Renal transplantation in 4 patients with methylmalonic aciduria: a cell therapy for metabolic disease.

INTRODUCTION: Patients with methylmalonic acidemia (MMA) may develop many complications despite medical treatment, in particular, severe central nervous system damage and chronic kidney disease (CKD). A kidney transplant may partially correct the metabolic dysfunctions. Liver, kidney and combined liver-kidney transplantations have been advocated but no guidelines are available to identify the most suitable organ to transplant. PATIENTS AND METHODS: Four patients with MMA (mut° phenotype) received a kidney graft because of repeated metabolic decompensations, with progression to CKD in 3 patients (end-stage kidney disease in two patients and CKD stage III in one patient with an estimated glomerular filtration rate [eGFR] of 40ml/min/1.73m(2)) but normal renal function in one (eGFR of 93ml/min/1.73m(2)) before transplantation. RESULTS: The medium age at transplantation was 7.9y (5-10.2) and the median follow-up was 2.8years (1.8-4.6). Renal transplantation improved the relevant metabolic parameters in 4/4 patients and renal function in the patients with CKD. Plasma and urinary MMA levels immediately decreased and remained normal or subnormal (mean values of plasma MMA before transplantation 1530µmol/L versus 240µmol/L after transplantation, and mean values of urine MMA before transplantation 4700mmol/mol creatinine versus 2300mmol/mol creatinine after transplantation). No further acute metabolic decompensation was observed and protein-intake was increased from 0.60 to 0.83g/Kg/day. One patient transplanted at age 9.7years developed a hepatoblastoma at age 11years with subsequent neurological complications and eventually died. The three other patients are alive. Two of them remained neurologically stable. The 3rd patient who displayed choreoathetosis transiently improved his neurological condition immediately after transplantation and then remained stable. CONCLUSION: Kidney transplantation represents an interesting alternative therapeutic option in methylmalonic aciduria, for renal complications but also as a "cellular therapy" that may significantly reduce metabolic decompensations and hospitalizations. However, further neurological impairment remains possible.

Anti-Factor H autoantibodies in a fifth renal transplant recipient with atypical hemolytic and uremic syndrome.

Hemolytic uremic syndrome (HUS) associated with anti-Factor H (anti-FH) autoantibodies is a recently described pathophysiological entity. Monitoring of anti-FH IgG titer may be a sensitive marker of disease activity and guide treatment to eliminate circulating anti-FH antibodies. We report here a case of atypical HUS (aHUS) in which anti-FH autoantibodies were detected during the course of a fifth kidney transplant, 30 years after the first flare of aHUS. This exceptional case suggests that early, specific management based on immunosuppressive therapy and plasma exchanges monitored by anti-FH IgG titer may result in long-term graft survival.

Liver hepatoblastoma and multiple OXPHOS deficiency in the follow-up of a patient with methylmalonic aciduria.

A boy who was diagnosed with methylmalonic aciduria (MMA) at the age of 10 days developed persistent hepatomegaly and raised transaminases from the age of 4 years. He was subsequently diagnosed with Leigh syndrome and required a kidney transplantation for end-stage renal failure. A massive hepatoblastoma led to his death by the age of 11 years. Methylmalonyl-CoA mutase activity was undetectable on both cultured skin fibroblasts and kidney biopsy and multiple respiratory chain deficiency was demonstrated in the kidney. Mitochondrial dysfunction and/or post-transplant immunosuppressive therapy should be considered as a possible cause of liver cancer in this patient.

Urological complications after renal transplantation using ureteroureteral anastomosis in children.

