SSBP1 mutations cause mtDNA depletion underlying a complex optic atrophy disorder.

Inherited optic neuropathies include complex phenotypes, mostly driven by mitochondrial dysfunction. We report an optic atrophy spectrum disorder, including retinal macular dystrophy and kidney insufficiency leading to transplantation, associated with mitochondrial DNA (mtDNA) depletion without accumulation of multiple deletions. By whole-exome sequencing, we identified mutations affecting the mitochondrial single-strand binding protein (SSBP1) in 4 families with dominant and 1 with recessive inheritance. We show that SSBP1 mutations in patient-derived fibroblasts variably affect the amount of SSBP1 protein and alter multimer formation, but not the binding to ssDNA. SSBP1 mutations impaired mtDNA, nucleoids, and 7S-DNA amounts as well as mtDNA replication, affecting replisome machinery. The variable mtDNA depletion in cells was reflected in severity of mitochondrial dysfunction, including respiratory efficiency, OXPHOS subunits, and complex amount and assembly. mtDNA depletion and cytochrome c oxidase-negative cells were found ex vivo in biopsies of affected tissues, such as kidney and skeletal muscle. Reduced efficiency of mtDNA replication was also reproduced in vitro, confirming the pathogenic mechanism. Furthermore, ssbp1 suppression in zebrafish induced signs of nephropathy and reduced optic nerve size, the latter phenotype complemented by WT mRNA but not by SSBP1 mutant transcripts. This previously unrecognized disease of mtDNA maintenance implicates SSBP1 mutations as a cause of human pathology.

Tailored use of belatacept in adolescent kidney transplantation.

Adolescent transplant recipients are at risk for nonadherence, development of de novo donor-specific antibody (dnDSA), and allograft loss. Belatacept, a selective T cell costimulatory blocker, is associated with reduced dnDSA, improved renal function, and prolonged allograft survival when compared to calcineurin inhibitor-based regimens in adults; however, its use in children is scant. Three adolescents were initiated on belatacept between August 2017 and September 2018 at the time of kidney transplantation. Selection criteria included age ≥ 14 and EBV IgG + serostatus. Intraoperative alemtuzumab and methylprednisolone were given as induction therapy. Tailored maintenance therapy included steroid-free belatacept and sirolimus for two patients. One patient was initially maintained steroid-free on belatacept and belimumab, an inhibitor of B cell activating factor to treat concurrent systemic lupus erythematous; steroids were added subsequently. Renal function, biopsy-proven rejection, dnDSA, allograft survival, infection, nonadherence, and proteinuria were monitored. Renal function was 86, 73, 52 mL/min/1.73 m2 at 20, 20, and 8 months, respectively. There was 100% adherence to therapy and no development of dnDSA. All patients had treatable infections. One developed steroid-responsive acute cellular rejection. Belatacept-based regimens can be tailored for adolescent recipients with good short-term clinical outcomes.

Psychosocial Assessment of Candidates for Transplantation (PACT) Score Identifies High Risk Patients in Pediatric Renal Transplantation.

Background: Currently, there is no standardized approach for determining psychosocial readiness in pediatric transplantation. We examined the utility of the Psychosocial Assessment of Candidates for Transplantation (PACT) to identify pediatric kidney transplant recipients at risk for adverse clinical outcomes. Methods: Kidney transplant patients <21-years-old transplanted at Duke University Medical Center between 2005 and 2015 underwent psychosocial assessment by a social worker with either PACT or unstructured interview, which were used to determine transplant candidacy. PACT assessed candidates on a scale of 0 (poor candidate) to 4 (excellent candidate) in areas of social support, psychological health, lifestyle factors, and understanding. Demographics and clinical outcomes were analyzed by presence or absence of PACT and further characterized by high (≥3) and low (≤2) scores. Results: Of 54 pediatric patients, 25 (46.3%) patients underwent pre-transplant evaluation utilizing PACT, while 29 (53.7%) were not evaluated with PACT. Patients assessed with PACT had a significantly lower percentage of acute rejection (16.0 vs. 55.2%, p = 0.007). After adjusting for HLA mismatch, a pre-transplant PACT score was persistently associated with lower odds of acute rejection (Odds Ratio 0.119, 95% Confidence Interval 0.027-0.52, p = 0.005). In PACT subsection analysis, the lack of family availability (OR 0.08, 95% CI 0.01-0.97, p = 0.047) and risk for psychopathology (OR 0.34, 95% CI 0.13-0.87, p = 0.025) were associated with a low PACT score and post-transplant non-adherence. Conclusions: Our study highlights the importance of standardized psychosocial assessments and the potential use of PACT in risk stratifying pre-transplant candidates.

