A multi-institutional study found a possible role of anti-nephrin antibodies in post-transplant focal segmental glomerulosclerosis recurrence.

Possible roles of anti-nephrin antibodies in post-transplant recurrent focal segmental glomerulosclerosis (FSGS) have been reported recently. To confirm these preliminary results, we performed a multi-institutional study of 22 Japanese pediatric kidney transplant recipients with FSGS including eight genetic FSGS and 14 non-genetic (presumed primary) FSGS. Eleven of the 14 non-genetic FSGS patients had post-transplant recurrent FSGS. Median (interquartile range) plasma levels of anti-nephrin antibodies in post-transplant recurrent FSGS measured using ELISA were markedly high at 899 (831, 1292) U/mL (cutoff 231 U/mL) before transplantation or during recurrence. Graft biopsies during recurrence showed punctate IgG deposition co-localized with nephrin that had altered localization with increased nephrin tyrosine phosphorylation and Src homology and collagen homology A expressions. Graft biopsies after remission showed no signals for IgG and a normal expression pattern of nephrin. Anti-nephrin antibody levels decreased to 155 (53, 367) U/mL in five patients with samples available after remission. In patients with genetic FSGS as in those with non-genetic FSGS without recurrence, anti-nephrin antibody levels were comparable to those of 30 control individuals, and graft biopsies had no signals for IgG and a normal expression pattern of nephrin. Thus, our results suggest that circulating anti-nephrin antibodies are a possible candidate for circulating factors involved in the pathogenesis of post-transplant recurrent FSGS and that this may be mediated by nephrin phosphorylation. Larger studies including other ethnicities are required to confirm this finding.

Clinical Course of Nonresponders With Recurrent Focal Segmental Glomerulosclerosis After Pediatric Kidney Transplantation: A Retrospective Multicenter Study.

BACKGROUND: Primary focal segmental glomerulosclerosis (FSGS) frequently recurs after kidney transplantation and is associated with poor graft survival. Patients who do not achieve remission (nonresponders) have an especially poor graft survival. However, the characteristics that may affect graft survival in nonresponders are unknown. This study aimed to determine the clinical characteristics associated with graft survival in nonresponders. METHODS: We retrospectively collected the clinical records of patients with FSGS and an age at onset <16 years who experienced posttransplant recurrence of FSGS at six hospitals in Japan from 1993 to 2018. RESULTS: Eight nonresponders with recurrent FSGS were enrolled in this study. The median time to recurrence after kidney transplantation was 1 day (interquartile range, 1-2 days). All patients received therapeutic plasma exchange and methylprednisolone pulse therapy. Rituximab was used as an add-on therapy in three patients. Five patients lost their graft within 2 years after kidney transplantation (rapid group). In contrast, three patients had much longer graft survival (nonrapid group). We compared the clinical characteristics of the rapid and nonrapid groups. Proteinuria tended to be lower in the nonrapid group at the third and subsequent months of therapy. The rapid group had persistent nephrotic syndrome. The rate of reduction in proteinuria was lower in the rapid group than in the nonrapid group. CONCLUSIONS: Our study suggests that persistent nephrotic syndrome and a low rate of reduction in proteinuria may predict rapid progression to graft failure in nonresponders.

A nationwide survey of MYH9-related disease in Japan.

BACKGROUND: MYH9-related disease (MYH9-RD) is characterized by congenital macrothrombocytopenia, Döhle body-like granulocyte inclusions, and nephropathy, which may progress to end-stage kidney disease (ESKD). However, information on the effects of renin-angiotensin system (RAS) inhibitors on kidney survival is currently lacking and the outcomes of kidney replacement therapy (KRT) in MYH9-RD are largely unknown. METHODS: We conducted a cross-sectional nationwide survey by sending questionnaires to 145 institutions in Japan and analyzed data for 49 patients. RESULTS: The median patient age was 27 years. Genetic analysis was performed in 37 (76%) patients. Twenty-four patients (65%) had MYH9 variants affecting the motor domain of non-muscle myosin heavy chain-IIA, and these patients had poorer kidney survival than those with variants affecting the tail domain (P = 0.02). There was no significant difference in kidney survival between patients treated with and without RAS inhibitors. Hemodialysis and peritoneal dialysis were performed in 16 and 7 patients, respectively. There were no major bleeding complications during the perioperative period or during follow-up, except for one patient. Most of the 11 patients who underwent kidney transplantation required perioperative red cell concentrate transfusions, but there was no graft loss during the median posttransplant observational period of 2.0 (interquartile range, 1.3-6.8) years. CONCLUSION: Our study demonstrated no beneficial effect of RAS inhibitors on kidney function in patients with MYH9-RD, indicating the need for further studies with more patients. All modalities of KRT are feasible options for MYH9-RD patients who progress to ESKD, with adequate attention to bleeding complications.

