A case of Dent disease type 2 with large deletion of OCRL diagnosed after close examination of a school urinary test.

A 7-year-old boy visited our hospital for a detailed examination of proteinuria identified in a school urinary test. He had short stature, misaligned teeth, and mild intellectual disability. A urinary examination identified mild proteinuria and extremely high levels of beta-2 microglobulin. On blood examination, his protein, albumin, and creatinine levels were found to be normal; however, his lactate dehydrogenase and creatinine phosphokinase levels were slightly elevated. Upon histological examination, no abnormalities in glomeruli or tubules were found. Considering these results, we diagnosed our patient with Dent disease type 2 (DD2). Although the whole exome sequencing revealed large deletion of OCRL, which was seen only in Lowe syndrome and not in DD2 previously, our final diagnosis for the patient is DD2. A phenotypic continuum exists between Dent disease and Lowe syndrome, and several factors modify the phenotypes caused by defects in OCRL. Although patients have thus far been diagnosed with DD2 or Lowe syndrome on the basis of their symptoms, accumulation and analysis of cases with OCRL defects may hereafter enable more accurate diagnoses.

Cancer After Pediatric Kidney Transplantation: A Long-term Single-center Experience in Japan.

BACKGROUND: The cancer incidence, types, and risk factors after pediatric kidney transplantation (KT) have been reported in the United States, Canada, Europe, Australia, and New Zealand. However, no information is available about cancer in pediatric KT recipients in Asian countries. METHODS: Children aged <20 y who underwent initial KT from 1983 to 2016 were analyzed. We compared the cancer incidence with that in the general Japanese population using standardized incidence ratio and examined posttransplant cancer risk using Cox proportional hazards models. RESULTS: A total of 356 children (median age, 11.7 y; interquartile range, 5.0-17.6) received KT with a follow-up period of 4466 person-years. The median age of cancer onset was 18.5 y (interquartile range, 8.0-32.3), and 13 cancers occurred in 12 patients (3.4%). Two patients died from cancer. The most common cancers were posttransplant lymphoproliferative disorders (PTLDs) (38.5%). The median time to PTLD and non-PTLD diagnosis after KT was 0.6 and 16.4 y, respectively. There was no occurrence of skin cancer. The posttransplant cancer incidence was 9.9 times higher than that in the general age-matched population (standardized incidence ratio = 9.9; 95% confidence interval, 4.80-18.39). The cumulative cancer incidence was 5.3% in 20 y after KT, which is lower than that reported in previous studies. We could not identify any risk factors for all cancer after KT in all patients, whereas subgroup analysis in 264 patients with available data of recipient Epstein-Barr virus serological status showed that recipient Epstein-Barr virus-negative serology was an independent risk factor for cancer development. CONCLUSIONS: The incidence of cancer is higher in Japanese pediatric KT recipients than in the general population. The cumulative incidence of cancer after KT was lower in our population than that previously reported. This may be because there was no skin cancer observed in the Japanese pediatric KT recipients in our study.

Degree of foot process effacement in patients with genetic focal segmental glomerulosclerosis: a single-center analysis and review of the literature.

Determining the cause of focal segmental glomerulosclerosis (FSGS) has crucial implications for evaluating the risk of posttransplant recurrence. The degree of foot process effacement (FPE) on electron micrographs (EM) of native kidney biopsies can reportedly differentiate primary FSGS from secondary FSGS. However, no systematic evaluation of FPE in genetic FSGS has been performed. In this study, percentage of FPE and foot process width (FPW) in native kidney biopsies were analyzed in eight genetic FSGS patients and nine primary FSGS patients. All genetic FSGS patients showed segmental FPE up to 38% and FPW below 2000 nm, while all primary FSGS patients showed diffuse FPE above 88% and FPW above 3000 nm. We reviewed the literature which described the degree of FPE in genetic FSGS patients and identified 38 patients with a description of the degree of FPE. The degree of FPE in patients with mutations in the genes encoding proteins associated with slit diaphragm and cytoskeletal proteins was varied, while almost all patients with mutations in other FSGS genes showed segmental FPE. In conclusion, the present study suggests that the degree of FPE in native kidney biopsies may be useful for differentiating some genetic FSGS patients from primary FSGS patients.

