Karine Brochard

Phenotype–genotype correlation in antenatal and neonatal variants of Bartter syndrome

BACKGROUND Ante/neonatal Bartter syndrome (BS) is a hereditary salt-losing tubulopathy due to mutations in genes encoding proteins involved in NaCl reabsorption in the thick ascending limb of Henles loop. Our aim was to study the frequency, clinical characteristics and outcome of each genetic subtype. METHODS Charts of 42 children with mutations in KCNJ1 (n = 19), SLC12A1 (n = 13) CLCNKB (n = 6) or BSND (n = 4) were retrospectively analysed. The median follow-up was 8.3 [0.4-18.0] years. RESULTS We describe 24 new mutations: 10 in KCNJ1, 11 in SLC12A1 and 3 in CLCNKB. The onset of polyhydramnios, birth term, height and weight were similar for all groups; three patients had no history of polyhydramnios or premature birth and had CLCNKB mutations according to a less severe renal sodium wasting. Contrasting with these data, patients with CLCNKB had the lowest potassium (P = 0.006 versus KCNJ1 and P = 0.034 versus SLC12A1) and chloride plasma concentrations (P = 0.039 versus KCNJ1 and P = 0.024 versus SLC12A1) and the highest bicarbonataemia (P = 0.026 versus KCNJ1 and P = 0.014 versus SLC12A1). Deafness at diagnosis was constant in patients with BSND mutations; transient neonatal hyperkalaemia was present in two-thirds of the children with KCNJ1 mutations. Nephrocalcinosis was constant in KCNJ1 and SLC12A1 but not in BSND and CLCNKB patients. In most cases, water/electrolyte supplementation + indomethacin led to catch-up growth. Three patients developed chronic renal failure: one with KCNJ1 mutations during the second decade of age and two with CLCNKB and BSND mutations and without nephrocalcinosis during the first year of life. CONCLUSIONS We confirmed in a large cohort of ante/ neonatal BS that deafness, transient hyperkalaemia and severe hypokalaemic hypochloraemic alkalosis orientate molecular investigations to BSND, KCNJ1 and CLCNKB genes, respectively. Chronic renal failure is a rare event, associated in this cohort with three genotypes and not always associated with nephrocalcinosis.

Population Pharmacokinetics and Pharmacogenetics of Mycophenolic Acid Following Administration of Mycophenolate Mofetil in De Novo Pediatric Renal‐Transplant Patients

The objective was to develop a population pharmacokinetic‐pharmacogenetic model of mycophenolic acid following administration of mycophenolate mofetil (MMF) in de novo pediatric renal‐transplant patients and identify factors that explain variability. The pharmacokinetic samples were collected from 89 de novo pediatric renal‐transplant patients treated with MMF and studied during the first 60 postoperative days. All patients were genotyped for UGT1A8–A9, UGT2B7, and ABCC2. Population pharmacokinetic analysis was performed with the NONMEM and was validated using bootstrap visual predictive check. The pharmacokinetic data were best described by a 2‐compartment model with Erlang distribution to describe the absorption phase. The covariate analysis identified body weight as an individual factor influencing central volume of distribution and concomitant immunosuppressive medication and identified body weight and UGT2B7 802C>T genotype as individual factors influencing apparent oral clearance (CL/F) of MMF. CL/F in cyclosporine‐MMF‐treated patients was 33% higher than in tacrolimus‐MMF‐treated patients. The CL/F was significantly lower in patients with UGT2B7 802 C/C genotype compared with patients with UGT2B7 802 C/T and 802T/T genotypes, and this effect was independent of concomitant immunosuppressive medication or body weight. The population pharmacokinetic‐pharmacogenetic model of mycophenolic acid was validated. Body weight, concomitant medication, and UGT2B7 genotype contribute significantly to the interindividual variability of MMF disposition in pediatric renal‐transplant patients.

Population pharmacokinetics and Bayesian estimator of mycophenolic acid in children with idiopathic nephrotic syndrome

AIMS To develop a population pharmacokinetic model for mycophenolic acid (MPA) in children with idiopathic nephrotic syndrome (INS) treated with mycophenolate mofetil (MMF), identify covariates that explain variability and determine the Bayesian estimator of the area under the concentration-time curve over 12 h (AUC(0-12)). METHODS The pharmacokinetic model of MMF was described from 23 patients aged 7.4 +/- 3.9 years (range 2.9-14.9) using nonlinear mixed-effects modelling (NONMEM) software. A two-compartment model with lag-time and first-order absorption and elimination was developed. The final model was validated using visual predictive check. Bayesian estimator was validated using circular permutation method. RESULTS The population pharmacokinetic parameters were apparent oral clearance 9.7 l h(-1), apparent central volume of distribution 22.3 l, apparent peripheral volume of distribution 250 l, inter-compartment clearance 18.8 l h(-1), absorption rate constant 5.16 h(-1), lag time 0.215 h. The covariate analysis identified body weight and serum albumin as individual factors influencing the apparent oral clearance. Accurate Bayesian estimation of AUC(0-12) was obtained using the combination of three MPA concentrations measured just before (T(0)), 1 and 4 h (T(1) and T(4)) after drug intake with a small error of 0.298 microg h(-1) ml(-1) between estimated and reference AUC(0-12). CONCLUSIONS The population pharmacokinetic model of MPA was developed in children with INS. A three-point (T(0), T(1) and T(4)h) Bayesian estimator of AUC(0-12) was developed and might be used to investigate the relation between MPA pharmacokinetic and pharmacodynamics in children with INS and determine if there is any indication to monitor MPA exposure in order to improve patient outcome based on individual AUC-controlled MMF dosing.

