Background
Rituximab (RTX) is efficient in steroid-dependent nephrotic syndrome (SDNS) in pediatric and adult patients. The aim of this study is to describe hypogammaglobulinemia as a side effect of ...RTX treatment.
Methods
All pediatric patients (< 18 years old) of four French pediatric nephrology centers who received RTX for SDNS between 2010 and 2015 have been included. Clinical and biological data have been analyzed retrospectively before, during, and after RTX treatment. Hypogammaglobulinemia was defined as an IgG level < − 2 standard deviations for patient age.
Results
A total of 107 pediatric patients have been included, 65.9% were boys, median age at nephrotic syndrome diagnosis was 3.1 interquartile range IQ 2.24–5.45 years and age at RTX introduction was 11.7 IQ 8.6–14.2 years. Twenty-one patients had hypogammaglobulinemia before the initiation of RTX. Of the patients, 25/86 had at least one hypogammaglobulinemia during B cell depletion or after B cell recovery while IgG levels at initiation were normal with a persisting hypogammaglobulinemia for 13 patients 1 year after B cell recovery. Patients who developed hypogammaglobulinemia were younger at RTX initiation with a median age of 8.2 years IQ 6.3–12.4. Among all the 46 patients with hypogammaglobulinemia during follow-up, 13 had a concomitant infection.
Conclusions
Hypogammaglobulinemia is a frequent complication of RTX treatment in younger children treated for SDNS. The use of RTX in children has to be carefully evaluated and their clinical and biological follow-up should be adapted to the age-dependent risk profile for hypogammaglobulinemia.
Abstract
N
6
-threonyl-carbamoylation of adenosine 37 of ANN-type tRNAs (t
6
A) is a universal modification essential for translational accuracy and efficiency. The t
6
A pathway uses two ...sequentially acting enzymes, YRDC and OSGEP, the latter being a subunit of the multiprotein KEOPS complex. We recently identified mutations in genes encoding four out of the five KEOPS subunits in children with Galloway-Mowat syndrome (GAMOS), a clinically heterogeneous autosomal recessive disease characterized by early-onset steroid-resistant nephrotic syndrome and microcephaly. Here we show that mutations in
YRDC
cause an extremely severe form of GAMOS whereas mutations in
GON7
, encoding the fifth KEOPS subunit, lead to a milder form of the disease. The crystal structure of the GON7/LAGE3/OSGEP subcomplex shows that the intrinsically disordered GON7 protein becomes partially structured upon binding to LAGE3. The structure and cellular characterization of GON7 suggest its involvement in the cellular stability and quaternary arrangement of the KEOPS complex.
Fabry disease (FD), a rare X‐linked disease, can be treated with bi‐monthly infusion of enzyme replacement therapy (ERT) to replace deficient α‐galactosidase A (AGAL‐A). ERT reduces symptoms, ...improves quality of life (QoL), and improves clinical signs and biochemical markers. ERT initiation in childhood could slow or stop progressive organ damage. Preventative treatment of FD from childhood is thought to avoid organ damage in later life, prompting a French expert working group to collaborate and produce recommendations for treating and monitoring children with FD. Organ involvement should be assessed by age 5 for asymptomatic boys (age 12‐15 for asymptomatic girls), and immediately for children diagnosed via symptoms. The renal, cardiac, nervous and gastrointestinal systems should be assessed, as well as bone, skin, eyes, hearing, and QoL. The plasma biomarker globotriaosylsphingosine is also useful. ERT should be considered for symptomatic boys and girls with neuropathic pain, pathological albuminuria (≥3 mg/mmol creatinine), severe GI involvement and abdominal pain or cardiac involvement. ERT should be considered for asymptomatic boys from the age of 7. Organ involvement should be treated as needed. Early diagnosis and management of FD represents a promising strategy to reduce organ damage, morbidity and premature mortality in adulthood.
HNF1B-related disease is an emerging condition characterized by an autosomal-dominant inheritance, a 50% rate of de novo mutations, and a highly variable phenotype (renal involvement, maturity-onset ...diabetes of the young type 5, pancreatic hypoplasia, and urogenital tract and liver test abnormalities). Given the current lack of pathognomonic characteristics and the wide overlap with other conditions, a genetic test is the diagnostic gold standard. However, pre-genetic screening is mandatory because genetic testing has substantial costs. Our aim was to develop a HNF1B score, based on clinical, imaging, and biological variables, as a pivotal tool for rational genetic testing. A score was created using a weighted combination of the most discriminative characteristics based on the frequency and specificity in published series. The HNF1B score is calculated upon 17 items including antenatal discovery, family history, and organ involvement (kidney, pancreas, liver, and genital tract). The performance of the score was assessed by a ROC curve analysis in a 433-individual cohort containing 56 HNF1B cases. The HNF1B score efficiently and significantly discriminated between mutated and nonmutated cases (AUC 0.78). The optimal cutoff threshold for the negative predictive value to rule out HNF1B mutations in a suspected individual was 8 (sensitivity 98.2%, specificity 41.1%, and negative predictive value over 99%). Thus, the HNF1B score is a simple and accurate tool to provide a more rational approach to select patients for HNF1B screening.
