Use of T1 mapping in cardiac MRI for the follow-up of Fabry disease in a pediatric population

Background

Fabry disease (FD) is a rare X-linked lysosomal disorder caused by pathogenic variants in the alpha-galactosidase-A gene (GLA). Life threatening complications in adulthood include chronic kidney failure, strokes and the cardiac involvement which is the leading cause of mortality. Usually, it presents with hypertrophic cardiomyopathy, together with arrhythmia and conduction abnormalities. An early indicator is decreased T1 value on cardiac magnetic resonance (CMR). Enzyme replacement therapy (ERT) is effective on some extra-cardiac symptoms but its effect on cardiac lesions depends on the level of initial myocardial lesions. CMR is routinely used to monitor cardiac involvement in FD due to its capacity for tissular characterization. However, there is a lack of data on the pediatric population to understand how to integrate CMR into early therapeutic decisions.

Method

Monocentric longitudinal study carried out at Montpellier University Hospital from 2016 to 2022. All pediatric patients with FD were evaluated over time with clinical, biological, and cardiac imaging (CMR, echocardiography).

Results

Out of the six patients included, (3 males), five were treated with ERT during the study. Low T1 values were observed in 4 patients. The normalization of T1 values was observed after 4 years of ERT in 3 patients.

Conclusion

Due to the lack of strong clinical and biological markers of FD in pediatric patients, initiation and follow-up of ERT efficacy remain challenging. CMR with T1-mapping, a noninvasive method, could play a role in the evaluation of early cardiac impairment in young patients at diagnosis and during follow-up with or without ERT.

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.

Long-term outcome of children treated with rituximab for idiopathic nephrotic syndrome

BACKGROUND

Rituximab (RTX) has recently showed promising results in the treatment of steroid-dependent idiopathic nephrotic syndrome (SDNS).

METHODS

This was a retrospective multicenter study of 18 children treated with RTX for SDNS, with a mean follow-up of 3.2 years. RTX was introduced because of side effects or relapses during therapy with immunosuppressive agents. The children received one to four infusions of RTX during the first course of treatment, and subsequent infusions were given due to CD19-cell recovery (CD19 >1 %; 54 % of children) or relapse (41 %), as well as systematically (5 %).

RESULTS

Treatment with RTX maintained sustained remission without relapse in 22 % of patients and increased the duration of remission in all other patients. The time between two successive relapses was 9 months in the absence of re-treatment and 24.5 months when infusions were performed at the time of CD19-cell recovery. At the last follow-up, 44.5 % of patients were free of oral drug therapy. Of those still receiving oral drugs, all doses had been decreased. No serious adverse events occurred.

CONCLUSION

The results of this retrospective study confirm the efficacy and very good safety of RTX in the treatment of SDNS. The optimal therapeutic protocol seems to be a repeated single infusion at the time of CD19-cell recovery.

[Hemolytic uremic syndrome with severe neurological involvement: how should it be managed?]

INTRODUCTION

The management of diarrhea-associated hemolytic and uremic syndrome (D(+) HUS) with severe acute neurological involvement continues to be debated. We report on 2 cases and discuss the treatment. CASE REPORT 1: A 2.5-year-old girl presented with generalized seizures during gastroenteritis. Blood tests revealed features of HUS and a pyramidal syndrome was found on physical examination. Brain MRI, 24h after admission, showed lesions in the periventricular and subcortical area. She was started on peritoneal dialysis (PD) and daily plasma exchanges (PE) for 10 days. Her neurological condition improved quickly as well as the findings of the second brain MRI performed after PE. One year later she had no apparent neurological or renal sequelae. CASE REPORT 2: A 2.5-year-old boy presented with generalized seizures during gastroenteritis for 3 days, leading to a diagnosis of HUS. He also had a severe pyramidal syndrome with spastic tetraparesis and aphasia. Brain MRI, 48 h after admission, revealed severe bilateral and symmetric lesions involving the thalami, internal and external capsules, lenticular nuclei, and brainstem. He was started on PD and daily PE for 10 days. Brain MRI performed after PE was unchanged. Clinically, his neurological condition improved slowly with regression of spastic tetraparesis and progressive recovery of motor skills. Nine months later, his renal function is normal but he is still having intensive physiotherapy.

DISCUSSION

Both children have received similar management including 10 PEs started within 48 h after the diagnosis of D(+) HUS with severe neurological involvement, but their neurological outcome appeared to be significantly different. There is no clear proof in the literature concerning the effects of PE in such patients, even when performed very early. Eculizumab, an antibody that inhibits complement factor 5a and the formation of the membrane attack complex, has recently been used in such cases and seems to provide a more specific therapeutic action. Control studies are needed to specify its use in this disease.

Favorable outcome in a case of Mycoplasma pneumoniae-associated crescentic glomerulonephritis

Mycoplasma pneumoniae-associated nephritis has been reported in children with various pathological findings. It nevertheless remains an uncommon disease and, within this clinical context, endo-and extracapillary glomerulonephritis in a child has never been described. We report here a case of a 3-year-old girl diagnosed with severe crescentic glomerulonephritis associated with M. pneumoniae infection who presented with nephrotic syndrome and impaired renal function. The serum C3 complement level was initially low but returned to normal after 1 month. Two courses of three methylprednisolone pulses were administered in association with plasmapheresis and, secondarily, mycophenolate mophetil. This treatment regimen led to disease remission and a favorable renal outcome at the 6-month follow-up. However, the treatment guidelines in this situation remain debatable.

[Association of severe bronchial disease (bronchial casts, bronchiectasis) and partial abnormal pulmonary venous drainage in 2 children with Turner's syndrome]

The prevalence of cardiovascular malformation is high in Turner's syndrome. We report two cases of partial anomalous pulmonary venous drainage associated with a severe bronchial disease.

CASE REPORTS

Case 1: a 5-year-old girl with monosomy X presented with acute respiratory failure. The chest X-ray showed an atelectasis of the left lower lobe. The patient improved following bronchoscopic removal of a bronchial cast. During hospitalization, an anomalous pulmonary venous drainage of the right lung was discovered. In spite of complete surgical repair of the cardiac malformation, several episodes of respiratory failure occurred several years after the operation. Case 2: a 9-year-old girl with monosomy X and coarctation of the aorta underwent pre-operative cardiac catheterization. She had a history of bronchiectasis, leading to a lobectomy. Her respiratory condition improved following surgery. A partial anomalous pulmonary venous return was discovered during the cardiac angiography. The coarctation was repaired surgically. The correction of the left-to-right shunt was not necessary.

CONCLUSION

The partial anomalous pulmonary venous return is frequently reported in Turner's syndrome. The possible respiratory disease associated with this cardiac malformation is usually described as a consequence of the increase in pulmonary blood flow. Our two cases did not match this hypothesis.

[Hematuria revealing primary hyperparathyroidism in a child]

BACKGROUND

Hematuria rarely reveals primary hyperparathyroidism in the child.

CASE REPORT

A 10-year-old boy presented with gross hematuria and urolithiasis. Biological findings showed hypercalcemia and hypercalciuria. Initially, parathormone plasma levels remained within normal range, but raised after a few months and at that time, ultrasound scan examination showed a parathyroid adenoma. Nevertheless, two surgical explorations were necessary to cure hypercalcemia and hyperparathyroidism. Histological aspects of parathyroid adenoma were not found on pathological examination.

CONCLUSION

Symptomatic hypercalciuria may be the first symptom revealing primary hyperparathyroidism in children. Surgical treatment remains difficult in such a case.