPSC-Derived Kidney Organoids Show Functional Validation of a Ciliopathic Renal Phenotype and Reveal Underlying Pathogenetic Mechanisms.

Despite the increasing diagnostic rate of genomic sequencing, the genetic basis of more than 50% of heritable kidney disease remains unresolved. Kidney organoids differentiated from induced pluripotent stem cells (iPSCs) of individuals affected by inherited renal disease represent a potential, but unvalidated, platform for the functional validation of novel gene variants and investigation of underlying pathogenetic mechanisms. In this study, trio whole-exome sequencing of a prospectively identified nephronophthisis (NPHP) proband and her parents identified compound-heterozygous variants in IFT140, a gene previously associated with NPHP-related ciliopathies. IFT140 plays a key role in retrograde intraflagellar transport, but the precise downstream cellular mechanisms responsible for disease presentation remain unknown. A one-step reprogramming and gene-editing protocol was used to derive both uncorrected proband iPSCs and isogenic gene-corrected iPSCs, which were differentiated to kidney organoids. Proband organoid tubules demonstrated shortened, club-shaped primary cilia, whereas gene correction rescued this phenotype. Differential expression analysis of epithelial cells isolated from organoids suggested downregulation of genes associated with apicobasal polarity, cell-cell junctions, and dynein motor assembly in proband epithelial cells. Matrigel cyst cultures confirmed a polarization defect in proband versus gene-corrected renal epithelium. As such, this study represents a "proof of concept" for using proband-derived iPSCs to model renal disease and illustrates dysfunctional cellular pathways beyond the primary cilium in the setting of IFT140 mutations, which are established for other NPHP genotypes.

Renal tumors in tuberous sclerosis complex.

Tuberous sclerosis complex (TSC) is a multisystem hereditary disorder characterized by the growth of benign tumors (hamartomas) in multiple organs, including the kidneys. Renal angiomyolipomas (AML) are a major diagnostic feature of TSC and are present in the majority of patients by adulthood. However, AML are usually asymptomatic during childhood when neurological and developmental manifestations are the main source of morbidity. Kidney manifestations of TSC have historically been the main cause of morbidity and mortality of adults with TSC. The recognition that the complications of TSC are caused by dysregulation of the mammalian target of rapamycin (mTOR) pathway has led to an enormous progress in the management of patients with TSC in the last two decades, the establishment of diagnostic guidelines, and trials which have shown the therapeutic benefit of mTOR inhibitors. Kidney surveillance of children with TSC now provides the opportunity for timely interventions to reduce the impact of TSC in adulthood. In this review, we discuss the current management of kidney tumors associated with TSC, including the diagnosis, surveillance, and treatment options for these lesions. We also present outcome data from international registries demonstrating the effectiveness of the current management strategies. With clear management guidelines and efficient treatment of kidney tumors, we envisage that the long-term outcomes of patients with TSC will further improve in the future.

Improve in-depth immunological risk assessment to optimize genetic-compatibility and clinical outcomes in child and adolescent recipients of parental donor kidney transplants: protocol for the INCEPTION study.