Correction to: Recurrence of nephrotic syndrome following kidney transplantation is associated with initial native kidney biopsy findings : A Midwest Pediatric Nephrology Consortium (MWPNC) study.

The original version of this article unfortunately contained a mistake. The subtitle "A Midwest Pediatric Nephrology Consortium (MWPNC) study" was missing. The correct title including subtitle is given above.

Recurrence of nephrotic syndrome following kidney transplantation is associated with initial native kidney biopsy findings.

BACKGROUND AND OBJECTIVES: Steroid-resistant nephrotic syndrome (SRNS) due to focal segmental glomerulosclerosis (FSGS) and minimal change disease (MCD) is a leading cause of end-stage kidney disease in children. Recurrence of primary disease following transplantation is a major cause of allograft loss. The clinical determinants of disease recurrence are not completely known. Our objectives were to determine risk factors for recurrence of FSGS/MCD following kidney transplantation and factors that predict response to immunosuppression following recurrence. METHODS: Multicenter study of pediatric patients with kidney transplants performed for ESKD due to SRNS between 1/2006 and 12/2015. Demographics, clinical course, and biopsy data were collected. Patients with primary-SRNS (PSRNS) were defined as those initially resistant to corticosteroid therapy at diagnosis, and patients with late-SRNS (LSRNS) as those initially responsive to steroids who subsequently developed steroid resistance. We performed logistic regression to determine risk factors associated with nephrotic syndrome (NS) recurrence. RESULTS: We analyzed 158 patients; 64 (41%) had recurrence of NS in their renal allograft. Disease recurrence occurred in 78% of patients with LSRNS compared to 39% of those with PSRNS. Patients with MCD on initial native kidney biopsy had a 76% recurrence rate compared with a 40% recurrence rate in those with FSGS. Multivariable analysis showed that MCD histology (OR; 95% CI 5.6; 1.3-23.7) compared to FSGS predicted disease recurrence. CONCLUSIONS: Pediatric patients with MCD and LSRNS are at higher risk of disease recurrence following kidney transplantation. These findings may be useful for designing studies to test strategies for preventing recurrence.

Looking beyond the exome: a phenotype-first approach to molecular diagnostic resolution in rare and undiagnosed diseases.

PurposeTo describe examples of missed pathogenic variants on whole-exome sequencing (WES) and the importance of deep phenotyping for further diagnostic testing.MethodsGuided by phenotypic information, three children with negative WES underwent targeted single-gene testing.ResultsIndividual 1 had a clinical diagnosis consistent with infantile systemic hyalinosis, although WES and a next-generation sequencing (NGS)-based ANTXR2 test were negative. Sanger sequencing of ANTXR2 revealed a homozygous single base pair insertion, previously missed by the WES variant caller software. Individual 2 had neurodevelopmental regression and cerebellar atrophy, with no diagnosis on WES. New clinical findings prompted Sanger sequencing and copy number testing of PLA2G6. A novel homozygous deletion of the noncoding exon 1 (not included in the WES capture kit) was detected, with extension into the promoter, confirming the clinical suspicion of infantile neuroaxonal dystrophy. Individual 3 had progressive ataxia, spasticity, and magnetic resonance image changes of vanishing white matter leukoencephalopathy. An NGS leukodystrophy gene panel and WES showed a heterozygous pathogenic variant in EIF2B5; no deletions/duplications were detected. Sanger sequencing of EIF2B5 showed a frameshift indel, probably missed owing to failure of alignment.ConclusionThese cases illustrate potential pitfalls of WES/NGS testing and the importance of phenotype-guided molecular testing in yielding diagnoses.

