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IgA nephropathy (IgAN) is the most common glomerulonephritis worldwide. It is diagnosed based on clinical and histological features including predominant IgA deposits in kidney biopsy. The multi-hit theory, based on the production of GDIgA1 and anti-GDIgA1 antibodies, and complement activation via alternative and lectin pathways and also a genetic tendency are crucial in the pathogenesis of IgAN. The aim of the present review is to summarize the utility of routine diagnostic tests in IgA nephropathy, such as IgA and C3 in serum and kidney biopsy specimens, for predicting the disease progression. The paper also contains data on new markers used in the diagnosis and prognosis of IgA nephropathy.

Immunoglobulin A (IgA) vasculitis is the most common systemic vasculitis in the pediatric population. We present the case of a patient with IgA vasculitis with nephritis who developed cytomegalovirus (CMV) infection followed by Mycobacterium tuberculosis infection. In the literature, there are a few cases of IgA nephropathy accompanied by reactivation of CMV or tuberculosis. To the best of our knowledge, this is the first reported case of IgA vasculitis complicated by both CMV reactivation and tuberculosis. It is important to detect infections in patients with IgA vasculitis because they can induce and exacerbate the symptoms of the disease. Effective antimicrobial treatment facilitates the management of proteinuria and slows down the decline of renal function. Immunosuppressive therapy is a risk factor for reactivation of latent infections and makes patients more susceptible to its generalized and complicated course. This can be prevented by actively screening for hidden sites of infection.

Introduction The aim of the study was to compare the first year of disease in children with idiopathic nephrotic syndrome (INS) treated according to two prednisone dosing regimens: a weight-based schedule (2 mg/kg/24 h in the 1st month, 2 mg/kg/48 h in the 2nd month, with dose tapering during the following 4 months), and a body surface area (BSA)-based schedule (60 mg/m2/24 h in the 1st month, 40 mg/m2/48 h in the 2nd month, with dose tapering during the following 4 months). Material and methods In 2 groups of children treated with weight- and BSA-based regimens (20 patients, 3.13 ±1.01 years, treated in 2010-2013 and 20 patients, 5.13 ±2.86 years, treated in 2014-2016) clinical and anthropometrical parameters, number of INS relapses, total prednisone dose (mg/kg/year), and steroid adverse effects were compared during the first year of disease. Results Children treated with the weight-based steroid regimen received a higher total annual prednisone dose (259.06 ±79.54 vs. 185.83 ±72.67 mg/kg/24 h, p = 0.004) and had a shorter (though not significantly) period without prednisone (38.25 ±55.83 vs. 75.90 ±73.06 days, p = 0.062) compared to patients treated with the BSA-based regimen. There was no difference in number of relapses between groups (2.20 ±1.64 vs. 1.60 ±1.67, p = 0.190) but more patients relapsed in the weight-based group (19/20 vs. 13/20, p = 0.044). No differences in Z-score values of height, weight, and body mass index (BMI) were observed. No steroid-related adverse events were noted except for arterial hypertension (4/20 vs. 5/20 patients, p = 1.000). Conclusions The BSA-based regimen of prednisone dosing in children with INS reduces exposure to steroids and risk of relapse, as well as increases days off steroids in the first year compared to the weight-based regimen with a high second-month dose.

IgA nephropathy (IgAN) is a progressive form of kidney disease defined by glomerular deposition of IgA. We performed a genome-wide association study involving 10,146 kidney biopsy-diagnosed IgAN cases and 28,751 matched controls across 17 international cohorts. We defined 30 independent genome-wide significant risk loci jointly explaining 11% of disease risk. A total of 16 loci were novel, including TNFSF4, REL, CD28, CXCL8/PF4V1, LY86, LYN, ANXA3, TNFSF8/15, REEP3, ZMIZ1, RELA, ETS1, IGH, IRF8, TNFRSF13B and FCAR. The SNP-based heritability of IgAN was estimated at 23%. We observed a positive genetic correlation between IgAN and total serum IgA levels, allergy, tonsillectomy, and several infections, and a negative correlation with inflammatory bowel disease. All significant non-HLA loci shared with serum IgA levels had a concordant effect on the risk of IgAN. Moreover, IgAN loci were globally enriched in gene orthologs causing abnormal IgA levels when genetically manipulated in mice. The explained heritability was enriched in the regulatory elements of cells from the immune and hematopoietic systems and intestinal mucosa, providing support for the pathogenic role of extra-renal tissues. The polygenic risk of IgAN was associated with early disease onset, increased lifetime risk of kidney failure, as well as hematuria and several other traits in a phenome-wide association study of 590,515 individuals. In the comprehensive functional annotation analysis of candidate causal genes across genome-wide significant loci, we observed the convergence of biological candidates on a common set of inflammatory signaling pathways and cytokine ligand-receptor pairs, prioritizing potential new drug targets.

Abstract The aim of the study was to investigate the relationship between the severity of typical clinical symptoms, severity of histopathological lesions in kidney biopsies in IgA vasculitis nephritis (IgAVN) and to propose indications for kidney biopsy in children. Material and methods This retrospective study enrolled 106 patients, included in the IgAVN registry of Polish children, diagnosed by kidney biopsy. Renal and extrarenal symptoms at onset of the disease were analyzed. Biopsy results were assessed using Oxford classifications (MEST-C). The patients were divided into 3 groups depending on the severity of proteinuria: A-nephrotic proteinuria with hematuria; B-non-nephrotic proteinuria with hematuria; C-isolated hematuria. Results The first symptoms of nephropathy were observed at the 0.7 (1–128.4) months from the onset of extrarenal symptoms. Kidney biopsy was performed on 39 (6–782) days after the onset of nephropathy symptoms. MEST-C score 4 or 5 was significantly more frequent in children from group A than in groups B and C. Significantly higher mean MEST-C score was found in patients with abdominal symptoms than without. In group A: S0 and T0 we found in significantly shorter time to kidney biopsy than in S1, T1–2 p p = 0.004, sensitivity 0.895 specificity 0.444) T1–2 changes after 35 days (AUC 0.685, p = 0.022, sensitivity 0.750, specificity 0.615), and in goupn B T1–2 cut off is 74 days (AUC 0,738, p = 0.002, sensitivity 0.667, specificity 0.833). Conclusions In childhood IgAVN, the severity of changes in the urine is clearly reflected in the result of a kidney biopsy. The biopsy should be performed in patients with nephrotic proteinuria no later than 3 weeks after the onset of this symptom in order to promptly apply appropriate treatment and prevent disease progression. Accompanying abdominal symptoms predispose to higher MESTC score.