BACKGROUND: Parental donor kidney transplantation is the most common treatment option for children and adolescents with kidney failure. Emerging data from observational studies have reported improved short- and medium-term allograft outcomes in recipients of paternal compared to maternal donors. The INCEPTION study aims to identify potential differences in immunological compatibility between maternal and paternal donor kidneys and ascertain how this affects kidney allograft outcomes in children and adolescents with kidney failure. METHODS: This longitudinal observational study will recruit kidney transplant recipients aged ≤18 years who have received a parental donor kidney transplant across 4 countries (Australia, New Zealand, United Kingdom and the Netherlands) between 1990 and 2020. High resolution human leukocyte antigen (HLA) typing of both recipients and corresponding parental donors will be undertaken, to provide an in-depth assessment of immunological compatibility. The primary outcome is a composite of de novo donor-specific anti-HLA antibody (DSA), biopsy-proven acute rejection or allograft loss up to 60-months post-transplantation. Secondary outcomes are de novo DSA, biopsy-proven acute rejection, acute or chronic antibody mediated rejection or Chronic Allograft Damage Index (CADI) score of > 1 on allograft biopsy post-transplant, allograft function, proteinuria and allograft loss. Using principal component analysis and Cox proportional hazards regression modelling, we will determine the associations between defined sets of immunological and clinical parameters that may identify risk stratification for the primary and secondary outcome measures among young people accepting a parental donor kidney for transplantation. This study design will allow us to specifically investigate the relative importance of accepting a maternal compared to paternal donor, for families deciding on the best option for donation. DISCUSSION: The INCEPTION study findings will explore potentially differential immunological risks of maternal and paternal donor kidneys for transplantation among children and adolescents. Our study will provide the evidence base underpinning the selection of parental donor in order to achieve the best projected long-term kidney transplant and overall health outcomes for children and adolescents, a recognized vulnerable population. TRIAL REGISTRATION: The INCEPTION study has been registered with the Australian New Zealand Clinical Trials Registry, with the trial registration number of ACTRN12620000911998 (14th September 2020).

The impact of prematurity on postnatal growth of different renal compartments.

AIM: In humans, nephrogenesis ceases before birth, but the renal medulla compartment continues to develop after birth. We aim to evaluate the relative growth of different renal compartments in preterm babies compared with age-matched term babies, and explore the impact of premature birth on postnatal renal maturation, remodelling and possible long-term implications. METHODS: This retrospective study compared the renal ultrasonographic images between preterm babies and term infants. Ultrasound images were obtained at 32 weeks (preterm), 37 weeks and at 6 months of age. Kidney volume, length, renal cortex and medulla thickness were measured and compared between preterm and term babies. RESULTS: Preterm babies were lighter in body weight and shorter for crown-heel length at age-matched 37 weeks. All kidney growth parameters were also smaller compared with term babies. However, by 6 months of age kidney volume and length measurements were no longer significantly different between the two groups though preterm babies were still significantly lighter and shorter. The catch-up of the overall kidney growth in preterm babies was mainly attributed to the hypertrophic growth of the renal cortex while the postnatal renal medulla growth was disrupted. This trend continued as the renal cortical thickness became significantly larger while the medulla became smaller in preterm babies at 6 months of age, compared with age-matched term baby. CONCLUSIONS: In preterm babies, the renal cortical region undergoes accelerated growth after birth while the renal medulla growth lags behind. Further investigations will be necessary to determine whether this has a negative impact on renal function later in life.

Protocol and establishment of a Queensland renal biopsy registry in Australia.

BACKGROUND: Renal biopsy is often required to obtain information for diagnosis, management and prognosis of kidney disease that can be broadly classified into acute kidney injury (AKI) and chronic kidney disease (CKD). The most common conditions identified on renal biopsy are glomerulonephritis and tubulo-interstitial disorders. There is a paucity of information on management strategies and therapeutic outcomes in AKI and CKD patients. A renal biopsy registry will provide information on biopsy-proven kidney disorders to improve disease understanding and tracking, healthcare planning, patient care and outcomes. METHODS: A registry of patients, that includes biopsy-proven kidney disease, was established through the collaboration of nephrologists from Queensland Hospital and Health Services and pathologists from Pathology Queensland services. The registry is in keeping with directions of the Advancing Kidney Care 2026 Collaborative, established in September 2018 as a Queensland Health initiative. Phase 1 of the registry entailed retrospective acquisition of data from all adult native kidney biopsies performed in Queensland, Australia, from 2002 to 2018. Data were also linked with the existing CKD.QLD patient registry. From 2019 onwards, phase 2 of the registry involves prospective collection of all incident consenting patients referred to Queensland public hospitals and having a renal biopsy. Annual reports on patient outcomes will be generated and disseminated. DISCUSSION: Establishment of the Queensland Renal Biopsy Registry (QRBR) aims to provide a profile of patients with biopsy-proven kidney disease that will lead to better understanding of clinico-pathological association and facilitate future research. It is expected to improve patient care and outcomes.