PURPOSE: Ureterovesical reimplantation is most often performed for renal transplantation in children. We reviewed our experience to evaluate the safety and efficacy of ureteroureteral reimplantation in pediatric renal transplantation. MATERIALS AND METHODS: We retrospectively evaluated the charts of 92 boys and 72 girls who underwent a total of 166 ureteroureteral anastomoses for renal transplantation from January 1990 to December 1999. Spatulated end-to-end anastomosis was performed between recipient and graft ureters without stenting and with a bladder catheter for at least 10 days. RESULTS: Mean patient age at transplantation was 11.2 years (range 1 to 21.5). There were 22 living related donor and 144 cadaveric grafts. Urological anomalies and nephropathy were the cause of end stage renal disease in 146 and 20 patients, respectively. Urological complications were noted in 14 of the 166 transplantations (8.4%) in 10 boys and 4 girls, including 12 initial and 2 repeat grafts from 2 living related and 12 cadaveric donors. Five of these patients had undergone previous urological surgery. The 2 children (1.2%) with acute ureteral obstruction underwent repeat intervention after stent failure. Anastomotic leakage in 7 cases (4.2%) was treated conservatively in 1 and with a Double-J stent (Medical Engineering Corp., New York, New York) only required in 3. Reoperation was required in 3 cases. One patient (0.6%) with late ureteral stenosis underwent repeat anastomosis, 1 (0.6%) required reimplantation for recurrent pyelonephritis due to vesicoureteral reflux in the graft, 1 (0.6%) with a valve bladder required bladder augmentation and ureteral reimplantation, and 1 (0.6%) with lymphocele and 1 (0.6%) with lithiasis were successfully treated conservatively. Complications were associated with acute rejection in 6 cases. Mean followup without graft loss in patients who presented with versus without complications was 58.3 months (range 1 to 112) versus 75 (range 1 to 118). In the former patients with a mean age of 16 years 9 months versus those without urological complications mean serum creatinine was 116 and 108 mol./l., respectively. Two grafts were lost in patients with urological complications, including 1 who died of pulmonary embolism and 1 with refractory chronic rejection. Seven patients were lost to followup after 54 months (range 12 to 113) of adequate graft function. CONCLUSIONS: Ureteroureteral anastomosis is a safe and effective technique for pediatric renal transplantation with a low complication rate, which may be due to better vascularization of the shorter ureteral end of the graft. Our results should encourage the use of this technique in pediatric renal transplantation. Efforts to preserve the recipient ureters should be made at nephrectomy.

[Analgesia with oxygen-nitrous oxide mixture during percutaneous renal biopsy in children]. / Analgésie par le protoxyde d'azote pour la réalisation de la biopsie rénale percutanée chez l'enfant.

UNLABELLED: The efficacy of an inhaled equimolar mixture of nitrous oxide and oxygen (Entonox/MEOPA) to prevent procedural pain during renal percutaneous biopsies in children was assessed. PATIENTS AND METHODS: One hundred and seven children who underwent 113 renal biopsies during a 17-month period were included in a prospective uncontrolled pediatric study. Efficacy was evaluated using patients' answers to a questionnaire and nurses' observations. RESULTS: Pain was absent in 86.5% of the cases. Mild adverse events were noted in one-third of the procedures, and were always reversible within a few minutes when the inhalation stopped. Acceptability was good. The use of this gas is easy and safe provided a few precautions are observed. CONCLUSION: Inhaled equimolar mixture of nitrous oxide and oxygen prevents procedural pain during renal percutaneous biopsies.

PAX2 mutations in oligomeganephronia.

BACKGROUND: Oligomeganephronia (OMN) is a rare congenital and usually sporadic anomaly. It is characterized by bilateral renal hypoplasia, with a reduced number of enlarged nephrons. The mechanisms involved in this deficient nephrogenesis are unknown. The paired box transcription factor PAX2 plays a fundamental role in renal development. Heterozygous Pax2 mutants in mice are characterized by renal hypoplasia and retinal defects, and in humans, PAX2 mutations have been described in the renal-coloboma syndrome. METHODS: To assess whether OMN could be related to PAX2, we searched for PAX2 mutations in nine patients presenting with sporadic and apparently isolated OMN. RESULTS: Heterozygous PAX2 mutations were found in three patients. A limited optic nerve coloboma was secondarily detected in two cases and a very mild optic disk dysplasia in one patient. None of these patients had visual impairment. CONCLUSIONS: Ocular anomaly and PAX2 mutations should be sought in all patients with OMN.

