Luisa Murer

COQ2 Nephropathy: A Newly Described Inherited Mitochondriopathy with Primary Renal Involvement

Primary coenzyme Q(10) (CoQ(10)) deficiency includes a group of rare autosomal recessive disorders primarily characterized by neurological and muscular symptoms. Rarely, glomerular involvement has been reported. The COQ2 gene encodes the para-hydroxybenzoate-polyprenyl-transferase enzyme of the CoQ(10) synthesis pathway. We identified two patients with early-onset glomerular lesions that harbored mutations in the COQ2 gene. The first patient presented with steroid-resistant nephrotic syndrome at the age of 18 months as a result of collapsing glomerulopathy, with no extrarenal symptoms. The second patient presented at five days of life with oliguria, had severe extracapillary proliferation on renal biopsy, rapidly developed end-stage renal disease, and died at the age of 6 months after a course complicated by progressive epileptic encephalopathy. Ultrastructural examination of renal specimens from these cases, as well as from two previously reported patients, showed an increased number of dysmorphic mitochondria in glomerular cells. Biochemical analyses demonstrated decreased activities of respiratory chain complexes [II+III] and decreased CoQ(10) concentrations in skeletal muscle and renal cortex. In conclusion, we suggest that inherited COQ2 mutations cause a primary glomerular disease with renal lesions that vary in severity and are not necessarily associated with neurological signs. COQ2 nephropathy should be suspected when electron microscopy shows an increased number of abnormal mitochondria in podocytes and other glomerular cells.

Broadening the Spectrum of Diseases Related to Podocin Mutations

A total of 179 children with sporadic nephrotic syndrome were screened for podocin mutations: 120 with steroid resistance, and 59 with steroid dependence/frequent relapses. Fourteen steroid-resistant patients presented homozygous mutations that were associated with early onset of proteinuria and variable renal lesions, including one case with mesangial C3 deposition. Single mutations of podocin were found in four steroid-resistant and in four steroid-dependent; five patients had the same mutation (P20L). Among these, two had steroid/cyclosporin resistance, two had steroid dependence, and one responded to cyclosporin. The common variant R229Q of podocin, recently associated with late-onset focal segmental glomerulosclerosis, had an overall allelic frequency of 4.2% versus 2.5% in controls. To further define the implication of R229Q, a familial case was characterized with two nephrotic siblings presenting the association of the R229Q with A297V mutation that were inherited from healthy mother and father, respectively. Immunohistochemistry with anti-podocin antibodies revealed markedly decreased expression of the protein in their kidneys. All carriers of heterozygous coding podocin mutation or R229Q were screened for nephrin mutation that was found in heterozygosity associated with R229Q in one patient. Finally, podocin loss of heterozygosity was excluded in one heterozygous child by characterizing cDNA from dissected glomeruli. These data outline the clinical features of sporadic nephrotic syndrome due to podocin mutations (homozygous and heterozygous) in a representative population with broad phenotype, including patients with good response to drugs. The pathogenetic implication of single podocin defects per se in proteinuria must be further investigated in view of the possibility that detection of a second mutation could have been missed. A suggested alternative is the involvement of other gene(s) or factor(s).

Infantile encephalomyopathy and nephropathy with CoQ10 deficiency: a CoQ10-responsive condition.

Coenzyme Q10 (CoQ10) deficiency has been associated with various clinical phenotypes, including an infantile multisystem disorder. The authors report a 33-month-old boy who presented with corticosteroid-resistant nephrotic syndrome in whom progressive encephalomyopathy later developed. CoQ10 was decreased both in muscle and in fibroblasts. Oral CoQ10 improved the neurologic picture but not the renal dysfunction.

Antibiotic treatment for pyelonephritis in children: multicentre randomised controlled non-inferiority trial

Objective To compare the efficacy of oral antibiotic treatment alone with treatment started parenterally and completed orally in children with a first episode of acute pyelonephritis. Design Multicentre, randomised controlled, open labelled, parallel group, non-inferiority trial. Setting 28 paediatric units in north east Italy. Participants 502 children aged 1 month to <7 years with clinical pyelonephritis. Intervention Oral co-amoxiclav (50 mg/kg/day in three doses for 10 days) or parenteral ceftriaxone (50 mg/kg/day in a single parenteral dose) for three days, followed by oral co-amoxiclav (50 mg/kg/day in three divided doses for seven days). Main outcomes measures Primary outcome was the rate of renal scarring. Secondary measures of efficacy were time to defervescence (<37�C), reduction in inflammatory indices, and percentage with sterile urine after 72 hours. An exploratory subgroup analysis was conducted in the children in whom pyelonephritis was confirmed by dimercaptosuccinic acid (DMSA) scintigraphy within 10 days after study entry. Results Intention to treat analysis showed no significant differences between oral (n=244) and parenteral (n=258) treatment, both in the primary outcome (scarring scintigraphy at 12 months 27/197 (13.7%) v 36/203 (17.7%), difference in risk −4%, 95% confidence interval −11.1% to 3.1%) and secondary outcomes (time to defervescence 36.9 hours (SD 19.7) v 34.3 hours (SD 20), mean difference 2.6 (−0.9 to 6.0); white cell count 9.8�109/l (SD 3.5) v 9.5�109/l (SD 3.1), mean difference 0.3 (−0.3 to 0.9); percentage with sterile urine 185/186 v 203/204, risk difference −0.05% (−1.5% to 1.4%)). Similar results were found in the subgroup of 278 children with confirmed acute pyelonephritis on scintigraphy at study entry. Conclusions Treatment with oral antibiotics is as effective as parenteral then oral treatment in the management of the first episode of clinical pyelonephritis in children. Trial registration Clinical Trials NCT00161330.