Treatment and long-term outcome in primary distal renal tubular acidosis.

BACKGROUND: Primary distal renal tubular acidosis (dRTA) is a rare disorder, and we aimed to gather data on treatment and long-term outcome. METHODS: We contacted paediatric and adult nephrologists through European professional organizations. Responding clinicians entered demographic, biochemical, genetic and clinical data in an online form. RESULTS: Adequate data were collected on 340 patients (29 countries, female 52%). Mutation testing had been performed on 206 patients (61%); pathogenic mutations were identified in 170 patients (83%). The median (range) presentation age was 0.5 (0-54) years and age at last follow-up was 11.0 (0-70.0) years. Adult height was slightly below average with a mean (SD score) of -0.57 (±1.16). There was an increased prevalence of chronic kidney disease (CKD) Stage ≥2 in children (35%) and adults (82%). Nephrocalcinosis was reported in 88%. Nephrolithiasis was more common with SLC4A1 mutations (42% versus 21%). Thirty-six percent had hearing loss, particularly in ATP6V1B1 (88%). The median (interquartile range) prescribed dose of alkali (mEq/kg/day) was 1.9 (1.2-3.3). Adequate metabolic control (normal plasma bicarbonate and normocalciuria) was achieved in 158 patients (51%), more commonly in countries with higher gross domestic product (67% versus 23%), and was associated with higher height and estimated glomerular filtration rate. CONCLUSION: Long-term follow-up from this large dRTA cohort shows an overall favourable outcome with normal adult height for most and no patient with CKD Stage 5. However, 82% of adult patients have CKD Stages 2-4. Importance of adequate metabolic control was highlighted by better growth and renal function but was achieved in only half of patients.

Renal genetics in Australia: Kidney medicine in the genomic age.

There have been few new therapies for patients with chronic kidney disease in the last decade. However, the management of patients affected by genetic kidney disease is rapidly evolving. Inherited or genetic kidney disease affects around 10% of adults with end-stage kidney disease and up to 70% of children with early onset kidney disease. Advances in next-generation sequencing have enabled rapid and cost-effective sequencing of large amounts of DNA. Next-generation sequencing-based diagnostic tests now enable identification of a monogenic cause in around 20% of patients with early-onset chronic kidney disease. A definitive diagnosis through genomic testing may negate the need for prolonged diagnostic investigations and surveillance, facilitate reproductive planning and provide accurate counselling for at-risk relatives. Genomics has allowed the better understanding of disease pathogenesis, providing prognostic information and facilitating development of targeted treatments for patients with inherited or genetic kidney disease. Although genomic testing is becoming more readily available, there are many challenges to implementation in clinical practice. Multidisciplinary renal genetics clinics serve as a model of how some of these challenges may be overcome. Such clinics are already well established in most parts of Australia, with more to follow in future. With the rapid pace of new technology and gene discovery, collaboration between expert clinicians, laboratory and research scientists is of increasing importance to maximize benefits to patients and health-care systems.

Therapeutic plasma exchange normalizes insulin-mediated response in a child with type 1 diabetes and insulin autoimmune syndrome.