Long term results of liver-kidney transplantation in children with primary hyperoxaluria.

From 1990 to 2000, we performed eight liver-kidney transplants in eight children, aged 1-16 years, with end-stage renal failure (ESRF) due to primary hyperoxaluria (PH1). The duration of dialysis before transplantation ranged from 2 to 42 months (mean 14 months) and was <1 year in four patients. Only the first patient underwent postoperative hemodialysis; in the other five, we chose to induce maximal diuresis from the first hours with intravenous and intragastric hyperhydration (> or =3 l/m2 per day). High water intake with nocturnal tube hydration was maintained for 6 months to 5 years, as long as oxaluria exceeded 0.5 mmol/day. A quadruple sequential immunosuppressive regimen was used. Two patients died during liver graft surgery. The other six patients are alive and well, with a mean follow-up of 7.4 years (range 5-11 years). Patient and graft survival is 75% at 5 years. At latest follow-up, liver tests were normal in all six patients; creatinine clearance ranged from 55 to 95 ml/min per 1.73 m2 (mean=74). Oxaluria was lower than 0.4 mmol/day in all patients (mean=0.22). The six patients underwent 15 renal biopsies, 1-11 years after transplantation. Chronic transplant nephropathy was present in four patients and mild cyclosporin nephrotoxicity in another. No oxalate crystals were seen and repeat ultrasonography has been consistently normal in all patients. The three patients with bone oxalosis showed progressive complete healing of bone lesions. All six children or adolescents now live a normal life. From this series, we conclude that early combined liver-kidney transplantation is the treatment of choice for children with ESRF due to primary hyperoxaluria.

One-year routine renal transplant biopsies in children.

In our institution, systematic renal graft biopsies are performed 1 year after transplantation before deciding to switch to alternate-day steroid therapy, which has been shown to be beneficial for statural growth. We analyzed the results of systematic graft biopsies in 145 children with a creatinine clearance > or =45 ml/min per 1.73 m2. Biopsies were classified according to Banff diagnostic categories. Normal parenchyma was observed in 19 cases (13%), non-specific lesions in 42 cases (29%), chronic allograft nephropathy grade 1-3 in 68 cases (49%), and acute rejection in 8 cases (5%). Clinicopathological correlations indicated that patients with chronic allograft nephropathy had received kidneys from older donors, with longer cold ischemia time and with a higher incidence of delayed graft function. There was a strong correlation between the donor age and the presence of vascular lesions. There was also a good correlation between the severity of histological lesions and the occurrence of acute rejection episodes during the 1st year after transplantation. Renal function remained stable for up to 10 years in patients with normal parenchyma or non-specific lesions, while serum creatinine levels increased after the 2nd year in patients with chronic allograft nephropathy.

WT1 splice-site mutations are rarely associated with primary steroid-resistant focal and segmental glomerulosclerosis.