Amount and selectivity of proteinuria may predict the treatment response in post-transplant recurrence of focal segmental glomerulosclerosis: a single-center retrospective study.

BACKGROUND: Primary focal segmental glomerulosclerosis (FSGS) frequently recurs after kidney transplantation and is associated with poor graft survival. To date, few studies have investigated predictive factors for treatment responses in recurrent FSGS. METHODS: We retrospectively analyzed 16 patients who were < 16 years at the age of onset and had post-transplant recurrence of FSGS from 1993 to 2018. Patients who achieved complete remission or partial remission after initiating therapy for recurrent FSGS were defined as responders. We compared several clinical characteristics between responders and non-responders. Time to remission was also analyzed. RESULTS: Ten patients were responders, and six patients were non-responders. Univariate analysis showed that responders had a significantly lower amount of maximum proteinuria at the time of recurrence (P = 0.015) and more highly selective proteinuria (P = 0.013) than non-responders. The time to remission from initiation of therapy was 2 months (interquartile range 0.2-4.4). In all responders, except for one patient, remission was achieved within 6 months. CONCLUSIONS: Therapeutic responses may be predicted by examining the amount and selectivity of proteinuria at the time of recurrence. Further studies with larger numbers of patients are clearly required to validate these findings.

Valganciclovir prophylaxis for cytomegalovirus infection in pediatric kidney transplant recipients: a single-center experience.

BACKGROUND: There are two approaches for treating cytomegalovirus (CMV) infection occurring after kidney transplantation (KTx). One is preemptive therapy in which treatment is started after confirming positive CMV antigenemia using periodic antigenemia assay. The other approach is prophylactic therapy in which oral valganciclovir (VGCV) is started within 10 days after KTx and continued for 200 days. The Transplantation Society guidelines recommend prophylactic therapy for high-risk (donor's CMV-IgG antibody positive and recipient's negative) pediatric recipients. However, the adequate dose and side effects of VGCV are not clear in children, and there is no sufficient information about prophylaxis for Japanese pediatric recipients. METHODS: A single-center retrospective analysis was conducted on case series of high-risk pediatric patients who underwent KTx and received oral VGCV prophylaxis at the Department of Pediatric Nephrology, Tokyo Women's Medical University, between August 2018 and March 2019. Data were collected using medical records. RESULTS: The dose of administration was 450 mg in all the study patients (n = 5). Reduction or discontinuation was required in four of five patients due to adverse events, which included neutropenia in one patient, anemia in two patients, and neutropenia and digestive symptoms in one patient. Late-onset CMV disease occurred in all patients. No seroconversion was observed during prophylaxis. CONCLUSIONS: Our preliminary study suggests that the dosage endorsed by The Transplantation Society may be an overdose for Japanese pediatric recipients. Further studies are required to examine the safety and efficacy of VGCV prophylaxis in Japanese pediatric recipients.

Any modality of renal replacement therapy can be a treatment option for Joubert syndrome.

Joubert syndrome (JS) is an inherited ciliopathy characterized by a distinctive cerebellar and brain stem malformation which is known as the "molar tooth sign" on axial brain images, hypotonia, and developmental delay. Approximately 25-30% of patients with JS have kidney disease and many of them progress to end-stage kidney disease (ESKD). However, there are few reports on the outcomes of renal replacement therapy (RRT) in patients with JS and ESKD. In this study, we clarified the clinical features, treatment, and outcomes of patients with JS who underwent RRT. We retrospectively analyzed the medical records and clinical characteristics of 11 patients with JS who underwent RRT between June 1994 and July 2019. Data are shown as the median (range). Gene analysis was performed in 8 of the 11 cases, and CEP290 mutations were found in four patients, two had TMEM67 mutations, one had a RPGRIP1L mutation, and one patient showed no mutation with the panel exome analysis. Complications in other organs included hydrocephalus in two cases, retinal degeneration in eight cases, coloboma in one case, liver diseases in four cases, and polydactyly in one case. Peritoneal dialysis (PD) was introduced in seven cases, with a median treatment duration of 5.4 (3.4-10.7) years. Hemodialysis was performed using arteriovenous fistula in two cases, and kidney transplantation was performed 9 times in eight cases. Only one of the grafts failed during the observation period of 25.6 (8.2-134.2) months. The glomerular filtration rate at the final observation was 78.1 (41.4-107.7) mL/min/1.73 m2. The median age at the final observation was 13.4 (5.6-25.1) years, and all patients were alive except one who died of hepatic failure while on PD. Any type of RRT modality can be a treatment option for patients with JS and ESKD.