BACKGROUND: Insulin autoimmune syndrome (IAS), characterized by glycemic dysregulation and life-threatening hypoglycemia, can occur in patients with type 1 diabetes (T1D). Diagnostic confirmation is complex but important in order to ensure timely initiation of definitive therapy. AIMS: We aimed to quantitate the degree of immunoglobulin-insulin complex (IIC) formation and its effects on glycemic control in a patient with T1D and IAS compared with T1D and non-T1D controls and before and after therapeutic plasma exchange (TPE). MATERIALS & METHODS: The prospective descriptive study was conducted between June 2015 and December 2015 in a quaternary children's hospital in Brisbane, Australia. Percent Free "Immunoreactive" Insulin (%FII) as assessed by polyethylene glycol precipitation studies and its relationship to plasma glucose and serum insulin concentration. RESULTS: Samples from the patient with T1D and IAS demonstrated lower mean %FII compared to T1D (23.8 ± 2.0 vs 52.0 ± 6.7; P < .0001) and non-T1D (23.8 ± 2.0 vs 102.9 ± 2.7; P < .0001) controls. This was associated with loss of glycemic predictability and frequent severe hypoglycemia. TPE increased %FII (23.8 ± 2.0 before TPE vs 83.6 ± 2.5 after TPE, P < .0001) and reestablished plasma glucose responsiveness to exogenous insulin. DISCUSSION: IAS should be considered in T1D patients with unexplained glycemic instability and hypoglycemia. The laboratory plays an integral diagnostic role. CONCLUSION: TPE is an effective method for removing IICs and normalizing insulin-mediated glucose responses.

The impact of donor/recipient age difference and HLA mismatch on graft outcome in pediatric kidney transplantation.

BACKGROUND: Understanding the relationship between the factors that influence long-term kidney transplant survival remains a key priority for pediatric nephrologists. We assessed the relative impact of donor/recipient age difference and HLA matching on long-term graft outcomes. METHODS: We conducted a retrospective cohort study of pediatric and adolescent recipients who received a primary kidney transplant in Australia and New Zealand between January 1, 1990, and December 31, 2015. The primary outcome was graft survival analyzed by Kaplan-Meier method. RESULTS: During the 26-year period, 1134 primary (395 DD and 739 LD) kidney transplants were performed in recipients less than 20 years of age. The median follow-up time was 10.2 years. Overall, 405 patients (35.7%) lost their transplant with graft survival 93.8% at 1 year, 82.5% at 5 years, 65.8% at 10 years, and 49.9% at 15 years post-transplant. There was consistently higher graft loss of DD kidneys as compared to LD kidneys at each time point. Both increasing donor/recipient age difference (aHR 1.11 per 10 years; 95% CI, 1.02-1.20; P = 0.009) and increasing HLA mismatch (aHR 1.20 per mismatch; 95% CI, 1.10-1.30; P < 0.001) were associated with decreased graft survival. CONCLUSIONS: Donor/recipient age difference and HLA matching are important factors influencing long-term graft outcomes in pediatric kidney transplantation. HLA mismatch remains a strong predictor of graft loss. For patients without the option of a LD, we suggest that the degree of HLA mismatch should not be discounted as part of the decision-making process of organ allocation.

Defects in the IFT-B component IFT172 cause Jeune and Mainzer-Saldino syndromes in humans.

Intraflagellar transport (IFT) depends on two evolutionarily conserved modules, subcomplexes A (IFT-A) and B (IFT-B), to drive ciliary assembly and maintenance. All six IFT-A components and their motor protein, DYNC2H1, have been linked to human skeletal ciliopathies, including asphyxiating thoracic dystrophy (ATD; also known as Jeune syndrome), Sensenbrenner syndrome, and Mainzer-Saldino syndrome (MZSDS). Conversely, the 14 subunits in the IFT-B module, with the exception of IFT80, have unknown roles in human disease. To identify additional IFT-B components defective in ciliopathies, we independently performed different mutation analyses: candidate-based sequencing of all IFT-B-encoding genes in 1,467 individuals with a nephronophthisis-related ciliopathy or whole-exome resequencing in 63 individuals with ATD. We thereby detected biallelic mutations in the IFT-B-encoding gene IFT172 in 12 families. All affected individuals displayed abnormalities of the thorax and/or long bones, as well as renal, hepatic, or retinal involvement, consistent with the diagnosis of ATD or MZSDS. Additionally, cerebellar aplasia or hypoplasia characteristic of Joubert syndrome was present in 2 out of 12 families. Fibroblasts from affected individuals showed disturbed ciliary composition, suggesting alteration of ciliary transport and signaling. Knockdown of ift172 in zebrafish recapitulated the human phenotype and demonstrated a genetic interaction between ift172 and ift80. In summary, we have identified defects in IFT172 as a cause of complex ATD and MZSDS. Our findings link the group of skeletal ciliopathies to an additional IFT-B component, IFT172, similar to what has been shown for IFT-A.

