[Vaccine recommendations for children with idiopathic nephrotic syndrome]. / Recommandations vaccinales pour les enfants avec un syndrome néphrotique idiopathique.

The specific treatment of idiopathic nephrotic syndrome is based on corticosteroid therapy and/or steroid-sparing immunosuppressive agents in children who are steroid-dependant or frequent relapsers (60-70 %). Patients have an increased infectious risk not only related to the disease during relapses (hypogammaglobulinemia and urinary leakage of opsonins) but also to treatments (corticosteroids or immunosuppressive agents) in period of remission. Vaccination is therefore particularly recommended in these patients. Potential vaccine risks are ineffectiveness, induction of vaccine disease and relapse of idiopathic nephrotic syndrome. Only live vaccines expose to the risk of vaccine disease: they are in general contra-indicated under immunosuppressive treatment. The immunogenicity of inactivated vaccines is reduced but persists. The immunogenic stimulus of vaccination may in theory trigger a relapse of the nephrotic syndrome. Nevertheless, this risk is low in the literature, and even absent in some studies. The benefit-risk ratio is therefore in favor of vaccination with respect to the vaccination schedule for inactivated vaccines, with wide vaccination against pneumococcus and influenza annually. Depending on the context and after expert advice, immunization with live vaccines could be discussed if residual doses/levels of immunosuppressive treatments are moderate and immunity preserved.

C3 nephritic factor associated with C3 glomerulopathy in children.

BACKGROUND: C3 glomerulopathy (C3G) is characterized by predominant C3 deposits in glomeruli and dysregulation of the alternative pathway of complement. Half of C3G patients have a C3 nephritic factor (C3NeF). C3G incorporated entities with a range of features on microscopy including dense deposit diseases (DDD) and C3 glomerulonephritis (C3GN). The aim of this work was to study children cases of C3G associated with C3NeF. METHODS: We reviewed 18 cases of C3G with a childhood onset associated with C3NeF without identified mutations in CFH, CFI, and MCP genes. RESULTS: Clinical histories started with recurrent hematuria for seven patients, nephrotic syndrome for four, acute post-infectious glomerulonephritis for three and acute renal failure for four. Twelve patients had a low C3 at first investigation. Kidney biopsy showed ten C3GN and eight DDD. Twenty-three percent of the patients tested presented elevated sC5b9. Seven patients relapsed 3 to 6 years after the onset. At the end of follow-up, two patients were under dialysis, 11 had a persistent proteinuria, five had none; four patients did not follow any treatment. Steroids were first used in 80 % of cases. CONCLUSIONS: C3NeF associated C3G has a heterogeneous presentation and outcome. Anti-proteinuric agents may control the disease during follow-up, even after nephrotic syndrome at the onset. The efficiency of immunosuppressive therapy remains questionable.

Neurological involvement in a child with atypical hemolytic uremic syndrome.

We report the case of a 4-year-old boy, diagnosed with atypical hemolytic uremic syndrome (HUS) due to a hybrid factor H. He progressed to end-stage renal failure despite plasmatherapy and underwent bilateral nephrectomy because of uncontrolled hypertension. Three days after, he had partial complex seizures with normal blood pressure, normal blood count and normal magnetic resonance imaging (MRI), which recurred 1 month later. Eight months later, he had a third episode of seizures, with hemoglobin of 10 g/dl without schizocytes, low haptoglobin of 0.18 g/l, and moderate thrombocytopenia (platelets 98 × 10(9)/l). He remained hypertensive and deeply confused for 2 days. The third MRI showed bilateral symmetrical hyperintensities of the cerebral pedunculas, caudate nuclei, putamens, thalami, hippocampi, and insulae suggesting thrombotic microangiopathy secondary to a relapse of HUS rather than reversible posterior leukoencephalopathy syndrome (RPLS), usually occipital and asymmetrical. Plasmatherapy led to a complete neurological recovery within 2 days although hypertension had remained uncontrolled. The fourth MRI 10 weeks after, on maintenance plasmatherapy, was normal and clinical examination remained normal, except for high blood pressure. In conclusion, brain MRI allows differentiating thrombotic microangiopathy lesions from RPLS in atypical HUS, which is crucial since lesions may be reversible with plasmatherapy.