Neutropenic enterocolitis (typhlitis) in a pediatric renal transplant patient. A case report and review of the literature.

NE (typhlitis) is a potentially life-threatening disease process characterized by bowel wall edema, ulceration, and hemorrhage in an immunosuppressed patient. We report a 15-year-old boy status post deceased donor renal transplantation who presented with fever, abdominal pain, and diarrhea. Laboratory studies revealed neutropenia 5 days prior to admission, and abdominal computed tomography revealed bowel wall thickening in the cecum consistent with NE. He was treated with piperacillin-tazobactam and gentamicin and recovered. To our knowledge, this is the first report of a case of NE in a pediatric kidney transplant recipient.

Rare variants in tenascin genes in a cohort of children with primary vesicoureteric reflux.

BACKGROUND: Primary vesicoureteral reflux (PVUR) is the most common malformation of the kidney and urinary tract, and reflux nephropathy is a major cause of chronic kidney disease in children. Recently, we reported mutations in the tenascin XB gene (TNXB) as a cause of PVUR with joint hypermobility. METHODS: To define the role of rare variants in tenascin genes in the etiology of PVUR, we screened a cohort of patients with familial PVUR (FPVUR) and non-familial PVUR (NFPVUR) for rare missense variants inTNXB and the tenascin C gene (TNC) after excluding mutations in ROBO2 and SOX17. RESULTS: The screening procedure identified 134 individuals from 112 families with PVUR; two families with mutations in ROBO2 were excluded from further analysis. Rare missense variants in TNXB were found in the remaining 110 families, of which 5/55 (9%) families had FPVUR and 2/55 (4%) had NFPVUR. There were no differences in high-grade reflux or renal parenchymal scarring between patients with and without TNXB variants. All patients with TNXB rare variants who were tested exhibited joint hypermobility. Overall we were able to identify causes of FPVUR in 7/57 (12%) families (9% in TNXB and 3% in ROBO2). CONCLUSIONS: In conclusion, the identification of a rare missense variant in TNXB in combination with a positive family history of VUR and joint hypermobility may represent a non-invasive method to diagnose PVUR and warrants further evaluation in other cohorts.

Variability in phenotype induced by the podocin variant R229Q plus a single pathogenic mutation.

BACKGROUND: Mutations in podocin (NPHS2) are the most common cause of childhood onset autosomal recessive steroid-resistant nephrotic syndrome (SRNS). The disease is characterized by early-onset proteinuria, resistance to immunosuppressive therapy and rapid progression to end-stage renal disease. Compound heterozygous changes involving the podocin variant R229Q combined with another pathogenic mutation have been associated with a mild phenotype with disease onset often in adulthood. METHODS: We screened 19 families with early-onset SRNS for mutations in NPHS2 and WT1 and identified four disease-causing mutations (three in NPHS2 and one in WT1) prior to planned whole-exome sequencing. RESULTS: We describe two families with three individuals presenting in childhood who are compound heterozygous for R229Q and one other pathogenic NPHS2 mutation, either L327F or A297V. One child presented at age 4 years (A297V plus R229Q) and the other two at age 13 (L327F plus R229Q), one with steadily deteriorating renal function. CONCLUSIONS: These cases highlight the phenotypic variability associated with the NPHS2 R229Q variant plus pathogenic mutation. Individuals may present with early aggressive disease.

Efficacy of antibiotic prophylaxis in children with vesicoureteral reflux: systematic review and meta-analysis.