Aim of the study To evaluate the relationship between serum Gd-IgA1 (sGd-IgA1) and serum and urine TNFR1 (sTNFR1, uTNFR1) levels as possible prognostic factors in IgA nephropathy (IgAN) and IgA vasculitis nephritis (IgAVN). Material and methods From 299 patients from the Polish Registry of Pediatric IgAN and IgAVN, 60 children (24 IgAN and 36 IgAVN) were included in the study. The control group consisted of 20 healthy children. Proteinuria, haematuria, serum creatinine as well as IgA and C3 levels were measured and glomerular filtration rate (GFR) was calculated at onset and at the end of the follow-up. Kidney biopsy findings were evaluated using the Oxford classification. Serum Gd-IgA1 and serum and urine TNFR1 levels were measured at the end of follow-up. Results Serum Gd-IgA1 level was significantly higher in IgAN and IgAVN patients in comparison to the control group. Urine TNFR1 was significantly higher in IgAN than in IgAVN and the control group. We did not observe any differences in sTNFR1 level between IgAN, IgAVN and control groups. We found a positive correlation between Gd-IgA1 and creatinine (r = 0.34), and negative between Gd-IgA1 and GFR (r = -0.35) at the end of follow-up. We observed a negative correlation between uTNFR1/creatinine log and albumin level and protein/creatinine ratio. We did not find any correlations between Gd-IgA1 and TNFR1. Conclusions The prognostic value of sGd-IgA1 in children with IgAN and IgAVN has been confirmed. TNFR1 is not associated with Gd-IgA1 and is not a useful prognostic marker in children with IgAN/IgAVN and normal kidney function.

The aim of the study was to evaluate the influence of the intensity of mesangial C3 deposits in kidney biopsy and the serum C3 level on the clinical course and outcomes of IgAN in children. The study included 148 children from the Polish Pediatric IgAN Registry, diagnosed based on kidney biopsy. Proteinuria, creatinine, IgA, C3 were evaluated twice in the study group, at baseline and the end of follow-up. Kidney biopsy was categorized using the Oxford classification, with a calculation of the MEST-C score. The intensity of IgA and C3 deposits were rated from 0 to +4 in immunofluorescence microscopy. The intensity of mesangial C3 &gt, +1 deposits in kidney biopsy has an effect on renal survival with normal GFR in children with IgAN. A reduced serum C3 level has not been a prognostic factor in children but perhaps this finding should be confirmed in a larger group of children.

Although IgA nephropathy (IgAN) is a common cause of glomerulonephritis in children, the absence of a method to predict disease progression limits personalized risk-based treatment decisions. The adult International IgAN Prediction Tool comprises two validated Cox survival models that predict a 50% decline in estimated glomerular filtration rate (eGFR) or end stage kidney disease (ESKD) using clinical risk factors and Oxford MEST histology scores. Here, we updated the Prediction Tool for use in children using a multiethnic international cohort of 1,060 children with IgAN followed into adulthood. The updated pediatric Prediction Tool had better model fit than the original adult tool with lower Akaike Information Criterion, higher R2D and similar C-statistics. However, calibration showed very poor agreement between predicted and observed risks likely due to the observed disease trajectory in children. Therefore, the Tool was updated using a secondary outcome of a 30% reduction in eGFR or ESKD, resulting in better R2D (30.3%/22.2%) and similar C-statistics (0.74/0.68) compared to the adult tool but with good calibration. The trajectory of eGFR over time in children differed from adults being highly non-linear with an increase until 18 years old followed by a linear decline similar to that of adults. A higher predicted risk was associated with a smaller increase in eGFR followed by a more rapid decline, suggesting that children at risk of a 30% decrease in eGFR will eventually experience a larger 50% decrease in eGFR when followed into adulthood. As such, these two outcomes are analogous between pediatric and adult Prediction Tools. Thus, our pediatric Prediction Tool can accurately predict the risk of a 30% decline in eGFR or ESKD in children with IgAN.

Gordon's syndrome (pseudohipoaldosteronism type II) is a genetically determined, autosomal dominant type of monogenic hypertension caused by excessive reabsorption of chlorine accompanied by reabsorption of sodium and water.The case of a family (2 brothers: 12 and 16 years old and their father), in whom genetic tests confirmed the presence of a mutation characteristic of Gordon syndrome, despite the absence of hypertension in boys. Diagnostics of the family started with a 12-year-old boy because of observed for 2 years hyperkalemia and delayed growth and puberty. The physical examination showed low height (3c), discreet facial dysmorphic features (close spaced eyelid cracks, low-set ears) and lack of puberty, arterial pressure was normal. In laboratory tests, apart from hyperkalaemia at normal sodium level, hyperchloremia and metabolic acidosis were found. Plasma renin activity and aldosterone concentration were normal. There were no glomerular filtration abnormalities, renal parameters and kidney image in ultrasound examination were normal. Hyperkalemic tubular acidosis type IV was diagnosed and oral treatment with sodium bicarbonate was started. Due to the inability to achieve acidosis control with sodium bicarbonate and positive family history of hyperkalaemia and hypertension in the boy's father, the suspicion of Gordon syndrome was raised. Simultaneously, in the studies performed in the 16-year-old brother of the patient hyperkalemic acidosis, normal blood pressure and growth within normal limits for sex and age were found. The treatment of boys and father with hydrochlorothiazide was started, which resulted in the equalization of acidosis and calemia and rapid normalization of blood pressure in the father.In patients with tubular hyperkalemic acidosis, despite the absence of hypertension, Gordon's syndrome should be considered in the differentiation.