BACKGROUND: Donor splice-site de novo heterozygous mutations in intron 9 of the Wilms' tumor gene (WT1) have been reported in Frasier syndrome, which is defined by the association of focal and segmental glomerulosclerosis (FSGS), male pseudohermaphroditism, and gonadoblastoma. These splice-site mutations alter the WT1 alternative splicing leading to two WT1 isoforms, with (+) or without (-) three amino acids, lysine-threonine-serine (KTS), between zinc fingers 3 and 4. The aim of this work was to investigate the possibility that some cases of primary steroid-resistant nephrotic syndrome associated with FSGS may be caused by WT1 splice-site mutations. METHODS: We analyzed WT1 exons 8 and 9 and the surrounding exon/intron boundary DNA sequences in 37 children with nonfamilial primary steroid-resistant nephrotic syndrome. Semiquantitative reverse transcription-polymerase chain reaction (RT-PCR) was used to determine the relative ratio of +KTS/-KTS transcripts from immortalized lymphocyte RNA. RESULTS: One boy with FSGS and associated pathologies (diaphragmatic hernia, proximal hypospadias, and unilateral testicular ectopia) was found to carry the heterozygous 1228 +4 C-->T splice-site mutation. RT-PCR quantitation of the +KTS/-KTS transcripts from immortalized lymphocyte RNA of this patient showed a diminution of the +KTS/-KTS isoform ratio (0.43), which is identical to that reported in patients with Frasier syndrome. Using the same approach, healthy control subjects have +KTS/-KTS ratios ranging from 1.50 to 2.00. CONCLUSIONS: This study expands the range of the phenotypic presentation of the intron 9 splice-site WT1 mutations and adds to the already reported heterogeneity of primary steroid-resistant nephrotic syndromes. We suggest that these mutations are not likely to be a common cause of isolated steroid-resistant nephrotic syndrome, and recommend a WT1 exon 9/intron 9 splice-site study in children with primary steroid-resistant nephrotic syndrome if genital or diaphragmatic anomalies are associated. The identification of such WT1 mutations has practical implications for the management of these patients.

Genetics of the nephrotic syndrome.

There are a large number of glomerular diseases that may be responsible for a nephrotic syndrome, the most frequent in childhood being minimal change disease. In the past few years, the molecular genetic basis of several conditions that may cause a nephrotic syndrome have been identified. Denys-Drash syndrome and Frasier syndrome are related diseases caused by mutations in the WT1 gene. Familial forms of idiopathic nephrotic syndrome with focal and segmental glomerular sclerosis/hyalinosis have been identified with an autosomal dominant or recessive mode of inheritance and linkage analysis have allowed to localize several genes on chromosomes 1, 11 and 17. The gene responsible for the Finnish type congenital nephrotic syndrome has been identified. This gene, named NPHS1, codes for nephrin, which is located at the slit diaphragm of the glomerular podocytes and is thought to play an essential role in the normal glomerular filtration barrier.

Treatment of lupus nephritis in children.

In children, systemic lupus erythematosus (SLE) is often more severe than in adults. Renal disease is very common in SLE, with clinical symptoms of renal involvement occurring in 30%-70% of patients. In the absence of appropriate treatment the child may die from the disease or progress rapidly to renal failure. However, aggressive treatment regimens, in particular corticosteroids, carry the risk of growth retardation, accelerated atherosclerosis, and severe infectious complications. Lupus nephritis is classified into six groups depending on the severity of the histological lesions. The most-appropriate treatment for optimal efficacy with minimal side-effects depends on the disease severity. Mild lesions (class I or II) require only careful follow-up to identify any disease progression. Patients with class III nephropathy (focal and segmental glomerulonephritis) may have mild clinical symptoms, in which case no specific therapy is indicated, or more-severe symptoms of the nephrotic syndrome, hypertension, and sometimes moderate renal insufficiency. These patients require the same aggressive therapy as those with class IV disease (diffuse proliferative glomerulonephritis). Our current protocol starts with three methylprednisolone pulses followed by 1.5 mg/kg per day oral prednisone and six monthly pulses of cyclophosphamide. After a second renal biopsy the patient may be maintained on azathioprine while the prednisone dosage is slowly tapered. In children with milder disease we use lower doses of oral prednisone (1-1.5 mg/kg per day). Patients with membranous glomerulonephritis (class V) require no specific therapy if they have pure membranous nephropathy, but require aggressive therapy if they have the nephrotic syndrome. In those patients who progress to end-stage renal disease, clinical and serological remission is common and renal transplantation can be performed, as recurrence in the transplant is very rare.

[Rheumatoid purpura]. / Purpura rhumatoïde.