Survival analysis among pediatric patients receiving kidney replacement therapy: a Japanese nationwide cohort study.

BACKGROUND: Limited data are available on the survival and causes of death in pediatric patients with chronic kidney disease (CKD) stage 5 receiving kidney replacement therapy (KRT) in Asia. METHODS: Data were obtained from the Japanese nationwide cross-sectional CKD stage 5 survey on pediatric patients (<20 years of age) who started KRT from 2006 to 2013. The cohort was divided into three groups according to age at the start of KRT: <1, 1-5, and 6-19 years. RESULTS: Among the 701 children who were included, 59.3% were boys. Peritoneal dialysis was the most common initial modality of KRT (60.3%). Median age at KRT initiation was 10.2 years. Infants (<1 year old) accounted for 16.0% of the total cohort. Overall survival at 1 and 5 years was 97.2% and 92.5%, respectively. Infants had significantly lower survival rates than the other groups (hazard ratio, 5.35; 95% CI, 2.60-11.03; P < 0.001). In contrast, after the age of 1 year, the survival rate improved and did not differ from that of other age groups. The most common causes of death were infection (35.9%) and sudden death (15.4%). CONCLUSIONS: The overall survival rate of pediatric patients with CKD stage 5 in Japan is like that in other high-income countries. Age at initiation of KRT is an important factor affecting survival since the poorest survival rate was observed in infants. Further improvement in infant dialysis therapy is still needed to improve survival of the youngest children. A higher resolution version of the Graphical abstract is available as Supplementary information.

Precise clinicopathologic findings for application of genetic testing in pediatric kidney transplant recipients with focal segmental glomerulosclerosis/steroid-resistant nephrotic syndrome.

BACKGROUND: Establishing a molecular genetic diagnosis of focal segmental glomerulosclerosis (FSGS)/steroid-resistant nephrotic syndrome (SRNS) can be useful for predicting post-transplant recurrence. Monogenic causes are reportedly present in approximately 20-30% of patients with FSGS/SRNS. However, the characteristics of patients who are likely to have a monogenic cause remain to be determined. METHODS: Pediatric recipients with SRNS and/or biopsy-proven FSGS who underwent their first kidney transplantation at our center between 1999 and 2019 were analyzed. Patients with secondary FSGS/SRNS were excluded. The recipients were divided into three groups: familial/syndromic, presumed primary, and undetermined FSGS/SRNS. Patients who met all of the following criteria were categorized as having presumed primary FSGS/SRNS: (i) nephrotic syndrome, (ii) complete or partial remission with initial steroid therapy and/or additional immunosuppressive therapies, and (iii) diffuse foot process effacement on electron microscopy in the native kidney biopsy. All patients underwent genetic testing using next-generation sequencing. RESULTS: Twenty-four patients from 23 families were analyzed in this study. Pathogenic or likely pathogenic variants in FSGS/SRNS-related genes were identified in four of four families, zero of eight families, and 10 of 11 families with familial/syndromic, presumed primary, and undetermined FSGS/SRNS, respectively. Post-transplant recurrence only occurred in patients with presumed primary FSGS/SRNS. CONCLUSIONS: Our systematic approach based on precise clinicopathological findings including nephrotic syndrome, treatment responses, and diffuse foot process effacement might be useful to differentiate pediatric kidney transplant recipients with FSGS/SRNS who are likely to have a monogenic cause from patients who are not, and to predict post-transplant recurrence. A higher resolution version of the Graphical abstract is available as Supplementary information.

Pioglitazone enhances proteinuria reduction in complicated pediatric nephrotic syndrome.