The proteasome to immunoproteasome (iPS) switch consists of β1, β2 and β5 subunit replacement by low molecular weight protein 2 (LMP2), LMP7 and multicatalytic endopeptidase-like complex-1 (MECL1) subunits, resulting in a more efficient peptide preparation for major histocompatibility complex 1 (MHC-I) presentation. It is activated by toll-like receptor (TLR) agonists and interferons and may also be influenced by genetic variation. In a previous study we found an iPS upregulation in peripheral cells of patients with immunoglobulin A nephropathy (IgAN). We aimed to investigate in 157 IgAN patients enrolled through the multinational Validation Study of the Oxford Classification of IgAN (VALIGA) study the relationships between iPS switch and estimated glomerular filtration rate (eGFR) modifications from renal biopsy to sampling. Patients had a previous long follow-up (6.4 years in median) that allowed an accurate calculation of their slope of renal function decline. We also evaluated the effects of the PSMB8/PSMB9 locus (rs9357155) associated with IgAN in genome-wide association studies and the expression of messenger RNAs (mRNAs) encoding for TLRs and CD46, a C3 convertase inhibitor, acting also on T-regulatory cell promotion, found to have reduced expression in progressive IgAN. We detected an upregulation of LMP7/β5 and LMP2/β1 switches. We observed no genetic effect of rs9357155. TLR4 and TLR2 mRNAs were found to be significantly associated with iPS switches, particularly TLR4 and LMP7/β5 (P 75th centile, i.e. −1.91 mL/min/1.73 m2/year) were characterized by significantly elevated LMP7/β5 mRNA (P = 0.04) and low CD46 mRNA expression (P

THE AIM OF THE STUDY The aim of the study was to evaluate the usefulness of urinary collagen IV (Col IV) excretion for predicting the severity of autoimmune renal inflammation in children with HSN (Henoch-Schonlein nephritis). MATERIAL AND METHODS We studied 26 children, in whom HSN was diagnosed based on kidney biopsy. In all patients, urinalysis was performed and 24-hour urinary protein excretion was measured at the onset of the disease. All kidney biopsies were also scored using the Oxford classification: M - mesangial hypercellularity score (M0 absent, M1 present); E - presence of endocapillary proliferation (E0 absent, E1 present), S - segmental glomerulosclerosis/adhesion (S0 absent, S1 present), T - tubular atrophy/interstitial fibrosis (T0 ≤ 25%, T1 26-50%, T2 > 50%). The MEST score was calculated as the sum of M + E + S + T. RESULTS Urinary Col IV level was significantly higher in the study group than in control group. Urinary Col IV level was insignificantly higher in group A (nephrotic proteinuria) compared to the B (non-nephrotic proteinuria) and C (without proteinuria).We found no significant differences in the age at the disease onset, severity of proteinuria, and Col IV between groups 1 (S0, T0) and 2.(S1,T1/T2). The MEST score was significantly higher in group 2 than group 1. CONCLUSIONS Urinary Col IV excretion in children with HSN may be related to the lesions severity by the Oxford classification but seems to be associated with the mean value (the MEST score). In younger children, a more aggressive disease course is observed, and thus earlier and more aggressive treatment should be considered in this group.

Nefronoftyza (NPH) jest genetycznie heterogenną chorobą nerek dziedziczoną autosomalnie recesywnie. Najczęściej (u 20% chorych) wykrywana jest mutacja w genie NPHP1. W obrazie klinicznym dominują zaburzenia zdolności zagęszczania moczu, obecność torbielek na granicy korowo-rdzeniowej i utrata funkcji nerek przed 30 r.ż. Wyróżnia się trzy podtypy kliniczne choroby: niemowlęcą, młodzieńczą i dorosłych. Pozanerkowe manifestacje nefronoftyzy, występujące u 10–20% chorych, to m.in. retinopatia barwnikowa, włóknienie wątroby i deformacje kostne. W pracy opisano troje dzieci z rozpoznaniem nefronoftyzy potwierdzonej badaniem genetycznym. Pierwszymi objawami choroby były niedokrwistość i moczenie nocne. Ze względu na pierwsze niespecyficzne objawy kliniczne, brak zmian w badaniu ogólnym moczu lub zmiany łagodne (zmniejszenie ciężaru właściwego moczu) oraz początkowo prawidłowy obraz nerek w badaniu ultrasonograficznym NPH zostało rozpoznane późno.

Distal renal tubular acidosis is a defect of acidification of urine in distal tubule. Full-blown form is characterized by polyuria, growth deficiency, nephrolithiasis or nephrocalcinosis. Mutations in genes encoding Cl-/HCO3 - exchanger (autosomal dominant) or H+-ATPase (autosomal recessive) are the most frequent in children.In a boy aged 2,5 years, healthy, with proper development, metabolic acidosis with hyperchloremia, hypokalaemia, normal glomerular filtration rate and alkaline urine was discovered during hospitalization because of pneumonia. USG showed normal length kidney with nephrocalcinosis type IIB. The family history revealed nephrocalcinosis on the part of the boy's father. He also had metabolic acidosis in blood gas test. Genetic test in a boy and his father showed mutation of SLC4A1(17q21-q22) gene encoding Cl-/HCO3 - exchanger. The boy was treated with 8,4% NaHCO3 - orally (1mEq/kg/24h) and KCl (0,3 mEq/kg/24h). We obtained normalization of blood gas test and potassium concentration.Every child, with accidentally discovered metabolic acidosis, even with normal development, should be diagnosed in case of renal tubular acidosis. Electrolytes, gas blood test, urinalysis and USG are needed in the closest family members of child with diagnosed renal tubular acidosis.

Congenital anomalies of the kidney and urinary tract (CAKUT) are a major cause of pediatric kidney failure. We performed a genome-wide analysis of copy number variants (CNVs) in 2, 824 cases and 21, 498 controls. Affected individuals carried a significant burden of rare exonic (i.e. affecting coding regions) CNVs and were enriched for known genomic disorders (GD). Kidney anomaly (KA) cases were most enriched for exonic CNVs, encompassing GD- CNVs and novel deletions ; obstructive uropathy (OU) had a lower CNV burden and an intermediate prevalence of GD-CNVs ; vesicoureteral reflux (VUR) had the fewest GD-CNVs but was enriched for novel exonic CNVs, particularly duplications. Six loci (1q21, 4p16.1-p16.3, 16p11.2, 16p13.11, 17q12, and 22q11.2) accounted for 65% of patients with GD-CNVs. Deletions at 17q12, 4p16.1- p16.3, and 22q11.2 were specific for KA ; the 16p11.2 locus showed extensive pleiotropy. Using a multidisciplinary approach, we identified TBX6 as a driver for the CAKUT subphenotypes in the 16p11.2 microdeletion syndrome.