Clonal Cytophagic Histiocytic Panniculitis in Children May Be Cured by Cyclosporine A

Cytophagic histiocytic panniculitis (CHP) is a rare panniculitis in childhood, associated either with nonmalignant conditions or with subcutaneous panniculitis-like T-cell lymphoma (SPTCL), and often also associated with macrophage activation syndrome (MAS). Discriminating between these 2 conditions is therapeutically important because nonmalignant CHP often improves under cyclosporine and prednisone, whereas most cases of SPLT may be best treated with more aggressive therapy. We report the cases of a 6-month-old boy and a 16-month-old girl who, after viral infection, developed multiple infiltrating skin nodules on the limbs and face, associated with MAS. Histopathologic findings for skin biopsy specimens revealed CHP associated with heavily cellular lobular panniculitis. Hemophagocytosis and immunohistochemical staining features were consistent with typical characteristics of in situ MAS in adipose tissue: the lymphocytes were mostly TCD8+ cells with an activated phenotype (human leukocyte antigen (HLA) -DR+) and expressed interferon-γ; CD68+ macrophages expressed tumor necrosis factor-α and interleukin-6. A monoclonal rearrangement of the T-cell receptor γ gene was present in skin tissue but not in peripheral blood or bone marrow lymphocytes. Cyclosporine A treatment resulted in the complete remission of cutaneous and systemic manifestations in both patients for 66 and 29 months, respectively. This report suggests that the diagnosis of a reactive T-cell lymphoproliferation should be the treatment of choice in young children with severe CHP, even if there is a SPTCL-like aspect with an in situ T-cell clonality. It also suggests that CSA is the optimal treatment of this condition and postulates the possible pathologic process underlying this efficacy.

Severe global inflammatory involvement of ocular segments and optic disc swelling in a 12-year-old girl with Kawasaki disease

Purpose Pediatric Kawasaki ocular involvement is dominated by bulbar conjunctival injection and mild, self-limited anterior uveitis. Posterior segment involvement is rare. Methods/Results Case report. Despite early efficient treatment including aspirin and intravenous immunoglobulins, a 12-year-old girl developed a severe bilateral global inflammatory ocular involvement including punctuated keratitis, retrodescemetic precipitates, anterior uveitis, vitritis, and bilateral optic disc swelling with papillitis. This is the first description of severe bilateral global inflammatory involvement of the eyes in Kawasaki disease (KD). Usually subclinical and self-limited, eye involvement in KD can lead to severe visual impairment. Conclusions Inflammation of both anterior and posterior segments does not seem to respond to KD-specific treatment and could justify a specific ophthalmologic therapeutic approach.

Mycophenolic Acid Pharmacokinetics and Relapse in Children with Steroid–Dependent Idiopathic Nephrotic Syndrome

BACKGROUND AND OBJECTIVES Therapeutic drug monitoring of mycophenolic acid can improve clinical outcome in organ transplantation and lupus, but data are scarce in idiopathic nephrotic syndrome. The aim of our study was to investigate whether mycophenolic acid pharmacokinetics are associated with disease control in children receiving mycophenolate mofetil for the treatment of steroid-dependent nephrotic syndrome. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS This was a retrospective multicenter study including 95 children with steroid-dependent nephrotic syndrome treated with mycophenolate mofetil with or without steroids. Area under the concentration-time curve of mycophenolic acid was determined in all children on the basis of sampling times at 20, 60, and 180 minutes postdose, using Bayesian estimation. The association between a threshold value of the area under the concentration-time curve of mycophenolic acid and the relapse rate was assessed using a negative binomial model. RESULTS In total, 140 areas under the concentration-time curve of mycophenolic acid were analyzed. The findings indicate individual dose adaptation in 53 patients (38%) to achieve an area under the concentration-time curve target of 30-60 mg·h/L. In a multivariable negative binomial model including sex, age at disease onset, time to start of mycophenolate mofetil, previous immunomodulatory treatment, and concomitant prednisone dose, a level of area under the concentration-time curve of mycophenolic acid >45 mg·h/L was significantly associated with a lower relapse rate (rate ratio, 0.65; 95% confidence interval, 0.46 to 0.89; P=0.01). CONCLUSIONS Therapeutic drug monitoring leading to individualized dosing may improve the efficacy of mycophenolate mofetil in steroid-dependent nephrotic syndrome. Additional prospective studies are warranted to determine the optimal target for area under the concentration-time curve of mycophenolic acid in this population.