BACKGROUND: Nephrotic syndrome (NS) is a common pediatric kidney disease, yet current treatments for complicated NS are only partially effective and have significant toxicity. There is no Food and Drug Administration (FDA)- or European Medicines Agency (EMA)-approved safe and effective treatment for NS. Thiazolidinediones (TZDs) have been shown to reduce proteinuria in both diabetic and non-diabetic kidney disease and in preclinical studies to directly protect podocytes from injury and reduce proteinuria. Here, we report on the potential utility of the addition of the TZD pioglitazone (PIO) to enhance proteinuria reduction in 8 children and young adults with steroid dependent NS and steroid resistant NS. METHODS: Clinical data were analyzed in comparable time periods before and after the addition of PIO to their medical regimens. Eight NS patients with minimal change NS (n = 2), focal segmental glomerulosclerosis (FSGS) (n = 4), or collapsing FSGS (n = 2) were evaluated. RESULTS: Prior to PIO initiation, all children and young adults had already received multiple immunosuppressive medications (mean = 3.75). Five of eight patients (63%; "Responders") had notable proteinuria reduction within 1 month of PIO initiation (62% reduction; P = 0.04) and normalization within 6 months (97% reduction; P = 0.04). PIO-related benefits among the responders included notable increases in serum albumin (2.5 to 3.7 g/dl; P = 0.08), dramatic reductions in hospitalizations for IV albumin infusions and diuresis (11 to 0; P < 0.01), and considerable reduction in total immunosuppression (43% reduction; P > 0.1). Importantly, no patients experienced any adverse events attributable to PIO during a total of 136 patient-months of treatment. CONCLUSIONS: While confirmatory safety and efficacy studies are needed, these findings suggest pioglitazone (a non-immunosuppressive drug) may be useful to enhance proteinuria reduction in some children and young adults with complicated NS. A higher resolution version of the Graphical abstract is available as Supplementary information.

Medical and psychosocial outcomes in adolescents and young adults with childhood-onset end-stage kidney disease: a multicenter study in Japan.

BACKGROUND: Adolescents and young adults face various socio-emotional and behavioral challenges that can affect their medical and psychosocial outcomes. Pediatric patients with end-stage kidney disease (ESKD) often have extra-renal manifestations, including intellectual disability. However, limited data are available regarding the impact of extra-renal manifestations on medical and psychosocial outcomes among adolescents and young adults with childhood-onset ESKD. METHODS: Patients born between January 1982 and December 2006 that had developed ESKD in 2000 and later at age < 20 years were enrolled in this multicenter study in Japan. Data for patients' medical and psychosocial outcomes were retrospectively collected. Associations between extra-renal manifestations and these outcomes were analyzed. RESULTS: In total, 196 patients were analyzed. The mean age at ESKD was 10.8 years, and at last follow-up was 23.5 years. The first modality of kidney replacement therapy was kidney transplantation, peritoneal dialysis, and hemodialysis in 42, 55 and 3% of patients, respectively. Extra-renal manifestations were documented in 63% of patients and 27% had intellectual disability. Baseline height at kidney transplantation and intellectual disability significantly impacted final height. Six (3.1%) patients died, of which five (83%) had extra-renal manifestations. Patients' employment rate was lower than that in the general population, especially among those with extra-renal manifestations. Patients with intellectual disability were less likely to be transferred to adult care. CONCLUSIONS: Extra-renal manifestations and intellectual disability in adolescents and young adults with ESKD had considerable impacts on linear growth, mortality, employment, and transfer to adult care.

Depression and health-related quality of life in adolescents and young adults with childhood-onset end-stage kidney disease: a multicenter study in Japan.

BACKGROUND: Patient survival and physical outcomes among children with end-stage kidney disease (ESKD) have significantly improved, and recent research has focused on long-term depression symptoms and health-related quality of life (HRQOL). However, no studies have been conducted among adolescents and young adults with childhood-onset ESKD in Japan. METHODS: This multicenter study included 45 adolescents and young adults aged 16-39 years who developed ESKD at age < 20 years. Depression symptoms were measured using the Beck Depression Inventory (BDI)-II. The Short Form-36 Health Survey (SF-36) was used to assess HRQOL. Factors associated with depression and HRQOL were analyzed. RESULTS: Depression (BDI-II score ≥ 14) was observed in 13 (29%) patients. Patient's SF-36 physical component summary (PCS) and mental component summary (MCS) scores were comparable with those for the general population. Lower estimated glomerular filtration rate, higher BDI-II scores, and lower body mass index were associated with lower PCS scores. BDI-II scores were negatively correlated with MCS scores. We observed a trend that unemployment was associated with lower MCS scores. CONCLUSIONS: Depression is frequently observed among adolescents and young adults with childhood-onset ESKD. Regular screening for psychosocial concerns, maintaining stable graft functions, and achieving optimal nutritional status may contribute to improved well-being among these patients.