Thromboembolic complications are found in 2-3% of children with nephrotic syndrome (NS); this increased risk is caused by hypovolemia, hemoconcentration, increased number and activity of platelets, hyperfibrinogenemia and loss of coagulation inhibitors. Risk is even higher in case of additional factors e.g. congenital thrombophilia.Girl with NS aged 17 11/12 years was admitted to hospital due to respiratory tract infection with cough and back pain. NS started 9 months earlier and she had two bouts of disease, and was treated only with prednisone (current dose - 60 mg/48h). On admission she was without any abnormalities on auscultation, with BP 111/65 mmHg, HR 80 bpm, satO2 99%. Lab results showed the increase of WBC 18.3×103/μL, D-dimers 23038 μg/L and proteinuria 900 mg/dL. Other values of examined parameters were in normal limits. Chest X-ray and ECG were also normal. Presumptive diagnosis of pulmonary embolism was made and the patient was given 1000IU of antithrombin III and nadroparine (2x90IU/kg/24h s.c.). In ECHO the occlusion of left pulmonary artery and preserved blood flow in right were revealed. In angioCT clot nearly filling lumen of left pulmonary artery, clot in intermediate part of right pulmonary artery, and focus of pulmonary infarction in 10th segment of left lung were found. Doppler USG of lower limb veins did not reveal thrombi or perforator vein incompetence. Treatment with nadroparine was continued, and rapid improvement of clinical condition and disappearance of pain and cough were observed. Mycophenolate mofetil was added, which resulted in subsidence of proteinuria. Rivaroxaban was used in prophylaxis of recurrences of thromboembolism. Tests for thrombophilia revealed factor V Leiden in patient.

BACKGROUND AND OBJECTIVES: Autosomal dominant polycystic kidney disease is the most common inheritable kidney disease, frequently thought to become symptomatic in adulthood. However, patients with autosomal dominant polycystic kidney disease may develop signs or symptoms during childhood, in particular hypertension. Although ambulatory BP monitoring is the preferred method to diagnose hypertension in pediatrics, data in children with autosomal dominant polycystic kidney disease are limited. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: Our retrospective multicenter study was conducted to collect ambulatory BP monitoring recordings from patients with autosomal dominant polycystic kidney disease age 1 cm per kidney and daytime hypertension (odds ratio, 1.70; 95% confidence interval, 1.21 to 2.4; P=0.002), nighttime hypertension (odds ratio, 1.31; 95% confidence interval, 1.05 to 1.63; P=0.02), or 24-hour hypertension (odds ratio, 1.39; 95% confidence interval, 1.08 to 1.81; P=0.01). Kidney length, expressed as SD score, was also significantly associated with nighttime hypertension (odds ratio, 1.23; 95% confidence interval, 1.06 to 1.42; P=0.10). CONCLUSIONS: These data indicate high prevalence of hypertension in children with autosomal dominant polycystic kidney disease starting at young ages. ispartof: CLINICAL JOURNAL OF THE AMERICAN SOCIETY OF NEPHROLOGY vol:13 issue:6 pages:874-883 ispartof: location:United States status: published

IgA nephropathy is the most common glomerulonephritis in the world. For diagnosis kidney biopsy is necessary.The aim of the study was assessment the significance of IgA, C3 and IgG deposits intensity and location in kidney childhood IgA nephropathy (IgAN) for the symptoms of the disease and the follow up.Study population consisted of 81 children, average 11,45±3,99 years. IgAN was recognized based on renal biopsy, performed 1,2±1,84, median 0,5 years after the onset. We used Oxford classification (OC) to assess the severity of histopatological lesions. In renal biopsy IgA and C3 deposits were found in immunofluorescence in mesangium or in vessels of glomeruli or both, and intensity was defined 0 to +4. We analyzed: proteinuria (mg/kg/day), hematuria, creatinine, GFR (according to Schwartz formula) two times, at the onset of the disease (OOD) and at the follow up (FU). Patients were treated with: ACEI/ARB or steroids alone or with imunossupresion drugs: azathioprine (AZA), cyclophosphamide (CYC), cyclosporine A (CsA), mycopnenolate mophetil (MMF). The follow up was 3,31±2,88 years. We divided the patients into two groups, depending on the intensity of IgA deposits: G1 n=29 (+1/+2), G2 n=52 (+3/+4); depending on the localizations of these deposits, we analyzed 3 groups: A n= 39 (mesangium), B n= 15 (glomeruli vessels), C n=27 (both) and depending on the kind of deposits we analyzed 4 groups: gr. a - n=30 (only IgA), gr. b - n=37 (IgA+C3), gr. c - n=5 (IgA+IgG) gr. d - n= 9 (IgA+IgG+C3).At OOD and FU we not found any differences in G1 vs G2 for: age, proteinuria, GFR and OC in renal biopsy; at FU GFR90 ml/ min/1,73 m2 FU was observed more frequently in G2 vs G1 (p=0,02). The differences in groups A,B,C and groups a,b,c,d were not found.Poor prognosis in childhood IgAN may also depend on the intensity of the deposits, irrespective of their location.

Introduction GDIgA1 (galactose deficient IgA1) plays a significant role in the pathogenesis of IgA nephropathy (IgAN) and Henoch-Schonlein nephritis (HSN). Aim of the study The aim of this study was to assess the relevance of serum GDIgA1 level as a prognostic marker in children with IgAN and HSN. Material and methods 41 children were included to the study group (15 IgAN, 26 HSN) and 22 to the control group. The following parameters were evaluated at baseline and endpoint: proteinuria, erythrocyturia, serum creatinine, serum IgA, GFR. A kidney biopsy was performed in all patients and evaluated according to the Oxford Classification (1 - present, 0 - absent: M - mesangial hypercellularity; E- endocapillary hypercellularity; S - segmental sclerosis/adhesion; T - tubular atrophy/interstitial fibrosis), and was calculated as the total score (sum of M, E, S, T). At the end of follow-up, the serum GDIgA1 concentration was measured. Results The serum GDIgA1 concentration in patients with IgAN and HSN was significantly higher than in the control group. No significant differences in mean proteinuria, erythrocyturia, GFR, MEST score, or GDIgA1 in serum, as well as the duration of follow-up between IgAN and HSN were observed. Baseline serum IgA concentration and time to kidney biopsy were significantly higher in children with IgAN than in children with HSN. We observed a positive correlation between GDIgA1 and IgA levels (r = 0.53), and GDIgA1 and serum creatinine levels (r = 0.5), as well as negative correlation between GDIgA1 and GFR (r = -0.37). Conclusions Serum GDIgA1 level may have a prognostic value in children with IgAN and HSN; however, to fully elucidate its clinical potential further studies performed in larger patient cohorts are required.