Steroid-responsive nephrotic syndrome in a child with juvenile idiopathic arthritis

Renal disease is rare in children with juvenile idiopathic arthritis, although a number of associated nephropathies have been described, including mesangial glomerulonephritis. We report the presence of mesangial glomerulonephritis, revealed by a nephrotic syndrome, in a paediatric patient with juvenile idiopathic arthritis. Short-term steroid treatment induced a rapid remission of the nephrotic syndrome, but the presence of anti-nuclear antibodies, 1:320 in a homogeneous pattern, irregular deposits of C1q in a renal biopsy, and a mother with episodes of cutaneous lupus suggested an uncertain renal evolution for this infant.

Value of biomarkers for predicting immunoglobulin A vasculitis nephritis outcome in an adult prospective cohort

Background Henoch-Schönlein purpura, more recently renamed immunoglobulin A vasculitis (IgAV), is a systemic vasculitis characterized by IgA deposits. The current markers used to assess IgAV inaccurately evaluate the risk of nephritis occurrence and its long-term outcomes. The current study assessed biomarkers of nephritis outcomes. Methods This French multicentre prospective study enrolled 85 adult patients at the time of disease onset. Patients were assessed for clinical and biological parameters and re-examined after 1 year. Immunoglobulins, cytokines, IgA glycosylation, IgA complexes and neutrophil gelatinase-associated lipocalin (NGAL) concentrations were assessed in blood and urine. Results We identified 60 patients with IgAV-related nephritis (IgAV-N) and 25 patients without nephritis (IgAV-woN). At the time of inclusion (Day 1), the serum levels of galactose-deficient IgA1 (Gd-IgA1) and urinary concentrations of IgA, IgG, IgM, NGAL, interleukin (IL)-1β, IL-6, IL-8, IL-10, IgA-IgG and IgA-sCD89 complexes were higher in the IgAV-N patients than in the IgAV-woN patients (P < 0.005 for all comparisons). After follow-up (1 year), 22 patients showed a poor outcome. Among the tested markers, urine IgA at disease onset adequately reclassified the risk of poor outcome over conventional clinical factors, including estimated glomerular filtration rate, proteinuria and age (continuous net reclassification improvement = 0.72, P = 0.001; integrated discrimination improvement = 0.13, P = 0.009) in IgAV patients. Conclusions Taken together, these results showed that serum Gd-IgA1 and urinary IgA, IgG, IgM, NGAL, IL-1β, IL-6, IL-8, IL-10, IgA-IgG and IgA-sCD89 complexes were associated with nephritis in IgAV patients. Urinary IgA level may improve patient risk stratification for poor outcome.

Révélation atypique d’un syndrome de Churg et Strauss chez l’enfant

We report the case of a 13-year-old boy who had been treated since the age of 6 for moderate asthma. Except asthma, his past medical history was uneventful. The patient was referred for the sudden onset of bilateral leg edemas with peripheral purpuric lesions. Blood tests showed increased blood eosinophilia (9000/mm(3)) with no fever. The antineutrophil cytoplasmic antibodies (ANCA) were negative. The skin biopsy showed extensive ischemic subcutaneous necrosis related to necrotizing vasculitis. The general secondary symptoms occurred with multiorgan involvement (pulmonary infiltrates, peripheral neuropathy, gastrointestinal tract symptoms, and arthralgia). Genital infiltration was also noted. The childs general health was preserved. Neither cardiac nor renal involvement were found. The patient showed favorable clinical progression after oral prednisone therapy.

Clinical characteristics, management and outcomes in patients with juvenile dermatomyositis requiring admission in pediatric intensive care unit

Results 11/116 DMJ (9.3%) (8 girls and 3 boys, median age at diagnosis : 9.0± 3.1 years) were admitted in ICU for digestive involvement (2 with digestive perforation after pulse corticosteroids) (4 patients), bradycardia (1 patient), cardiac arrest (1 patient), hypoxemic pneumonia (1 patient), PRES syndrome due to cyclosporine (1 patient), thrombotic microangiopathy (TMA) (2 patients) and anaphylactic shock due to Rituximab (1 patient). The incidence of some clinical and biological manifestations differed from severe patients to patients with mild JDM: hyponatremia (9), hypoalbuminemia (9), generalized edema (6), anemia (hemoglobin value <8 g/dL) (8), abdominal pain (7), thrombocytopenia (platelet count : 100-150 x 10/L )(7). The patients were treated by corticosteroids (11, comprising 5 with pulse), intravenous immunoglobulins (7), plasmapheresis (7), Rituximab (4) and cyclophosphamide (2). One patient died in ICU from pneumocystosis ; 5 are currently in complete remission and 5 in partial remission with a mean follow-up duration of 4,7 years.