Response to steroid and immunosuppressive therapies may predict post-transplant recurrence of steroid-resistant nephrotic syndrome.

BACKGROUND: Recurrence of SRNS is a major challenge in KT. Several clinical factors, including initial steroid sensitivity, have been associated with increased post-transplant SRNS recurrence risk. However, conflicting data have been reported, possibly due to the heterogeneous pathophysiology of SRNS and the lack of genetic testing of SRNS patients. Furthermore, the response to immunosuppressive therapies has not been evaluated. METHODS: Seventy patients aged 1-15 years at SRNS onset who underwent KT between 2002 and 2018 were enrolled. Patients with secondary, familial, syndromic, and genetic forms of SRNS and those who were not treated with steroid were excluded. This study aimed to assess the risk factors for post-transplant recurrence, including treatment responses to initial steroid therapy and additional therapies with immunosuppressive agents, rituximab, plasmapheresis, and/or LDL-A. RESULTS: Data from 36 kidney transplant recipients were analyzed. Twenty-two (61%) patients experienced post-transplant SRNS recurrence, while 14 patients did not. The proportion of patients who achieved complete or partial remission with initial steroid therapy and/or additional therapies with immunosuppressive agents, rituximab, plasmapheresis, and/or LDL-A was significantly higher in the SRNS recurrence group (19/22, 86%) than in the group without SRNS recurrence (6/14, 43%; p = .01). CONCLUSION: This study suggests that the response to steroid treatment, other immunosuppressive agents, rituximab, plasmapheresis, and/or LDL-A may predict post-transplant SRNS recurrence.

Acute kidney injury due to ammonium acid urate stones in a patient with adenovirus gastroenteritis: a case report.

BACKGROUND: Adenovirus gastroenteritis is a common cause of diarrhea and vomiting in infants, resulting in prerenal acute kidney injury (AKI). However, postrenal AKI due to urinary stones associated with adenovirus gastroenteritis is extremely rare. Here, we describe postrenal AKI due to obstructive ammonium acid urate stones associated with adenovirus gastroenteritis. CASE PRESENTATION: A previously healthy 6-month-old boy had an 11-day history of severe diarrhea and a 5-day history of vomiting. His stool was positive for adenovirus antigens. We initiated fluid replacement therapy. On the second hospital day, he suddenly developed anuria. Abdominal computed tomography revealed bilateral hydronephrosis, left ureteral stones, and right bladder ureteral junction stones. Laboratory data showed that the creatinine level increased to 1.00 mg/dL. We diagnosed postrenal AKI due to obstructive bilateral urinary stones. Urination with stable urine volume resumed spontaneously after hydration. A few stones were found in the urine, which consisted of ammonium acid urate (> 98%). The serum creatinine level improved to 0.25 mg/dL. He was discharged nine days after admission. CONCLUSIONS: We suggest that adenovirus gastroenteritis be considered in pediatric patients with postrenal AKI due to urinary stones.

Serum sodium level is inversely correlated with body temperature in children.

BACKGROUND: Several studies have demonstrated that non-osmotic antidiuretic hormone activity contributes to the development of hyponatremia in children with common febrile diseases. However, the relationship between hyponatremia and body temperature has remained unclear. We therefore examined this relationship in children with common diseases. METHODS: In this retrospective case study based on a chart review, 1,973 children presenting with acute illnesses at Hirakata City Hospital between November 2008 and October 2009, and for whom blood test data were available, were enrolled. The median age of this cohort was 2.7 years and the mean serum sodium concentration was 136.4 mEq/L; 454 patients showed hyponatremia (<135 mEq/L). The patients were classified into four groups on the basis of body temperature, <37 °C, 37 °C (37.0-37.9 °C), 38 °C (38.0-38.9 °C) and ≥39 °C, and their serum sodium concentration was compared. RESULTS: The mean sodium level was significantly lower in febrile (135.9 mEq/L) than in non-febrile (138.5 mEq/L) patients. The mean serum sodium levels in the four temperature groups were, in ascending order, 138.5 mEq/L (95% CI, 138.3-138.8 mEq/L), 137.3 mEq/L (137.1-137.5 mEq/L), 136.1 mEq/L (135.8-136.3 mEq/L) and 134.6 mEq/L (134.4-134.9 mEq/L), respectively. The serum sodium level in each individual temperature range became significantly lower as body temperature increased (P < 0.001). CONCLUSIONS: There is a clear inverse correlation between serum sodium level and body temperature in children with common febrile diseases, and fever may play an important role in this relationship.