Oral colonization with Candida spp. is not synonymous with a systemic active infection. The aim of the study was to evaluate enzymatic activity of Candida strains isolated from the oral cavity in patients with nephrotic syndrome (NS) and to compare it with the activity determined in urine. We studied 32 children with NS and 26 control healthy children. Children with NS were treated with glucocorticosteroids, cyclosporin A, mycophenolate mofetil or azathioprine. In all children, API-ZYM enzymatic tests were performed to evaluate hydrolytic enzymes of Candida isolated from the oral cavity and in urine. Candida spp. were isolated from the oral cavity in 11 patients with NS (34.4%), all receiving immunosuppressive treatment. All strains produced valine arylamidase, 9 alpha-glucosidase (E16), and 9 N-acetyl-beta-glucosaminidase (E18). A positive correlation between the presence of Candida in the oral cavity and E16 and E18 enzymatic activity in both oral cavity and urine was found. A dose of cyclosporin A had an effect on the enzymatic activity (p0.05). We conclude that immunosuppressive treatment of NS in children may predispose to systemic Candida invasion. The results of this study suggest that oral candida infection should be monitored in children with nephrotic syndrome, particularly those treated with immunosuppressive agents.

Dent disease (DD) is a rare tubulopathy characterized by proximal tubular dysfunction leading to chronic kidney disease (CKD). The aim of the study was to characterize patients with DD in Poland. A retrospective analysis of a national cohort with genetically confirmed diagnosis. Of 24 males, all patients except one carried mutations in the CLCN5 gene; in one patient a mutation in the OCRL gene was disclosed. Molecular diagnosis was delayed 1 year on average (range 0–21 years). The most common features were tubular proteinuria (100%), hypercalciuria (87%), and nephrocalcinosis (56%). CKD (≤stage II) and growth deficiency were found in 45 and 22% of patients, respectively. Over time, a progression of CKD and persistence of growth impairment was noted. Subnephrotic and nephrotic proteinuria (20%) was found in most patients, but tubular proteinuria was assessed in only 67% of patients. In one family steroid-resistant nephrotic syndrome prompted a genetic testing, and reverse phenotyping. Five children (20%) underwent kidney biopsy, and two of them were treated with immunosuppressants. Hydrochlorothiazide and angiotensin-converting enzyme inhibitors were prescribed for a significant proportion of patients (42 and 37.5%, respectively), while supplemental therapy with phosphate, potassium, vitamin D (12.5% each), and alkali (4.2%) was insufficient, when compared to the percentages of patients requiring repletion. We found CLCN5 mutations in the vast majority of Polish patients with DD. Proteinuria was the most constant finding; however, tubular proteins were not assessed commonly, likely leading to delayed molecular diagnosis and misdiagnosis in some patients. More consideration should be given to optimize the therapy.

Aim Evaluation of mean blood pressure values, ambulatory arterial stiffness index (AASI), pulse pressure (PP), blood pressure variability (BPV), and circadian blood pressure rhythm using ambulatory blood pressure monitoring (ABPM) in children with IgA nephropathy and Henoch-Schonlein nephropathy (IgAN/HSN). Material and methods In 48 children (29 with IgAN, 19 with HSN) aged 14.04 ± 3.76 years, we evaluated retrospectively 24-hour systolic and diastolic BP (24hSBP, 24hDBP), AASI, PP, systolic and diastolic BPV, and nocturnal BP dip by ABPM, body mass index (BMI) Z-score, medications, and biochemical parameters. The control group (CG) consisted of 20 healthy children aged 13.36 ± 4.12 years. Results AASI was 0.369 ± 0.100 in IgAN, 0.346 ± 0.148 in HSN, and 0.300 ± 0.067 in the CG; AASI was significantly (p = 0.009) higher in IgAN vs. CG. PP was higher (P = 0.04) in IgAN vs. HSN. Based on ABPM data, poorly-controlled hypertension was found in 14 of 22 patients (63.6%) with previously diagnosed hypertension. No differences in BPV or nocturnal BP dip were found between the groups. In all children with IgAN/HSN, 24hDBP correlated significantly with proteinuria, cholesterol, triglycerides, and prednisone dose; BMI Z-score correlated with SBPV, DBPV, and PP. Conclusions 1. Children with IgAN have higher arterial stiffness compared to healthy peers. 2. In children with IgAN/HSN, proteinuria and hyperlipidemia are risk factors for elevated diastolic blood pressure, while obesity is a risk factor for increased blood pressure variability and pulse pressure. 3. Pediatric patients with IgAN/HSN require regular ABPM evaluation to allow for early detection of poor pharmacological control of hypertension. .

Studies suggest that renalase, a renal catecholamine-inactivating enzyme, plays a major role in the pathogenesis of kidney and cardiovascular diseases in adults. This study seeks to determine the role of renalase in children with glomerular kidney diseases. We evaluated the serum renalase, arterial stiffness, intima-media thickness, blood pressure, and clinical and biochemical parameters in 78 children (11.9 ± 4.6 years of age) with glomerulopathies such as idiopathic nephrotic syndrome (40 cases), IgA nephropathy (12 cases), Henoch-Schönlein nephropathy (12 cases), and other glomerulopathies (14 cases). The control group consisted of 38 healthy children aged 11.8 ± 3.3 years. The mean renalase was 25.74 ± 8.94 μg/mL in the glomerulopathy group, which was not significantly different from the 27.22 ± 5.15 in the control group. The renalase level did not differ among various glomerulopathies either. However, proteinuric patients had a higher renalase level than those without proteinuria (28.43 ± 11.71 vs. 24.05 ± 6.23, respectively; p = 0.03). In proteinuric patients, renalase correlated with daily proteinuria. In the entire glomerulopathy group, renalase correlated with age, systolic central blood pressure (BP), diastolic peripheral and central BP, mean peripheral and central BP; peripheral diastolic BP Z-score, glomerular filtration rate, cholesterol, triglycerides, and pulse wave velocity. We conclude that in children with glomerulopathies renalase, although basically not enhanced, may underlie blood pressure elevation and arterial damage.