Morphologic Analysis of Urinary Podocytes in Focal Segmental Glomerulosclerosis.

Background: The development of glomerulosclerosis in FSGS is associated with a reduction in podocyte number in the glomerular capillary tufts. Although it has been reported that the number of urinary podocytes in FSGS exceeds that of minimal-change nephrotic syndrome, the nature of events that promote podocyte detachment in FSGS remains elusive. Methods: In this study, we provide detailed, morphologic analysis of the urinary podocytes found in FSGS by examining the size of the urinary podocytes from patients with FSGS, minimal-change nephrotic syndrome, and GN. In addition, in urinary podocytes from patients with FSGS and minimal-change nephrotic syndrome, we analyzed podocyte hypertrophy and mitotic catastrophe using immunostaining of p21 and phospho-ribosomal protein S6. Results: The size of the urinary podocytes was strikingly larger in samples obtained from patients with FSGS compared with those with minimal-change nephrotic syndrome and GN (P=0.008). Urinary podocytes from patients with FSGS had a higher frequency of positive immunostaining for p21 (P<0.001) and phospho-ribosomal protein S6 (P=0.02) than those from patients with minimal-change nephrotic syndrome. Characteristic features of mitotic catastrophe were more commonly observed in FSGS than in minimal-change nephrotic syndrome urinary samples (P=0.001). Conclusions: We posit that the significant increase in the size of urinary podocytes in FSGS, compared with those in minimal-change nephrotic syndrome, may be explained by hypertrophy and mitotic catastrophe.

Chronic Active Antibody-Mediated Rejection with Linear IgG Deposition on Glomerular Capillaries in a Kidney Transplant Recipient.

Glomerular IgG deposition is rarely observed in antibody-mediated rejection. Here, we report chronic active antibody-mediated rejection with linear IgG deposition on glomerular capillary walls in a pediatric kidney transplant recipient. A 6-year-old boy with bilateral renal hypoplasia underwent preemptive deceased-donor kidney transplantation. Five years after the transplantation, an allograft biopsy revealed chronic active antibody-mediated rejection with diffuse linear IgG deposition on glomerular capillaries. Anti-glomerular basement membrane antibody, donor-specific anti-human leukocyte antigen (HLA) antibodies, and anti-angiotensin II type 1 receptor antibody were negative. A multiplex antibody assay identified anti-major histocompatibility complex class I chain-related molecule A antibody. Additionally, a single-antigen bead assay identified autoantibodies to 12 non-HLA antigens, including vimentin and glutathione S-transferase theta-1. To investigate whether IgG autoantibodies in the patient's serum bind to antigens on glomerular capillaries, we incubated the patient's serum with 0-h biopsy specimens of tissue donated to the patient and a control subject, both obtained immediately after nephrectomy from respective donors. IgG signals were observed in neither patient nor control samples. Nevertheless, linear IgG deposition may be explained by the binding of autoantibodies to non-HLA antigens that are usually hidden and only exposed via severe endothelial cell injury. Further studies are needed to confirm the significance of non-HLA antibodies in glomerular IgG deposition.

Rapid progression to end-stage renal disease in a child with IgA-dominant infection-related glomerulonephritis associated with parvovirus B19.

Parvovirus B19 (PVB19) has been known to cause acute glomerulonephritis and nephrotic syndrome with various renal histologic patterns, such as endocapillary glomerulonephritis and collapsing glomerulopathy. Remission is achieved spontaneously or by treatment with steroid and/or immunosuppressants in most patients, except those with sickle cell anemia or two APOL1 risk alleles. In this study, we report the case of a previously healthy 5-year-old boy with infection-related glomerulonephritis (IRGN) associated with PVB19 that progressed to end-stage renal disease (ESRD). He presented with macrohematuria, nephrotic-range proteinuria, and progressive renal dysfunction despite treatment with methylprednisolone pulse therapy, plasmapheresis, and intravenous immunoglobulin. The kidney biopsy specimens exhibited endocapillary infiltration and mesangiolysis with cellular crescent formation. Immunofluorescence analysis revealed that IgA was dominantly positive in the glomeruli, with some co-localized with KM55, which is a specific monoclonal antibody for galactose-deficient IgA1 (Gd-IgA1). The intensity of the KM55 signal in the present patient was weaker than that in patients with IgA nephropathy. To our knowledge, this is the first report of IRGN associated with PVB19 that progressed to ESRD without any underlying diseases. Further investigations are needed to determine the significance of IgA and Gd-IgA1 deposition in IRGN associated with PVB19.