PURPOSE: Controversy exists regarding the use of continuous antibiotic prophylaxis vs observation in the management of children with vesicoureteral reflux. The reported effectiveness of continuous antibiotic prophylaxis in children with reflux varies widely. We determined whether the aggregated evidence supports use of continuous antibiotic prophylaxis in children with vesicoureteral reflux. MATERIALS AND METHODS: We searched the Cochrane Controlled Trials Register, clinicaltrials.gov, MEDLINE(®), EMBASE(®), Google Scholar and recently presented meeting abstracts for reports in any language. Bibliographies of included studies were then hand searched for any missed articles. The study protocol was prospectively registered at PROSPERO (No. CRD42014009639). Reports were assessed and data abstracted in duplicate, with differences resolved by consensus. Risk of bias was assessed using standardized instruments. RESULTS: We identified 1,547 studies, of which 8 are included in the meta-analysis. Pooled results demonstrated that continuous antibiotic prophylaxis significantly reduced the risk of recurrent febrile or symptomatic urinary tract infection (pooled OR 0.63, 95% CI 0.42-0.96) but, if urinary tract infection occurred, increased the risk of antibiotic resistant organism (pooled OR 8.75, 95% CI 3.52-21.73). A decrease in new renal scarring was not associated with continuous antibiotic prophylaxis use. Adverse events were similar between the 2 groups. Significant heterogeneity existed between studies (I(2) 50%, p = 0.03), specifically between those trials with significant risk of bias (eg unclear protocol descriptions and/or lack of blinding). CONCLUSIONS: Compared to no treatment, continuous antibiotic prophylaxis significantly reduced the risk of febrile and symptomatic urinary tract infections in children with vesicoureteral reflux, although it increased the risk of infection due to antibiotic resistant bacteria. Continuous antibiotic prophylaxis did not significantly impact the occurrence of new renal scarring or reported adverse events.

HLA-DQA1 and PLCG2 Are Candidate Risk Loci for Childhood-Onset Steroid-Sensitive Nephrotic Syndrome.

Steroid-sensitive nephrotic syndrome (SSNS) accounts for >80% of cases of nephrotic syndrome in childhood. However, the etiology and pathogenesis of SSNS remain obscure. Hypothesizing that coding variation may underlie SSNS risk, we conducted an exome array association study of SSNS. We enrolled a discovery set of 363 persons (214 South Asian children with SSNS and 149 controls) and genotyped them using the Illumina HumanExome Beadchip. Four common single nucleotide polymorphisms (SNPs) in HLA-DQA1 and HLA-DQB1 (rs1129740, rs9273349, rs1071630, and rs1140343) were significantly associated with SSNS at or near the Bonferroni-adjusted P value for the number of single variants that were tested (odds ratio, 2.11; 95% confidence interval, 1.56 to 2.86; P=1.68×10(-6) (Fisher exact test). Two of these SNPs-the missense variants C34Y (rs1129740) and F41S (rs1071630) in HLA-DQA1-were replicated in an independent cohort of children of white European ancestry with SSNS (100 cases and ≤589 controls; P=1.42×10(-17)). In the rare variant gene set-based analysis, the best signal was found in PLCG2 (P=7.825×10(-5)). In conclusion, this exome array study identified HLA-DQA1 and PLCG2 missense coding variants as candidate loci for SSNS. The finding of a MHC class II locus underlying SSNS risk suggests a major role for immune response in the pathogenesis of SSNS.

Neurogenic bladder dysfunction presenting as urinary retention in neuronopathic Gaucher disease.

Neuronopathic Gaucher disease can present as a continuum of clinical findings, including somatic symptoms of anemia, thrombocytopenia, hepatosplenomegaly, and bone disease as well as neurologic sequelae. There is a spectrum of neurologic symptoms ranging from oculomotor apraxia to severe convulsions. The heterozygosity of phenotypes makes it difficult to predict the disease course. We describe an 8-year-old male with neuronopathic type III Gaucher disease who developed bladder dysfunction and was unable to completely void. He also presented with hypertension and acute renal insufficiency, most likely secondary to urinary retention. A complete evaluation was done for causes of urinary retention and bladder dysfunction. A renal bladder ultrasound demonstrated marked hydroureteronephrosis. There was no clinical evidence of infection and cystoscopy revealed no anatomic obstruction. In addition, MRI showed no spinal abnormalities. His bladder dysfunction was managed operatively by creating a catheterizable stoma, using his appendix, to empty his bladder, and surgical findings were consistent with neurogenic bladder. He continues to be managed for his Gaucher disease and neurogenic bladder by genetics, nephrology and urology. This is the first clinical report of neurogenic bladder dysfunction in neuronopathic Gaucher disease.