Recurrence of focal segmental glomerulosclerosis after renal transplantation in patients with mutations of podocin.

BACKGROUND Posttransplant recurrence of focal segmental glomerulosclerosis (FSGS) occurs in a relevant proportion of FSGS patients and represents an important clinical emergency. It is taken as a proof of the existence of circulating permeability plasma factor(s) that are also putative effectors of original proteinuria in these patients. Familial forms of FSGS do not recur, but the discovery of numerous patients with sporadic FSGS and mutations of podocin (NPHS2, that is actually an inherited disease) who received a renal graft require a re-evaluation of the problem. METHODS To evaluate the incidence of posttransplant recurrence of FSGS in patients with NPHS2, the authors screened for podocin mutations in 53 patients with the clinical and pathologic stigmata of FSGS who had renal failure and who had undergone renal transplantation.Results. Twelve children were found to carry a homozygous (n9) or a heterozygous (n4) mutation of podocin and were classified, according to current criteria, as patients with inherited FSGS. In 5 patients of this group (38%), proteinuria recurred after renal graft and in 2, renal biopsy results showed recurrence of FSGS. Prerecurrence serum of 3 patients of this cohort was tested for antipodocin antibodies with indirect immuno-Western utilizing human podocyte extracts and were found negative. The rate of FSGS recurrence was comparable in non-NPHS2-FSGS children (12 of 27) and adults (3 of 13). Also clinical outcome of recurrence and response to plasmapheresis and immunosuppressors were comparable, suggesting a common mechanism. CONCLUSION These data show a high rate of FSGS recurrence in patients with NPHS2 mutations that is comparable with idiopathic FSGS and describe the successful therapeutic approach. Recurrence of an apparently inherited disease should stimulate a critical review of the mechanisms of recurrence and of original proteinuria in these cases.

Short-Term Effects of Rituximab in Children with Steroid- and Calcineurin-Dependent Nephrotic Syndrome: A Randomized Controlled Trial

BACKGROUND AND OBJECTIVES Prednisone and calcineurin inhibitors are the mainstay therapy of idiopathic nephrotic syndrome (INS) in children. However, drug dependence and toxicity associated with protracted use are common. Case series suggest that the anti-CD20 monoclonal antibody rituximab (RTX) may maintain disease remission. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS This open-label randomized controlled trial was powered to show that a strategy based on RTX and lower doses of prednisone and calcineurin inhibitors was noninferior to standard doses of these agents in maintaining 3-month proteinuria as low as baseline or up to 1 g/d greater (noninferiority margin). Participants were stratified by the presence of toxicity to prednisone/calcineurin inhibitors and centrally assigned to add RTX (Mabthera, 375 mg/m(2) intravenously) to lower doses of standard agents or to continue with current therapy alone. The risk of relapse was a secondary outcome. RESULTS Fifty-four children (mean age 11 ± 4 years) with INS dependent on prednisone and calcineurin inhibitors for >12 months were randomized. Three-month proteinuria was 70% lower in the RTX arm (95% confidence interval 35% to 86%) as compared with standard therapy arm (intention-to-treat); relapse rates were 18.5% (intervention) and 48.1% (standard arm) (P = 0.029). Probabilities of being drug-free at 3 months were 62.9% and 3.7%, respectively (P < 0.001); 50% of RTX cases were in stable remission without drugs after 9 months. CONCLUSIONS Rituximab and lower doses of prednisone and calcineurin inhibitors are noninferior to standard therapy in maintaining short-term remission in children with INS dependent on both drugs and allow their temporary withdrawal.