Incomplete cryptic splicing by an intronic mutation of OCRL in patients with partial phenotypes of Lowe syndrome.

Mutations of OCRL cause Lowe syndrome, which is characterised by congenital cataracts, infantile hypotonia with mental retardation, and renal tubular dysfunction and Dent-2 disease, which only affects the kidney. While few patients with an intermediate phenotype between these diseases have been reported, the mechanism underlying variability in the phenotype is unclear. We identified an intronic mutation, c.2257-5G>A, in intron 20 of OCRL in an older brother with atypical Lowe syndrome without eye involvement and a younger brother with renal phenotype alone. This mutation created a splice acceptor motif that was accompanied by a cryptic premature termination codon at the junction of exons 20 and 21. The mutation caused incomplete alternative splicing, which created a small amount of wild-type transcript and a relatively large amount of alternatively spliced transcript with a premature termination codon. In the patients' cells, the alternatively spliced transcript was degraded by nonsense-mediated decay and the wild-type transcript was significantly decreased, but not completely depleted. These findings imply that an intronic mutation creating an incomplete alternative splicing acceptor site results in a relatively low level of wild-type OCRL mRNA expression, leading to partial phenotypes of Lowe syndrome.

Renal hypoplasia can be the cause of membranous nephropathy-like lesions.

BACKGROUND: Renal hypoplasia (RH) is the most common cause of chronic kidney disease in children. In cases of RH, proteinuria is often induced by glomerular hypertrophy and hyperfiltration that is commonly associated with focal segmental glomerulosclerosis. This study reports the first case series of a possible association between RH and membranous nephropathy (MN). METHODS: Of the 168 children with RH who visited our department between 1999 and 2017, five with overt proteinuria (≥ 1 g/gCr) underwent renal biopsy. We retrospectively reviewed the medical charts and analyzed biopsy specimens using light microscopy (LM), immunofluorescence (IF), and electron microscopy. RESULTS: The five children (four boys and one girl) had a median age of 5.5 years at the time of renal biopsy. The median proteinuria was 4.23 g/gCr (range 1.46-14.25), median serum albumin, 2.9 g/dL (range 2.3-3.7), and median estimated glomerular filtration rate, 59.7 mL/min/1.73 m2 (range 36.7-103.6). LM showed segmental spike formation and mesangial hypercellularity and IF study showed segmental granular immunoglobulin G (IgG) staining (IgG1 and IgG3 dominant) along the capillary loops in all five patients. Electron-dense deposits were observed in the subepithelial and mesangial areas. Thus, the pathological studies showed MN-like lesions in all patients. CONCLUSION: Our study suggests that RH can be the cause of MN-like lesions.

Individualized concept for the treatment of autosomal recessive polycystic kidney disease with end-stage renal disease.

Management of children with autosomal recessive polycystic kidney disease (ARPKD) who develop end-stage renal disease (ESRD) remains challenging because of concomitant liver disease. Patients with recurrent cholangitis are candidates for liver-kidney transplantation, while the treatment for patients with splenomegaly and pancytopenia due to portal hypertension is controversial. Herein, we report 7 children who were treated using an individualized treatment strategy stratified by liver disease. Two patients with recurrent cholangitis underwent sequential liver-kidney transplantation, while 4 patients with splenomegaly and pancytopenia but without recurrent cholangitis underwent splenectomy followed by isolated kidney transplantation. The remaining patient, who did not have cholangitis and pancytopenia, underwent isolated kidney transplantation. Blood cell counts were normalized after splenectomy was performed at the median age of 8.7 (range, 7.4-11.7) years. Kidney transplantation was performed at the median age of 8.8 (range, 1.9-14.7) years in all patients. Overwhelming post-splenectomy infections and cholangitis did not occur during the median follow-up period of 6.3 (range, 1.0-13.2) years. The estimated glomerular filtration rate at the last follow-up was 53 (range, 35-107) mL/min/1.73 m2 . No graft loss occurred. Our individualized treatment strategy stratified by recurrent cholangitis and pancytopenia can be a feasible strategy for children with ARPKD who develop ESRD and warrants further evaluation.