Schönlein-Henoch purpura is a clinical syndrome characterized by the association of skin, joint and gastrointestinal symptoms consisting respectively in purpura, arthralgia and abdominal pain. The incidence of renal symptoms ranges from 33 to 50%. The long term prognosis is related to the renal disease which is characterized by a glomerular involvement, with hematuria and sometimes proteinuria. In more severe cases, a nephrotic syndrome is present with a decrease in renal function. A renal biopsy is performed when proteinuria is in excess of 1 g/day. It shows a mesangial proliferation and in more severe cases extracapillary proliferation while mesangial IgA deposits are seen by immunofluorescence. Severe forms require a treatment with corticosteroids, started with methylprednisolone pulses. Treatment should be started early in the course of the disease before glomerular crescents become fibrous.

Diabetes mellitus in patients with infantile cystinosis after renal transplantation.

Diabetes mellitus is a frequent long-term complication of infantile nephropathic cystinosis. We studied 44 cystinotic patients, aged 22.1+/-5.4 years, transplanted at a mean age of 11.3+/-2.5 years; 25% were treated with insulin at 20 years of age or 10 years after transplantation, and over half required insulin at latest follow-up. In comparison, diabetes mellitus occurred in only 1% of non-cystinotic transplanted patients. Sequential oral glucose tolerance tests (OGTTs) in these patients showed the progressive deterioration of glucose metabolism. All but 2 patients had an abnormal response at latest follow-up. The high doses of corticosteroid given after transplantation or during rejection episodes were responsible for transient insulin dependency. However, the development of impaired glucose tolerance and diabetes mellitus depended mainly on the cystinotic process, which developed slowly with time. The deterioration of glucose tolerance was correlated with a decreased early phase of insulin secretion, estimated from the plasma insulin level at 30 min of the OGTT, while there was no evidence of insulin resistance. The occurrence of diabetes mellitus correlated with a worsening of the vital prognosis.

The same mutation affecting the splicing of WT1 gene is present on Frasier syndrome patients with or without Wilms' tumor.

Denys-Drash and Frasier syndromes are rare human disorders that associate nephropathy with gonadal and genital abnormalities. In DDS there is a predisposition to Wilms' tumor. Heterozygous point mutations in the Wilms' tumor, type1 gene (WT1), particularly those altering the zinc finger (ZF) encoding exons, have been reported in most DDS patients, while mutations in intron 9 of the same gene cause FS. This paper describes two cases of DDS, one FS and one patient with Wilm's tumor and intersex genitalia, in which mutations were searched by sequencing the exons 8 and 9 of WT1 gene. Patient 1 carried a missense point mutation in exon 8 (ZF2), converting a CGA-Arg codon to a TGA-stop codon. Patient 2 presented a single nucleotide deletion within exon 9 (ZF3) introducing a premature chain termination at codon 398. Patients 3 and 4 had a C-->T transition at position +4 of the second alternative splice donor site of exon 9 (this mutation was detected in peripheral blood and in tumor derived DNA of patient 3). However, patient 3 had previously developed a Wilms' tumor. This is the first case of Wilms' tumor development in a phenotypically and genetically confirmed case of FS.

Renal granulomatous sarcoidosis in childhood: a report of 11 cases and a review of the literature.

UNLABELLED: We analysed retrospectively 11 children with renal granulomatous sarcoidosis confirmed by renal histology in order to describe the course and prognosis of the disease. Symptomatic sarcoidosis was diagnosed at a mean age of 10.1 years. Nine children had renal involvement at the time of diagnosis. In the course of the disease, nine patients developed renal failure and mild proteinuria, seven had transient sterile leukocyturia, four showed microscopic haematuria, seven had a urinary concentrating defect, and enlarged kidneys were seen in three patients. One child had hypercalcaemia and hypercalciuria, none had hypertension. Light microscopy of the kidney showed interstitial infiltration by mononuclear cells in all children, interstitial fibrosis in nine patients, epithelioid granulomas in seven, tubular involvement in eight, and mild glomerular involvement in seven patients. Renal immunofluorescence was negative. Ten children received prednisone for 1-11 years. After a mean follow up of 5.5 years, three patients had entered end-stage renal failure and one had chronic insufficiency after interruption of medical supervision and prednisone therapy. CONCLUSION: Renal failure, proteinuria, leukocyturia, haematuria, and concentration defect are the prominent features of renal granulomatous sarcoidosis in children. Steroid therapy, adjusted according to disease activity, may prevent end-stage renal failure.