A de novo novel missense mutation in AVPR2 with severe nephrogenic diabetes insipidus.

We describe a paediatric case of nephrogenic diabetes insipidus (NDI) with a novel mutation in the arginine vasopressin receptor 2 gene (AVPR2) in the absence of a family history of congenital polyuria. The patient, a 5-month-old Caucasian boy, had failure to thrive and hypernatraemia. On admission to hospital, he had a plasma sodium of 171 mEq/L with a concomittant urine osmolality of 131 mOsm/kg. Molecular genetic analysis demonstrated that the patient had an AVPR2 mutation (c.861C > G) resulting in a substitution of tryptophan for serine at amino acid position 167 (p.Ser167Trp). His mother was heterozygous for the same Ser167Trp mutation which was found to be de novo from the DNA analysis of the maternal grandparents.

Management patterns of childhood-onset nephrotic syndrome.

As an initial effort to identify opportunities to improve the management of children with nephrotic syndrome, the goal of this study was to assess the present-day management of children with primary nephrotic syndrome. A web-based survey was designed to assess the current management styles of all pediatric nephrology faculties at ten participating institutions. Ninety-one percent completed the initial survey. The duration of initial glucocorticoid therapy ranged from 4 to 24 weeks. Physicians reported that the recommendation for kidney biopsy was dependent on the response to initial corticosteroid therapy, with the minority always recommending a biopsy for frequently relapsing or steroid-dependent cases. All responding physicians recommended a kidney biopsy in steroid-resistant cases. Treatment strategies were reported to vary based upon the steroid response pattern and, where available, kidney histopathology. Striking variations in therapeutic preferences were described when alternatives to glucocorticoids were considered. The variability of management practices among pediatric nephrologists in the USA combined with the changing characteristics of our pediatric population raise concerns about our future strategies for improving healthcare for children coping with nephrotic syndrome. This variability is not unique to children's healthcare or to nephrology. However, a systematic approach to patient care and improvement in health outcomes has been shown to substantially improve morbidity and mortality outcomes in children with chronic health conditions.

Management of childhood onset nephrotic syndrome.

The therapeutic approach to childhood nephrotic syndrome is based on a series of studies that began with an international collaborative effort sponsored by the International Study of Kidney Disease in Children in 1967. The characteristics of children presenting with nephrotic syndrome have changed over recent decades with greater frequency of the challenging condition focal segmental glomerulosclerosis and a greater prevalence of obesity and diabetes mellitus, which may be resistant to glucocorticoids in the former and exacerbated by long-term glucocorticoid therapy in the latter 2 conditions. The Children's Nephrotic Syndrome Consensus Conference was formed to systematically review the published literature and generate a children's primary nephrotic syndrome guideline for use in educational, therapeutic, and research venues.

Cranberry use among pediatric nephrology patients.

INTRODUCTION: Recurrent urinary tract infections are common in children, and the use of complementary therapies is common in other children with recurrent illnesses. However, little is known about the use of cranberry products by children with renal disease. We hypothesized that, because cranberry is often used to prevent urinary tract infections (UTI) in adult women, many parents would give it to their children, particularly to children prone to recurrent UTI (rUTI). METHODS: Anonymous, cross-sectional, self-administered survey of parents of children seen in the pediatric nephrology clinic at Brenner Children's Hospital between June 1, 2004, and August 13, 2004. RESULTS: Of the 117 parents surveyed, the patients' average age was 10.3 years, and 15% reported rUTI as a problem. Overall, 29% of surveyed parents gave cranberry products therapeutically; as expected, use was higher among those with rUTI (65%) than among those with other renal conditions (23%); odds ratio = 6.1 (2.0, 18.4, P < .001); many parents gave cranberry to treat as well as prevent diverse renal problems. Most felt it was beneficial and only 1 parent reported a side effect (nausea). Only 23% of those who used it had discussed cranberry use with their physician. CONCLUSION: Cranberry is commonly used therapeutically among patients seen in a pediatric nephrology clinic and is perceived as useful by parents, though uncommonly discussed with physicians. Randomized controlled trials are needed to determine the effectiveness of cranberry juice therapy for rUTI in children.