A Randomized Trial to Assess the Impact of Early Steroid Withdrawal on Growth in Pediatric Renal Transplantation: The TWIST Study

Minimizing steroid exposure in pediatric renal transplant recipients can improve linear growth and reduce metabolic disorders. This randomized multicenter study investigated the impact of early steroid withdrawal on mean change in height standard deviation score (SDS) and the safety and efficacy of two immunosuppressive regimens during the first 6 months after transplantation. Children received tacrolimus, MMF, two doses of daclizumab and steroids until day 4 (TAC/MMF/DAC, n=98) or tacrolimus, MMF and standard‐dose steroids (TAC/MMF/STR, n=98). Mean change in height SDS was 0.16 ± 0.32 with TAC/MMF/DAC and 0.03 ± 0.32 with TAC/MMF/STR. The mean treatment group difference was 0.13 (p < 0.005 [95% CI 0.04–0.22]), 0.21 in prepubertal (p = 0.009 [95% CI 0.05–0.36]) and 0.05 in pubertal children (p = ns). Frequency of biopsy‐proven acute rejection was 10.2%, TAC/MMF/DAC, and 7.1%, TAC/MMF/STR. Patient and graft survival and renal function were similar. Significantly greater reductions in total cholesterol and triglycerides but significantly higher incidences of infection and anemia were found with TAC/MMF/DAC (p < 0.05 all comparisons). Early steroid withdrawal significantly aided growth at 6 months more so in prepubertal than pubertal children. This was accompanied by significantly better lipid and glucose metabolism profiles without increases in graft rejection or loss.

Rituximab in Children with Resistant Idiopathic Nephrotic Syndrome

Idiopathic nephrotic syndrome resistant to standard treatments remains a therapeutic dilemma in pediatric nephrology. To test whether the anti-CD20 monoclonal antibody rituximab may benefit these patients, we conducted an open-label, randomized, controlled trial in 31 children with idiopathic nephrotic syndrome unresponsive to the combination of calcineurin inhibitors and prednisone. All children continued prednisone and calcineurin inhibitors at the doses prescribed before enrollment, and one treatment group received two doses of rituximab (375 mg/m(2) intravenously) as add-on therapy. The mean age was 8 years (range, 2-16 years). Rituximab did not reduce proteinuria at 3 months (change, -12% [95% confidence interval, -73% to 110%]; P=0.77 in analysis of covariance model adjusted for baseline proteinuria). Additional adjustment for previous remission and interaction terms (treatment by baseline proteinuria and treatment by previous remission) did not change the results. In conclusion, these data do not support the addition of rituximab to prednisone and calcineurin inhibitors in children with resistant idiopathic nephrotic syndrome.

Renal-retinal syndromes: Association of retinal anomalies and recessive nephronophthisis in patients with homozygous deletion of the NPH1 locus

Tapeto-retinal degeneration is frequent in patients with nephronophthisis. Association of the most severe forms of tapeto-retinal dystrophy with NPH identifies a syndrome described first by Senior et al and Loken et al. This syndrome is distinct on molecular grounds from pure renal nephronophthisis (NPH1), which has its gene locus mapped on chromosome 2q13. We describe three families with large homozygous deletion of the NPH1 locus in which mild to moderate ocular lesions due to tapeto-retinal degeneration coexisted and were correlated to renal defects. This new association of NPH1 with retinal dystrophy is characterized by focal lesions of retina and is pauci-symptomatic in clinical presentation. For this reason it may remain unrecognized in most NPH1 patients.

Rituximab in Children with Steroid-Dependent Nephrotic Syndrome: A Multicenter, Open-Label, Noninferiority, Randomized Controlled Trial

Steroid-dependent nephrotic syndrome (SDNS) carries a high risk of toxicity from steroids or steroid-sparing agents. This open-label, noninferiority, randomized controlled trial at four sites in Italy tested whether rituximab is noninferior to steroids in maintaining remission in juvenile SDNS. We enrolled children age 1-16 years who had developed SDNS in the previous 6-12 months and were maintained in remission with high prednisone doses (≥0.7 mg/kg per day). We randomly assigned participants to continue prednisone alone for 1 month (control) or to add a single intravenous infusion of rituximab (375 mg/m(2); intervention). Prednisone was tapered in both groups after 1 month. For noninferiority, rituximab had to permit steroid withdrawal and maintain 3-month proteinuria (mg/m(2) per day) within a prespecified noninferiority margin of three times the levels among controls (primary outcome). We followed participants for ≥1 year to compare risk of relapse (secondary outcome). Fifteen children per group (21 boys; mean age, 7 years [range, 2.6-13.5 years]) were enrolled and followed for ≤60 months (median, 22 months). Three-month proteinuria was 42% lower in the rituximab group (geometric mean ratio, 0.58; 95% confidence interval, 0.18 to 1.95 [i.e., within the noninferiority margin of three times the levels in controls]). All but one child in the control group relapsed within 6 months; median time to relapse in the rituximab group was 18 months (95% confidence interval, 9 to 32 months). In the rituximab group, nausea and skin rash during infusion were common; transient acute arthritis occurred in one child. In conclusion, rituximab was noninferior to steroids for the treatment of juvenile SDNS.