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.

Monoclonal and polyclonal immunoglobulin G deposits on tubular basement membranes of native and pretransplant kidneys: A retrospective study.

Monoclonal tubular basement membrane immune deposits (TBMID) are associated with progression of interstitial injury in renal allograft. However, the significance of monoclonal and polyclonal TBMID in the native kidney remains unclear. We retrospectively analyzed 1894 native kidney biopsies and 1724 zero-hour biopsies performed between 2008 and 2018 in our institution. The rate of immunoglobulin G (IgG) TBMID was found to be 8.4% among native kidney biopsies and 0.4% among zero-hour biopsies. Polyclonal TBMID is common in IgG4-related tubulointerstitial nephritis (37.5%), diabetic nephropathy (31.3%) and lupus nephritis (25.5%). Monoclonal IgG TBMID was identified in seven cases, including three zero-hour biopsies. The combination of IgG1κ was observed in two cases, IgG1λ in three, and IgG2κ in two. Electron microscopy revealed powdery electron-dense deposits in all cases. Monoclonal gammopathy of undetermined significance was diagnosed in one case. Although one patient with focal segmental glomerulosclerosis developed renal failure, all others exhibited stable renal function. Monoclonal IgG TBMID in the native kidney is not associated with renal prognosis. However, this may be an interesting immunopathological finding that would help clarify the pathogenesis of TBM immune deposits. Further study for both monoclonal and polyclonal TBMID is required in the future.

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.

Clinical and histological features in pediatric and adolescent/young adult patients with renal disease: a cross-sectional analysis of the Japan Renal Biopsy Registry (J-RBR).

BACKGROUND: Only a few studies have investigated epidemiological and clinicopathological information regarding pediatric and adolescent and young adult (AYA) patients with renal disease. The purpose of this study was to clarify the differences and relationship of clinicopathological findings between pediatric and AYA patients using the Japan Renal Biopsy Registry (J-RBR). METHODS: This cross-sectional study analyzed data from patients registered in the J-RBR between 2007 and 2017. Clinicopathological findings at diagnosis were analyzed for 3,463 pediatric (age < 15 years) and 6,532 AYA (age 15-30 years) patients. RESULTS: Although chronic nephritic syndrome was the most common clinical diagnosis at age > 5 years, nephrotic syndrome was the most frequent diagnosis at age < 4 years. The most common pathological diagnosis as classified by pathogenesis in pediatric patients was primary glomerular disease (except IgA nephropathy), whereas IgA nephropathy was increased in AYA patients. Mesangial proliferative glomerulonephritis was the most common pathological diagnosis as classified by histopathology in both pediatric and AYA patients. Minor glomerular abnormalities were the most frequent histopathologic diagnoses of nephrotic syndrome in childhood, but their frequency decreased with age. CONCLUSION: To the best of our knowledge, this is the first report of clinicopathological features of pediatric and AYA patients in a large nationwide registry of renal biopsy. There were differences of clinical, pathological and histopathologic findings between pediatric and AYA patients.

A novel de novo truncating TRIM8 variant associated with childhood-onset focal segmental glomerulosclerosis without epileptic encephalopathy: a case report.