Pulse cyclophosphamide therapy and clinical remission in atypical hemolytic uremic syndrome with anti-complement factor H autoantibodies.

We report 3 children with atypical hemolytic uremic syndrome associated with anti-complement factor H (CFH) autoantibodies who presented with sustained remission with low antibody titers and normal kidney function after plasma exchanges (PEs) and cyclophosphamide pulses. The 3 children initially presented with acute vomiting, fatigue, gross hematuria, hypertension, hemolytic anemia, thrombocytopenia, nephrotic syndrome, and acute kidney injury. C3 levels were normal in patients 1 and 3 and low in patient 2 (0.376 mg/mL [0.376 g/L]). CFH antibody titers were increased (15,000 to > 32,000 arbitrary units [AU]). Patient 1, an 11-year-old boy, was treated with 12 PEs, leading to a decrease in CFH antibody titer (to 800 AU). A first relapse 1 month later was treated with 6 PEs and 4 rituximab infusions. A second relapse 3 months later required 5 PEs, and the patient received oral steroids (0.5 mg/d/kg body weight) and 5 cyclophosphamide pulses (1 g/1.73 m(2)), leading to sustained remission with normal kidney function (estimated glomerular filtration rate [eGFR], 120 mL/min/1.73 m(2) [2.0 mL/s/1.73 m(2)]) and a stable decrease in CFH antibody titer (to 2,000 AU) 3 years later. Patient 2, a 5-year-old boy, required dialysis therapy for 2 weeks. He received 3 plasma infusions without remission. Six PEs associated with 2 cyclophosphamide pulses (0.5 g/1.73 m(2)) and steroids (1 mg/d/kg body weight) led to rapid remission, with eGFR of 107 mL/min/1.73 m(2) [1.78 mL/s/1.73 m(2)] and a prolonged decrease in CFH antibody titer after 15 months (1,300 AU). Patient 3, a 16-month-old boy, was treated with oral steroids (1 mg/d/kg body weight), 2 PEs, and 2 cyclophosphamide pulses (0.5 g/1.73 m(2)), resulting in a stable decrease in CFH antibody titer to 276 AU. Kidney function quickly normalized (eGFR, 110 mL/min/1.73 m(2) [1.83 mL/s/1.73 m(2)]) and has remained normal after 14 months. All 3 patients show a homozygous deletion mutation of the CFHR1 and CFHR3 genes. Cyclophosphamide pulses with PE may lead to a prolonged decrease in CFH antibody titers and a favorable outcome of atypical hemolytic uremic syndrome and kidney function.

Schimke immunoosseous dysplasia: suggestions of genetic diversity.

Schimke immunoosseous dysplasia (SIOD), which is characterized by prominent spondyloepiphyseal dysplasia, T-cell deficiency, and focal segmental glomerulosclerosis, is a panethnic autosomal recessive multisystem disorder with variable expressivity. Biallelic mutations in switch/sucrose nonfermenting (swi/snf) related, matrix-associated, actin-dependent regulator of chromatin, subfamily a-like 1 (SMARCAL1) are the only identified cause of SIOD. However, among 72 patients from different families, we identified only 38 patients with biallelic mutations in the coding exons and splice junctions of the SMARCAL1 gene. This observation, the variable expressivity, and poor genotype-phenotype correlation led us to test several hypotheses including modifying haplotypes, oligogenic inheritance, or locus heterogeneity in SIOD. Haplotypes associated with the two more common mutations, R820H and E848X, did not correlate with phenotype. Also, contrary to monoallelic SMARCAL1 coding mutations indicating oligogenic inheritance, we found that all these patients did not express RNA and/or protein from the other allele and thus have biallelic SMARCAL1 mutations. We hypothesize therefore that the variable expressivity among patients with biallelic SMARCAL1 mutations arises from environmental, genetic, or epigenetic modifiers. Among patients without detectable SMARCAL1 coding mutations, our analyses of cell lines from four of these patients showed that they expressed normal levels of SMARCAL1 mRNA and protein. This is the first evidence for nonallelic heterogeneity in SIOD. From analysis of the postmortem histopathology from two patients and the clinical data from most patients, we propose the existence of endophenotypes of SIOD.