A retrospective review of telehealth services for children referred to a paediatric nephrologist.

BACKGROUND: Telemedicine has emerged as an alternative mode of health care delivery over the last decade. To date, there is very limited published information in the field of telehealth and paediatric nephrology. The aim of this study was to review our experience with paediatric telenephrology in Queensland, Australia. METHODS: A retrospective audit of paediatric nephrology telehealth consultations to determine the nature of the telehealth activity, reasons for referral to telehealth, and to compare costs and potential savings of the telehealth service. RESULTS: During a ten-year period (2004 - 2013), 318 paediatric telenephrology consultations occurred for 168 patients (95 male) with the median age of 8 years (range 3 weeks to 24 years). Congenital anomalies of the kidney and urinary tract (30 %), followed by nephrotic syndrome (16 %), kidney transplant (12 %), and urinary tract infection (9 %) were the most common diagnoses. The estimated cost savings associated with telehealth were $31,837 in 2013 (average saving of $505 per consultation). CONCLUSIONS: Our study suggests that paediatric telenephrology is a viable and economic method for patient assessment and follow up. The benefits include improved access to paediatric nephrology services for patients and their families, educational opportunity for the regional medical teams, and a substantial cost saving for the health care system.

A protocol for the identification and validation of novel genetic causes of kidney disease.

BACKGROUND: Genetic renal diseases (GRD) are a heterogeneous and incompletely understood group of disorders accounting for approximately 10 % of those diagnosed with kidney disease. The advent of Next Generation sequencing and new approaches to disease modelling may allow the identification and validation of novel genetic variants in patients with previously incompletely explained or understood GRD. METHODS/DESIGN: This study will recruit participants in families/trios from a multidisciplinary sub-specialty Renal Genetics Clinic where known genetic causes of GRD have been excluded or where genetic testing is not available. After informed patient consent, whole exome and/or genome sequencing will be performed with bioinformatics analysis undertaken using a customised variant assessment tool. A rigorous process for participant data management will be undertaken. Novel genetic findings will be validated using patient-derived induced pluripotent stem cells via differentiation to renal and relevant extra-renal tissue phenotypes in vitro. A process for managing the risk of incidental findings and the return of study results to participants has been developed. DISCUSSION: This investigator-initiated approach brings together experts in nephrology, clinical and molecular genetics, pathology and developmental biology to discover and validate novel genetic causes for patients in Australia affected by GRD without a known genetic aetiology or pathobiology.

Urinary Chloride Excretion Postcardiopulmonary Bypass in Pediatric Patients-A Pilot Study.