WT1 and PAX-2 podocyte expression in Denys-Drash syndrome and isolated diffuse mesangial sclerosis.

Denys-Drash syndrome is a rare disorder of urogenital development characterized by the association of early onset glomerulopathy caused by diffuse mesangial sclerosis, gonadal dysgenesis leading to pseudohermaphroditism in males, and a high risk of developing Wilms' tumor. The syndrome is caused by dominant negative point mutations in the WT1 gene that encodes a tumor suppressor transcription factor normally expressed in podocytes. Mutations usually affect the zinc fingers of the WT1 protein. The basic defect is unknown in most cases of isolated diffuse mesangial sclerosis, a disease characterized by the same glomerular changes as in Denys-Drash syndrome but possibly transmitted as an autosomal recessive trait. Here we show that the distribution of WT1 is abnormal in most patients with Denys-Drash syndrome : WT1 nuclear staining of podocytes is decreased or absent. This finding is consistent with the decreased DNA binding capacity of the mutated protein. One target gene of WT1 is PAX2, the expression of which is down-regulated in podocytes during early stages of nephrogenesis. We demonstrate that WT1 mislocalization is associated with abnormal podocyte expression of PAX2 protein and RNA. We suggest that persistent expression of PAX2 is likely to result from the loss of WT1 dependent transcriptional repression and may participate in the pathological mechanisms leading to glomerular dysfunction. Abnormal distribution of WT1 and PAX2 was also observed in isolated diffuse mesangial sclerosis suggesting that a defect in WT1 could also be operative in isolated diffuse mesangial sclerosis. Primary involvement of PAX2 is an alternative hypothesis because persistent expression of PAX2 in transgenic mice is associated with the occurrence of early and severe glomerulopathy.

[Treatment of lupus nephritis in children]. / Traitement de la néphropathie du lupus érythémateux disséminé chez l'enfant.

The severity of renal disease in systemic lupus erythematosus is variable. Renal biopsy is important to guide the treatment. The World Health Organization classification define six different histological categories with possible transformations from one category to another. Histological signs of activity or chronicity are important with respect to prognosis and treatment. Examination of renal biopsy allows predicting the reversibility of histological lesions following therapy. Apart from histological signs of severity, other factors may influence the prognosis: arterial hypertension, initial serum creatinine, the delay between onset of renal disease and treatment, the occurrence of exacerbations of the nephropathy, and the response to therapy by the end of the first year. The prognosis of severe forms of lupus nephritis, mainly diffuse proliferative glomerulonephritis, has improved during the last 20 years. The addition of immunosuppressive agents (cyclophosphamide, azathioprine) to corticosteroids is responsible for this improvement. Methylprednisolone pulses are as effective as oral high doses of prednisone during initial treatment and have fewer side effects. Many authors advocate monthly cyclophosphamide pulses over six months, sometimes followed by quarterly pulse cyclophosphamide. However, such an approach has not been proven to be more effective than an oral course of cyclophosphamide and/or azathioprine. On follow-up, steroid therapy should be slowly tapered, and close monitoring of lupus serological parameters (anti-DNA antibodies, complement), urinary protein excretion rate, urinary sediment and renal function allow one to detect exacerbations of the disease, which may require adapted therapy. While such protocols have improved the outcome, they have potential side effects. In addition to the deleterious effect of steroids on physical appearance, often badly tolerated by adolescents, immunosuppressive treatments increase the risks of severe infectious complications and the risks of cardiovascular complications in young adults.