Renovascular disease in children and adolescents.

PURPOSE: This retrospective review describes the surgical management of renovascular disease in 25 consecutive children and adolescents with severe hypertension. METHODS: Patients 95 th percentile systolic or diastolic pressure adjusted for gender, age, and height). RA repair comprised 25 bypasses (73%) consisting of 28% saphenous vein, 60% hypogastric artery, and 12% polytetrafluoroethylene; 2 patch angioplasties (6%), and 7 reimplantations (21%). Branch RA exposure was required in 28 kidneys (88%), and branch reconstruction was required in 61%. Warm in situ repair was used in 53%, in situ cold perfusion in 24%, and ex vivo cold perfusion in 23%. Of six bilateral RA repairs, one was staged and two patients are awaiting a staged repair. Combined aortic reconstruction was required in three patients. No unplanned nephrectomy was performed. There were no perioperative deaths. Hypertension was cured in 36%, improved in 56%, and failed in 8% at mean follow-up of 46.4 +/- 7.8 months. The mean calculated glomerular filtration rate increased from 82.0 mL/min/1.73 m 2 preoperatively to 98.2 mL/min/1.73 m 2 postoperatively. The postoperative patency of 30 RA reconstructions was evaluated by angiography, RDS scanning, or both. At mean follow-up of 32.8 months (median, 21.2 months), primary RA patency was 91%. No failures were observed after 2 months follow-up. Estimated survival was 100% at 60 months, with one death 9 years after surgery. CONCLUSIONS: Renovascular hypertension in children and adolescents was caused by a heterogeneous group of lesions. All patients had RA repair, with arterial autografts in most of the RA bypasses. Cold perfusion preservation was used in half of the complex branch RA repairs. These strategies provided 91% primary patency at mean follow-up of 32.8 months, with beneficial blood pressure response in 92%. Surgical repair of clinically significant renovascular disease in children and adolescents is supported by these results.

Kidney and pancreas transplantation at Wake Forest University Baptist Medical Center.

More than 1,100 transplants have been performed at WFUBMC, including 60 pediatric transplants and 40 pancreas transplants. The one-year living donor kidney graft survival rate exceeds 90% and the 2 year deceased donor kidney graft survival rate exceeds 80%. The current active waiting list includes more than 300 candidates. Despite more transplants being performed, we continue to under-serve our referral area, which has among the highest rates of hypertension, diabetes, and end stage renal disease in the country. The AOTP has experienced a period of rapid growth over the past 2 years based upon sharing of zero HLA antigen-mismatched kidneys, use of ECD kidneys, liberalization of donor and recipient selection criteria, and the continued development of the pancreas transplant and laparoscopic donor nephrectomy programs. The pancreas transplant program will continue to grow as the waiting list enlarges and matures, with a 200% increase in activity expected within the next few years. The LDKT program will expand as more emphasis is placed on our pretransplant practice, including the more liberal application of laparoscopic donor nephrectomy, which has now become a standard procedure at our WFUBMC is involved in a number of clinical research projects studying new immunosuppressive agents and regimens. In this chapter, we have presented our recent experience with KTX in the elderly, ECD kidneys, alternate day Thymoglobulin administration, valganciclovir prophylaxis, SRL conversion using daclizumab bridge therapy, and pancreas transplantation with portal-enteric drainage. We plan to initiate a number of new protocols in the immediate future, including desensitization of the highly sensitized patient, ABO incompatible transplantation, transplantation of the HIV-positive patient, steroid withdrawal and avoidance regimens, living kidney donation from the anonymous altruistic donor, paired kidney exchanges from living donors, and islet transplantation. WFUBMC remains the most active donor hospital in North Carolina, and a non-heart beating donor protocol has been successfully initiated at our facility. Although much has been accomplished, a number of challenges remain. We look forward to building on our accomplishments, confronting the challenges, and achieving a level of excellence that could only be attained by mutual commitment from a dedicated, multidisciplinary team.