Long-term outcome of renal transplantation in childhood-onset anti-neutrophil cytoplasmic antibody-associated vasculitis.

BACKGROUND: There have been a few reports of RTx for AAV in children; however, post-transplant recurrence rate and long-term prognosis remain unclear. Here, we describe the long-term outcomes of RTx in childhood-onset AAV. METHODS: We conducted a retrospective study of children who underwent RTx for AAV between 1999 and 2017 and had a follow-up period of >2 years. RESULTS: Seven patients consisting of three children with MPA and four with RLV were analyzed. Age at Dx was 5.9 (median; range, 4.1-14.5) years. PD was instituted in all patients, and median time on dialysis was 26 (range, 14-63) months. Age at RTx was 12.8 (median; range, 8.7-16.3) years. There were no recurrences of AAV noted during the median follow-up period of 7.0 (range, 2.7-18.8) years after RTx. Graft loss occurred in one patient due to non-adherence. Estimated glomerular filtration rate of the remaining patients at the last follow-up was 73.0 (median; range, 50.7-93.9) mL/min/1.73 m2 . No malignancies and deaths occurred during the observational period. CONCLUSIONS: Our study suggests that RTx for AAV with ESRD is a potentially safe and effective treatment choice for children with AAV.

Clinical characteristics of Campylobacter enteritis after pediatric renal transplantation: A retrospective analysis from single center.

BACKGROUND: There are few reports of patients with Campylobacter enteritis after renal transplantation, and only a few case reports of bacteremia have been published. Although antibiotic therapy for 3-5 days has been recommended for immunocompromised patients, the optimal treatment for Campylobacter enteritis after renal transplantation has not been established. This study aimed to clarify the clinical characteristics and treatment outcomes of Campylobacter enteritis after pediatric renal transplantation. METHODS: This retrospective study included patients who underwent pediatric renal transplantation and were found to have Campylobacter species in stool cultures between January 2014 and May 2017. RESULTS: This study included eight patients who underwent pediatric renal transplantation. The median age at the time of renal transplantation was 14 years, and the median period between transplantation and disease occurrence was 4.6 years. Clinical symptoms were abdominal pain for eight patients, diarrhea for eight patients, fever for seven patients, vomiting for three patients, and headache for three patients. Campylobacter jejuni was isolated from the stool cultures of all patients. The median administration period of antibiotics as initial therapy was 7 days (range, 4-11 days). However, clinical relapse was observed in four patients after completing antibiotic therapy. Patients who experienced clinical relapse required a second course of antibiotic therapy for a median duration of 7 days (range, 5-10 days). CONCLUSIONS: Patients with Campylobacter enteritis after pediatric renal transplantation are at high risk for clinical relapse and may require a longer duration of antibiotic therapy than that generally described.

New-onset diabetes after renal transplantation in a patient with a novel HNF1B mutation.

CAKUT are the most frequent causes of ESRD in children. Mutations in the gene encoding HNF1B, a transcription factor involved in organ development and maintenance, cause a multisystem disorder that includes CAKUT, diabetes, and liver dysfunction. Here, we describe the case of a patient with renal hypodysplasia who developed NODAT presenting with liver dysfunction. The NODAT was initially thought to be steroid and FK related. However, based on the patient's clinical features, including renal hypodysplasia and recurrent elevations of transaminase, screening for an HNF1B mutation was performed. Direct sequencing identified a novel splicing mutation of HNF1B, designated c.344 + 2T>C. Because CAKUT is the leading cause of ESRD in children and HNF1B mutations can cause both renal hypodysplasia and diabetes, HNF1B mutations may account for a portion of the cases of NODAT in pediatric patients who have undergone kidney transplantation. NODAT is a serious and major complication of solid organ transplantation and is associated with reduced graft survival. Therefore, for the appropriate management of kidney transplantation, screening for HNF1B mutations should be considered in pediatric patients with transplants caused by CAKUT who develop NODAT and show extra-renal symptoms.