International audience; Background: The DiGeorge syndrome, the most common of the microdeletion syndromes, affects multiple organs, including the heart, the nervous system, and the kidney. It is caused by deletions on chromosome 22q11.2; the genetic driver of the kidney defects is unknown.Methods: We conducted a genomewide search for structural variants in two cohorts: 2080 patients with congenital kidney and urinary tract anomalies and 22,094 controls. We performed exome and targeted resequencing in samples obtained from 586 additional patients with congenital kidney anomalies. We also carried out functional studies using zebrafish and mice.Results: We identified heterozygous deletions of 22q11.2 in 1.1% of the patients with congenital kidney anomalies and in 0.01% of population controls (odds ratio, 81.5; P=4.5×10-14). We localized the main drivers of renal disease in the DiGeorge syndrome to a 370-kb region containing nine genes. In zebrafish embryos, an induced loss of function in snap29, aifm3, and crkl resulted in renal defects; the loss of crkl alone was sufficient to induce defects. Five of 586 patients with congenital urinary anomalies had newly identified, heterozygous protein-altering variants, including a premature termination codon, in CRKL. The inactivation of Crkl in the mouse model induced developmental defects similar to those observed in patients with congenital urinary anomalies.Conclusions: We identified a recurrent 370-kb deletion at the 22q11.2 locus as a driver of kidney defects in the DiGeorge syndrome and in sporadic congenital kidney and urinary tract anomalies. Of the nine genes at this locus, SNAP29, AIFM3, and CRKL appear to be critical to the phenotype, with haploinsufficiency of CRKL emerging as the main genetic driver. (Funded by the National Institutes of Health and others.).

Studies suggest that renalase, a renal catecholamine-inactivating enzyme, plays a major role in the pathogenesis of kidney and cardiovascular diseases in adults. This study seeks to determine the role of renalase in children with glomerular kidney diseases. We evaluated the serum renalase, arterial stiffness, intima-media thickness, blood pressure, and clinical and biochemical parameters in 78 children (11.9 ± 4.6 years of age) with glomerulopathies such as idiopathic nephrotic syndrome (40 cases), IgA nephropathy (12 cases), Henoch-Schonlein nephropathy (12 cases), and other glomerulopathies (14 cases). The control group consisted of 38 healthy children aged 11.8 ± 3.3 years. The mean renalase was 25.74 ± 8.94 μg/mL in the glomerulopathy group, which was not significantly different from the 27.22 ± 5.15 in the control group. The renalase level did not differ among various glomerulopathies either. However, proteinuric patients had a higher renalase level than those without proteinuria (28.43 ± 11.71 vs. 24.05 ± 6.23, respectively; p = 0.03). In proteinuric patients, renalase correlated with daily proteinuria. In the entire glomerulopathy group, renalase correlated with age, systolic central blood pressure (BP), diastolic peripheral and central BP, mean peripheral and central BP; peripheral diastolic BP Z-score, glomerular filtration rate, cholesterol, triglycerides, and pulse wave velocity. We conclude that in children with glomerulopathies renalase, although basically not enhanced, may underlie blood pressure elevation and arterial damage.

Oral colonization with Candida spp. is not synonymous with a systemic active infection. The aim of the study was to evaluate enzymatic activity of Candida strains isolated from the oral cavity in patients with nephrotic syndrome (NS) and to compare it with the activity determined in urine. We studied 32 children with NS and 26 control healthy children. Children with NS were treated with glucocorticosteroids, cyclosporin A, mycophenolate mofetil or azathioprine. In all children, API-ZYM enzymatic tests were performed to evaluate hydrolytic enzymes of Candida isolated from the oral cavity and in urine. Candida spp. were isolated from the oral cavity in 11 patients with NS (34.4%), all receiving immunosuppressive treatment. All strains produced valine arylamidase, 9 alpha-glucosidase (E16), and 9 N-acetyl-beta-glucosaminidase (E18). A positive correlation between the presence of Candida in the oral cavity and E16 and E18 enzymatic activity in both oral cavity and urine was found. A dose of cyclosporin A had an effect on the enzymatic activity (p < 0.05). We conclude that immunosuppressive treatment of NS in children may predispose to systemic Candida invasion. The results of this study suggest that oral candida infection should be monitored in children with nephrotic syndrome, particularly those treated with immunosuppressive agents.

In the version of this article initially published, affiliation 38 incorrectly read “ICNU-Nephrology and Urology Department, Barcelona, Spain”; “Renal Division, Hospital Clinic, IDIBAPS, University of Barcelona, Barcelona, Spain” is the correct affiliation. The error has been corrected in the HTML and PDF versions of the article.

Henoch-Schönlein purpura (HSP) is the most common pediatric autoimmune vasculitis. Gastrointestinal symptoms of HSP including abdominal pain, diarrhea, and vomiting may precede skin changes by several days. We present diagnostic challenges in two adolescents with HSP and severe abdominal symptoms necessitating surgical intervention before the development of skin changes.A 15-year old boy with 7 day history of abdominal pain, and bloody vomiting (1-2 x per day) without diarrhea. A suspicion of acute appendicitis was raised and the boy was operated on the 7th day since the initial symptoms. The appendix showed some reactive inflammation and was removed during laparotomy which also revealed enlarged mesenteric lymph nodes and a modest amount of fluid in the pelvic cavity. During the first day after the surgery, skin changes typical for HSP developed on lower limbs and buttocks.A 12-year old girl with 7 day history of abdominal pain, without diarrhea or vomiting. On the day of admission hemorrhagic rash appeared on lower limbs. Laparotomy was performed on 14th day after onset of abdominal pain - large amounts of serous, blood-stained fluid, massive dilation of small intestine with ecchymoses in mucous membrane, segmental infiltration and stiffening of intestinal wall were found. Normal appendix was removed.Severe abdominal symptoms may precede skin changes in children with HSP, resulting in diagnostic and therapeutic challenges. When considering laparotomy in children with an atypical "acute abdomen" presentation, other manifestations of HSP should be sought.