Production of amniotic fluid (AF) is view as predominately driven by excretion of fetal urine (FU). However, the origin of AF peptides, often considered as potential biomarkers of developmental ...diseases, has never been investigated. Here, we evaluated the FU origin of AF peptides and if the AF peptide content can be used as a surrogate of FU. The abundance of endogenous peptides was analyzed by capillary electrophoresis coupled to mass spectrometry in 216 AF and 64 FU samples. A total of 2668 and 3257 peptides was found in AF and FU respectively. The AF peptidome largely overlapped with the FU peptidome, ranging from 54% in the second pregnancy trimester to 65% in the third trimester. Examination of a subset of 16 paired AF and FU samples revealed that 67 peptides displayed a significant positively correlated abundance in AF and FU, strongly suggesting that their presence in AF was directly associated to FU excretion. As proof-of-concept we showed that measuring the AF abundance of these 67 peptides of FU origin allowed prediction of postnatal renal survival in fetuses with posterior urethral valves. These results demonstrate that the AF peptidome can be considered as a good surrogate of the FU peptidome.
Hepatocyte nuclear factor 1beta (HNF1beta) is a transcription factor that is critical for the development of kidney and pancreas. In humans, mutations in HNF1B lead to congenital anomalies of the ...kidney and urinary tract, pancreas atrophy, and maturity-onset diabetes of the young type 5 and genital malformations.
We report HNF1B screening in a cohort of 377 unrelated cases with various kidney phenotypes (hyperechogenic kidneys with size not more than +3 SD, multicystic kidney disease, renal agenesis, renal hypoplasia, cystic dysplasia, or hyperuricemic tubulointerstitial nephropathy not associated with UMOD mutation).
We found a heterozygous mutation in 75 (19.9%) index cases, consisting of a deletion of the whole gene in 42, deletion of one exon in one, and small mutations in 32. Eighteen mutations were novel. De novo mutations accounted for 66% of deletions and 40% of small mutations. In patients who carried HNF1B mutation and for whom we were able to study prenatal ultrasonography (56 probands), isolated hyperechogenic kidneys with normal or slightly enhanced size were the more frequent (34 of 56) phenotype before birth. Various other prenatal renal phenotypes were associated with HNF1B mutations, at a lesser frequency. Diabetes developed in four probands. Hyperuricemia and hypomagnesemia, although not systematically investigated, were frequently associated.
This large series showed that the severity of the renal disease associated with HNF1B mutations was extremely variable (from prenatal renal failure to normal renal function in adulthood) and was not correlated with the genotype.
Owing to its availability, ease of collection, and correlation with pathophysiology of diseases, urine is an attractive source for clinical proteomics. However, many proteomic studies have had only ...limited clinical impact, due to factors such as modest numbers of subjects, absence of disease controls, small numbers of defined biomarkers, and diversity of analytical platforms. Therefore, it is difficult to merge biomarkers from different studies into a broadly applicable human urinary proteome database. Ideally, the methodology for defining the biomarkers should combine a reasonable analysis time with high resolution, thereby enabling the profiling of adequate samples and recognition of sufficient features to yield robust diagnostic panels. CE‐MS, which was used to analyze urine samples from healthy subjects and patients with various diseases, is a suitable approach for this task. The database of these datasets compiled from the urinary peptides enables the diagnosis, classification, and monitoring of a wide range of diseases. CE‐MS exhibits excellent performance for biomarker discovery and allows subsequent biomarker sequencing independent of the separation platform. This approach may elucidate the pathogenesis of many diseases, and better define especially renal and urological disorders at the molecular level.
Cases reports and small series of patients with C3 glomerulopathy have reported variable efficacy of eculizumab.
Case series of C3 glomerulopathy.
Pediatric and adult patients with C3 glomerulopathy ...treated with eculizumab between 2010 and 2016 were identified through the C3 glomerulopathy French registry database, and a questionnaire was sent to participating French pediatric and adult nephrology centers, as well as one pediatric referral center in Québec, Canada.