The aim of this study was to describe renal chloride metabolism following cardiopulmonary bypass (CPB) surgery in pediatric patients. A prospective observational trial in a tertiary pediatric intensive care unit (PICU) with 20 recruited patients younger than 2 years following CPB surgery was conducted. Urinary electrolytes, plasma urea, electrolytes, creatinine, and arterial blood gases were collected preoperatively, on admission to PICU and at standardized intervals thereafter. The urinary and plasma strong ion differences (SID) were calculated from these results at each time point. Fluid input and output and electrolyte and drug administration were also recorded. Median chloride administration was 67.7 mmol/kg over the first 24 hours. Urinary chloride (mmol/L; median interquartile range [IQR]) was 30 (19, 52) prior to surgery, 15 (15, 65) on admission, and remained below baseline until 24 hours. Plasma chloride (mmol/L; median [IQR]) was 105 (98, 107) prior to surgery and 101 (101, 106) on admission to PICU. It then increased from baseline, but remained within normal limits, for the remainder of the study. The urinary SID increased from 49.8 (19.1, 87.2) preoperatively to a maximum of 122.7 (92.5, 151.8) at 6 hours, and remained elevated until 48 hours. Plasma and urinary chloride concentrations were not associated with the development of acute kidney injury. Urinary chloride excretion is impaired after CPB. The urinary SID increase associated with the decrease in chloride excretion suggests impaired production and/or excretion of ammonium by the nephron following CPB, with gradual recovery postoperatively.

Rare SH2B3 coding variants in lupus patients impair B cell tolerance and predispose to autoimmunity.

Systemic lupus erythematosus (SLE) is a heterogeneous autoimmune disease with a clear genetic component. While most SLE patients carry rare gene variants in lupus risk genes, little is known about their contribution to disease pathogenesis. Amongst them, SH2B3-a negative regulator of cytokine and growth factor receptor signaling-harbors rare coding variants in over 5% of SLE patients. Here, we show that unlike the variant found exclusively in healthy controls, SH2B3 rare variants found in lupus patients are predominantly hypomorphic alleles, failing to suppress IFNGR signaling via JAK2-STAT1. The generation of two mouse lines carrying patients' variants revealed that SH2B3 is important in limiting the number of immature and transitional B cells. Furthermore, hypomorphic SH2B3 was shown to impair the negative selection of immature/transitional self-reactive B cells and accelerate autoimmunity in sensitized mice, at least in part due to increased IL-4R signaling and BAFF-R expression. This work identifies a previously unappreciated role for SH2B3 in human B cell tolerance and lupus risk.

Urinary tract obstruction in the mouse: the kinetics of distal nephron injury.

Congenital urinary tract obstruction is the single most important cause of childhood chronic kidney disease. We have previously demonstrated that human and primate fetal obstruction impairs the development, differentiation, and maturation of the kidney. Research using postnatal rodent models has primarily focused upon the role of proximal tubular injury, with few reports of collecting duct system pathology or the suitability of the postnatal models for examining injury to the distal nephron. We have employed the mouse unilateral ureteric obstruction (UUO) model and examined time points ranging from 1 to 14 days of obstruction. Many of the key features of fetal collecting duct injury are replicated in the postnatal mouse model of obstruction. Obstruction causes a sixfold increase in myofibroblast accumulation, two- to threefold dilatation of tubules of the distal nephron, 65% reduction of principal cell aquaporin 2 expression, 75% reduction of collecting duct intercalated cell abundance, and disruption of E-cadherin- and ßcatenin-mediated collecting duct epithelial adhesion. Notably, these features are shared by the distal and connecting tubules. This work confirms that distal nephron pathology is a significant component of postnatal mouse UUO. We have highlighted the utility of this model for investigating collecting duct and distal tubule injury and for identifying the underlying mechanisms of the distal nephron's contribution to the repair and fibrosis.

Henoch-Schönlein purpura in children.

Henoch-Schönlein purpura is the most common systemic vasculitis of childhood. In the majority of children, the outcome of Henoch-Schönlein purpura is excellent with spontaneous resolution of symptoms and signs. However, a small subset of patients will develop long-term sequelae in the form of chronic kidney disease. While the clinical presentation and diagnosis of Henoch-Schönlein purpura is straightforward, treatment of Henoch-Schönlein purpura nephritis and long-term renal outcomes of more severely affected children are less certain. This review article gives a general overview of Henoch-Schönlein purpura with emphasis on recently published information, including the new classification of childhood vasculitis, insights into pathogenesis of Henoch-Schönlein purpura and a summary of various treatments of established Henoch-Schönlein purpura nephritis.