The aim of the present study was to quantify the effects of treatment of children with Henoch-Schönlein nephritis (HSN) evaluated on the basis of kidney biopsy findings. Data were analyzed from 32 patients with HSN (mean age 9.3 ± 3.5 years, 19 with nephrotic syndrome/nephrotic proteinuria NS/NP, 13 with nephritic syndrome NphS), in whom the diagnosis was confirmed by kidney biopsy. Patients received immunosuppressive treatment (azathioprine or cyclophosphamide) and/or steroids and renoprotection according to a defined protocol. Patients were referred to a specific treatment protocol selected on the basis of clinical symptoms of nephropathy (NS/NP or NphS) and histopathological grade according to the WHO classification. Grade I-II changes were defined as mild HSN, and grade III-V WHO as severe HSN. The follow-up kidney biopsy was performed upon obtaining parental consent in 17 children. Following treatment, proteinuria resolved in 78 % children with mild HSN and 87 % children with severe HSN. In kidney biopsy, histological improvement was seen in 59 % children and no worsening in 35 %. We conclude that a flexible treatment protocol related to clinical symptoms and histological staging may contribute to a reduction of proteinuria and a delay in disease progression in children with HSN.

Myelomeningocele (MMC) results from a failure of normal neural tube fusion in early fetal development. Retrospective, observational study of medical data of 54 children treated in Pediatric Nephrology and Urology Clinics for five years was performed. The following data were analyzed: serum creatinine, eGFR, urine analysis, renal scintigraphy (RS), renal ultrasound, and urodynamics. Mean age of studied population: 12.3 years, median of eGFR at the beginning and at the end of survey was 110.25 and 116.5 mL/min/1.73 m2 accordingly. Median of frequency of urinary tract infections (fUTI): 1.2 episodes/year. In 24 children: low-pressure, in 30 children: high-pressure bladder was noted. Vesicouretral reflux (VUR) was noted in 23 children (42.6%). fUTI were more common in high-grade VUR group. High-grade VURs were more common in group of patients with severe renal damage. At the end of the survey 11.1% children were qualified to higher stages of chronic kidney disease. Renal parenchyma damage progression in RS was noted in 22.2% children. Positive VUR history, febrile recurrent UTIs, bladder wall trabeculation, and older age of the patients constitute risk factors of abnormal renal scans. More than 2.0 febrile, symptomatic UTIs annually increase by 5.6-fold the risk of severe renal parenchyma damage after five years.

The aim of this retrospective study was to assess the usefulness of potential predictors of poor prognosis in IgA nephropathy in children. The study population consisted of 55 children aged 11 ± 4 years, diagnosed on the basis of the Oxford classification and MEST score of kidney biopsy findings. Proteinuria, glomerular filtration rate (GFR), and the IgA/C3 serum ratio were assessed in all patients twice: at onset and at follow-up. The patients were treated with steroids, immunosuppressive drugs, and/or angiotensin-converting enzyme inhibitors. Follow-up was at 3.9 ± 2.9 (median 2.7) years. The patients were subdivided into two groups: with GFR

IgA nephropathy (IgAN) is the most common form of glomerulonephritis in pediatric population. The clinical presentation of the disease in children ranges from microscopic hematuria to end-stage kidney disease. The aim of the study was to retrospectively assess clinical and kidney biopsy features in children with IgAN. We assessed a cohort of 140 children, 88 boys, 52 girls with the diagnosis of IgAN in the period of 2000–2015, entered into the national Polish pediatric IgAN registry. The assessment included the following: proteinuria, hematuria, glomerular filtration rate (GFR), arterial blood pressure, and the renal pathological changes according to the Oxford classification and crescents formation, as modifiable and unmodifiable risk factors. The incidence of IgAN in Poland was set at 9.3 new cases per year. The mean age at onset of IgAN was 11.9 ± 4.3 years, and the most common presentation of the disease was the nephritic syndrome, recognized in 52 % of patients. Kidney biopsy was performed, on average, 1.3 ± 2.0 years after onset of disease. Based on the ROC analysis, a cut-off age at onset of disease for GFR 13.9 years) compared with Gr 2 (

The aim of the present study was to quantify the effects of treatment of children with Henoch-Schonlein nephritis (HSN) evaluated on the basis of kidney biopsy findings. Data were analyzed from 32 patients with HSN (mean age 9.3 ± 3.5 years, 19 with nephrotic syndrome/nephrotic proteinuria NS/NP, 13 with nephritic syndrome NphS), in whom the diagnosis was confirmed by kidney biopsy. Patients received immunosuppressive treatment (azathioprine or cyclophosphamide) and/or steroids and renoprotection according to a defined protocol. Patients were referred to a specific treatment protocol selected on the basis of clinical symptoms of nephropathy (NS/NP or NphS) and histopathological grade according to the WHO classification. Grade I–II changes were defined as mild HSN, and grade III–V WHO as severe HSN. The follow-up kidney biopsy was performed upon obtaining parental consent in 17 children. Following treatment, proteinuria resolved in 78 % children with mild HSN and 87 % children with severe HSN. In kidney biopsy, histological improvement was seen in 59 % children and no worsening in 35 %. We conclude that a flexible treatment protocol related to clinical symptoms and histological staging may contribute to a reduction of proteinuria and a delay in disease progression in children with HSN.

Streszczenie Zespol hemolityczno-mocznicowy (ZHM) jest to mikroangiopatia zakrzepowa z charakterystyczną triadą objawow: niedokrwistością hemolityczną, maloplytkowością i ostrą niewydolnością nerek. U 90% dzieci ZHM rozwija sie najcześciej po infekcji jelitowej wywolanej przez E. coli produkującą werotoksyne. U pozostalych 10%, bez poprzedzającej biegunki, rozpoznaje sie atypowy ZHM. Cel Celem pracy byla ocena czestości wystepowania i przebiegu klinicznego ZHM u 140 dzieci hospitalizowanych w latach 1971–2010 w Katedrze i Klinice Pediatrii i Nefrologii WUM. Material i Metody Przeanalizowano 2 grupy chorych: hospitalizowanych w latach 1971–1992 (grupa I; n=94) i 1993–2010 (grupa II; n=46). Podzial uwzglednial zmiane sposobu terapii, gdyz od roku 1993 stosowano plazmaferezy w leczeniu atypowych i ciezko przebiegających ZHM. Wyniki Dzieci z grupy I byly istotnie mlodsze (1,43 ± 1,97 roku) niz z grupy II (4,48 ± 4,46 roku); p Wniosek Leczenie plazmaferezami i wlewami osocza poprawilo rokowanie u chorych i zmniejszylo koniecznośc stosowania leczenia nerkozastepczego u dzieci z ZHM.