BACKGROUND: Heterozygous truncating variants in the Tripartite motif containing 8 (TRIM8) gene have been reported to cause epileptic encephalopathy, both with and without proteinuria. A recent study showed a lack of TRIM8 protein expression, with suppressor of cytokine signaling 1 (SOCS1) overexpression, in podocytes and tubules from a patient with a TRIM8 variant, who presented with epileptic encephalopathy and focal segmental glomerulosclerosis (FSGS). To date, no patients with TRIM8 variants who presented with nephrotic syndrome but without neurological manifestations have been described. CASE PRESENTATION: An 8-year-old girl presented with nephrotic syndrome, without epilepsy or developmental delay. Her kidney biopsy specimens showed FSGS and cystic dilatations of the distal tubules. Whole-exome sequencing identified a novel de novo heterozygous variant in the C-terminal encoding portion of TRIM8 (c.1461C > A), resulting in a premature stop codon (p.Tyr487*). Reverse transcription-polymerase chain reaction using peripheral blood mononuclear cells identified the mRNA sequence of the mutant allele, which confirmed an escape from nonsense-mediated mRNA decay. Immunofluorescence studies showed a lack of TRIM8 expression in glomerular and tubular cells and cystic dilatation of distal tubules. Immunohistochemical studies showed overexpression of SOCS1 in glomerular and tubular cells. CONCLUSIONS: We reported a patient with FSGS, associated with a de novo heterozygous TRIM8 variant, without any neurological manifestations. Our results expanded the clinical phenotypic spectrum of TRIM8 variants.

Deletion in the Cobalamin Synthetase W Domain-Containing Protein 1 Gene Is associated with Congenital Anomalies of the Kidney and Urinary Tract.

BACKGROUND: Researchers have identified about 40 genes with mutations that result in the most common cause of CKD in children, congenital anomalies of the kidney and urinary tract (CAKUT), but approximately 85% of patients with CAKUT lack mutations in these genes. The anomalies that comprise CAKUT are clinically heterogenous, and thought to be caused by disturbances at different points in kidney development. However, identification of novel CAKUT-causing genes remains difficult because of their variable expressivity, incomplete penetrance, and heterogeneity. METHODS: We investigated two generations of a family that included two siblings with CAKUT. Although the parents and another child were healthy, the two affected siblings presented the same manifestations, unilateral renal agenesis and contralateral renal hypoplasia. To search for a novel causative gene of CAKUT, we performed whole-exome and whole-genome sequencing of DNA from the family members. We also generated two lines of genetically modified mice with a gene deletion present only in the affected siblings, and performed immunohistochemical and phenotypic analyses of these mice. RESULTS: We found that the affected siblings, but not healthy family members, had a homozygous deletion in the Cobalamin Synthetase W Domain-Containing Protein 1 (CBWD1) gene. Whole-genome sequencing uncovered genomic breakpoints, which involved exon 1 of CBWD1, harboring the initiating codon. Immunohistochemical analysis revealed high expression of Cbwd1 in the nuclei of the ureteric bud cells in the developing kidneys. Cbwd1-deficient mice showed CAKUT phenotypes, including hydronephrosis, hydroureters, and duplicated ureters. CONCLUSIONS: The identification of a deletion in CBWD1 gene in two siblings with CAKUT implies a role for CBWD1 in the etiology of some cases of CAKUT.

Kidney function of Japanese children undergoing kidney transplant with preemptive therapy for cytomegalovirus infection.

BACKGROUND: Cytomegalovirus (CMV) infection is one of the major factors that affect morbidity and mortality in kidney transplant (KTx) patients. The rate of CMV seropositivity in children before KTx is lower than that in adults; therefore, pediatric KTx patients have a higher risk of CMV infection. In Japanese pediatric KTx patients, preemptive therapy for CMV infection is a main conventional therapy. This study investigated whether this preemptive treatment would affect kidney function at 2 years post-KTx. METHODS: A total of 163 patients, that is approximately half of the Japanese pediatric KTx patients nationwide, were recruited to participate in our study. We compared the values of the sequential estimated glomerular filtration rate (eGFR) at two years post-KTx and other influencing factors in CMV viremia, CMV disease, and no-infection groups. RESULTS: Cytomegalovirus infection after KTx occurred in 75 patients (46.0%), 38.7% of whom developed CMV disease. The sequential eGFR values post-KTx did not differ significantly between the three groups. CMV infection was not significantly correlated with other factors, other infections (including Epstein-Barr [EB] virus infection), acute rejection (AR), or adverse events. Only prolonged duration of total hospitalization was significantly associated with CMV infection (P = .002). In the multivariate analysis, younger age, CMV infection, and adverse effects were independently significantly related to prolonged total hospitalization. CONCLUSION: Preemptive therapy for CMV infection evidenced by viremia and disease did not significantly influence kidney function in Japanese pediatric KTx patients at two years after the operation.

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.

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.