The aim of the study was to determine whether an elevated IgA level at the time of the diagnosis of IgA nephropathy has an effect on the severity of kidney biopsy findings and long-term outcomes in children. We retrospectively studied 89 children with IgA nephropathy who were stratified into Group 1- elevated serum IgA and Group 2 – normal serum IgA at baseline. The level of IgA, proteinuria, hematuria, glomerular filtration rate (GFR) and hypertension (HTN) were compared at baseline and after the end of the follow-up period of 4.0 ± 3.1 years. Kidney biopsy findings were evaluated using the Oxford classification. The evaluation of treatment included immunosuppressive therapy and renoprotection with angiotensin converting-enzyme inhibitor (ACEI) or angiotensin II receptor blocker (ARB), or no treatment. The elevated serum IgA was found in 46 (52 %) patients and normal serum IgA level was found in 43 (48 %) patients. No differences were found between the two groups regarding the mean age of patients, proteinuria, and the number of patients with reduced GFR or HTN at baseline. In kidney biopsy, mesangial proliferation and segmental sclerosis were significantly more common in Group 1 compared with Group 2 (p < 0.05). Immunosuppressive therapy was used in 67 % children in Group 1 and 75 % children in Group 2. The Kaplan-Meier survival curves for renal function (with normal GFR) and persistent proteinuria did not differ significantly depending on the serum IgA level at baseline. We conclude that in IgA nephropathy the elevated serum IgA at baseline may be associated with mesangial proliferation and segmental sclerosis contribute to glomerulosclerosis, but has no effect on the presence of proteinuria or on the worsening of kidney function during several years of disease course.

Background Diabetes and Nephrotic syndrome (NS) promote plaque-related gingivitis and yeast-like fungal infections. The study assesses the impact of Candida spp. and general disease- or treatment-related factors on plaque-related gingivitis severity in children and adolescents with Nephrotic syndrome /diabetes. Methods Body mass index (BMI), BMI standard deviation score, and oral cavity (Plaque Index – PLI, Gingival Index – GI, mucosa status, presence and Candida enzymatic activity) were assessed in 96 patients (32 with NS: 30- immunosuppressive treatment, 35 - type 1 diabetes, and 29 generally healthy), aged; 3–18 years. Laboratory included cholesterol and triglyceride measurements; in diabetic subjects– glycated haemoglobin, in NS: total protein, albumin, creatinine, haemoglobin, haematocrit, white cell count, urinary protein excretion. Medical records supplied information on disease duration and treatment. A statistical analysis was performed; Kendall Tau coefficient, chi-square test, t-test, and multiple regression analysis ( P 1 drug, drug doses, treatment duration, lipid disorders, and BMI; in diabetes, with blood glucose and glycated haemoglobin >8%. Conclusion Poor hygiene control is the main cause of gingivitis. Gingivitis severity is most likely related to age, lipid disorders and increase in body mass. Candida spp., in uncompensated diabetes and in those using immunosuppressive treatment, might intensify plaque-related gingivitis.

BACKGROUND: There is a need for early identification of children with immunoglobulin A nephropathy (IgAN) at risk of progression of kidney disease. METHODS: Data on 261 young patients [age 90 ml/min/1.73 m(2)) at presentation had a significantly high probability of proteinuria remission during follow-up and a higher remission rate following treatment with corticosteroid and/or immunosuppressive therapy. CONCLUSION: This new statistical approach has identified clinical and histological risk factors associated with outcome in children and young adults with IgAN.

The aim of this study was to evaluate the usefulness of serum immunoglobulin A/complement factor 3 (IgA/C3) ratio for predicting histological severity of kidney lesions in children with IgA nephropathy (IgAN) based on World Health Organization (WHO) and the Oxford classification (OC).We studied 89 children with IgAN with a mean age of 11.38 ± 4.1 years (range 2-18 years). Based on available medical records, we retrospectively evaluated clinical data, IgA/C3 ratio, and kidney biopsy findings using the five-grade WHO classification and the OC The mesangial hypercellularity (M), endocapillary hypercellularity (E), segmental sclerosis (S), tubular atrophy/interstitial fibrosis (T) (MEST) score (absent = 0, present = 1) calculated as the sum of M+E+S+T ranging from 0 to 4.Mean IgA/C3 ratio values were significantly higher (P0.05) in patients with M1, S1, and T1 compared with M0, S0, and T0, respectively (P0.05); there were no differences in the WHO classification. We found a significant positive correlation between the IgA/C3 ratio and proteinuria (r = 0.24) and determined optimal cutoff values of the IgA/C3 ratio, with a corresponding confidence interval for specific MEST scores.The IgA/C3 ratio in children with IgAN may be a useful marker of the severity of lesions found in kidney biopsy as evaluated using the OC.

Assessment of vitamin D status in children with selected renal diseases based on serum 25OHD3 level taking into consideration type of kidney disease, vitamin D supplementation and season of the year.Retrospective analysis of 127 children aged from 0.6 to 17.7 years, median 9.5 [24 with risk status of urolithiasis (RSU), 29 with urolithiasis, 15 with glomerulonephritis, 59 with idiopathic nephrotic syndrome (INS)] was performed. Serum concentrations of 25OHD3, 1,25(OH)2 D3, calcium, and phosphorus were measured. The correlation of 25OHD3 with the type of kidney disease, supplementation of vitamin D, seasons, gender, age, and the dose of glucocorticosteroids (in children with glomerulopathies) were analyzed.In all children serum concentration of 25OHD3 from 4.3 to 72.6 ng/mL (median 21.1 ng/mL). The deficiency or insufficiency of vitamin D were observed in 55 (43.3%) analyzed children with kidney diseases. The deficiency or insufficiency of vitamin D were observed in 49.1% children with RSU and urolithiasis, and in 39.2% with glomerulonephritis and INS: in 36% children supplemented with vitamin D and 54% not supplemented (NS). In winter, 25OHD3 serum concentration was significantly higher in children supplemented with vitamin D compared to not supplemented [median 21.5 ng/mL vs 16.5 ng/mL (p0.05)]. There were no significant differences in serum concentrations of 25OHD3 , 1,25(OH)2 D3 , calcium, phosphorus and calcium x phophorus product depending on type of kidney disease and gender. The significant negative correlation was found between 25OHD3 and patients' age (r=-0.26 p0.01) and between calcium (r=0.31, p0.05) and calcium x phosphorus in children supplemented with vitamin D (r=0.28, p0.05).Our results suggest the necessity to develop new strategies in vitamin D supplementation in children with kidney diseases. Futher studies shoud also be performed to evaluate their efficiency.

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.