Global or partial clinical renal response.
Evolution of serum creatinine and proteinuria values.
26 patients (13 children/adolescents) were included. 22 (85%) patients had received steroids, plasma exchange, or immunosuppressive therapy before eculizumab, and 3 of them had rapid progression of their kidney disease despite treatment. At the initiation of eculizumab therapy, 11 (42%) patients had chronic kidney disease, 7 (27%) had rapidly progressive disease, and 3 (12%) required dialysis. After eculizumab treatment (median duration, 14 months), 6 (23%) patients had a global clinical response; 6 (23%), a partial clinical response; and 14 (54%), no response. Compared with those who had a partial clinical or no response, patients who had a global clinical response had lower estimated glomerular filtration rates, a more rapidly progressive course, and more extracapillary proliferation on kidney biopsy. Age, extent of renal fibrosis, frequency of nephrotic syndrome, low serum C3 and C3 nephritic factor and elevated soluble C5b-9 concentrations, or complement gene variants did not differ between responders and nonresponders.
Retrospective design without a control group, relatively small number of cases, inclusion of pediatric and adult cases.
Eculizumab appears to be a potential treatment for patients with crescentic rapidly progressive C3 glomerulopathy. Its benefit in patients with non–rapidly progressing forms seems to be limited.
Background
Mycophenolic acid (MPA), the active compound of mycophenolate mofetil (MMF), is widely used in lupus nephritis treatment. Therapeutic drug monitoring of adults suggests that area under the ...concentration-time curve (AUC) of MPA (MPA-AUC) is associated with clinical outcomes, but childhood data are scarce.
Methods
Retrospective study of 27 children with biopsy-proven lupus nephritis treated with MMF between 2008 and 2016. In 25 children, MPA-AUC was performed within 6 months after kidney biopsy and MMF initiation. Treatment response at 6 months was defined as normal or improved GFR by 25% compared with baseline, 50% reduction of proteinuria to < 0.5 g/day or 50 mg/mmol, and no hematuria.
Results
A total of 62 MPA-AUC were analyzed in 27 patients. Overall median was 44 mg h/L (interquartile range IQR 33–54). Individual dose adaptation was required in 32 cases (52%) to achieve target AUC of 30–60 mg h/L. At 6 months, 14/25 patients were defined as responders (56%, median MPA-AUC 49 mg h/L (40–59)) and 11/25 as non-responders (44%, 29 mg h/L (24–38)). Patients with MPA-AUC levels > 45, 30–45, and < 30 mg h/L had 6-month response rates of 89% (8/9), 60% (6/10), and 0% (0/6), respectively. In a logistic regression model adjusted for age, sex, lupus nephritis classification, and time since MMF initiation, an MPA-AUC > 45 mg h/L was significantly associated with therapeutic response (OR 3.6, 95% CI 2.4–9.5,
p
= 0.03).
Conclusions
Therapeutic drug monitoring leading to individualized dosing may improve efficacy of MMF. MPA-AUC > 45 mg h/L is associated with better response rate and may be considered as a target value in pediatric lupus nephritis.
Nephronophthisis (NPH) comprises a group of rare disorders accounting for up to 10% of end-stage kidney disease (ESKD) in children. Prediction of kidney prognosis poses a major challenge. We assessed ...differences in kidney survival, impact of variant type, and the association of clinical characteristics with declining kidney function.
Data was obtained from 3 independent sources, namely the network for early onset cystic kidney diseases clinical registry (n = 105), an online survey sent out to the European Reference Network for Rare Kidney Diseases (n = 60), and a literature search (n = 218).
A total of 383 individuals were available for analysis: 116 NPHP1, 101 NPHP3, 81 NPHP4 and 85 NPHP11/TMEM67 patients. Kidney survival differed between the 4 cohorts with a highly variable median age at onset of ESKD as follows: NPHP3, 4.0 years (interquartile range 0.3–12.0); NPHP1, 13.5 years (interquartile range 10.5–16.5); NPHP4, 16.0 years (interquartile range 11.0–25.0); and NPHP11/TMEM67, 19.0 years (interquartile range 8.7–28.0). Kidney survival was significantly associated with the underlying variant type for NPHP1, NPHP3, and NPHP4. Multivariate analysis for the NPHP1 cohort revealed growth retardation (hazard ratio 3.5) and angiotensin-converting enzyme inhibitor (ACEI) treatment (hazard ratio 2.8) as 2 independent factors associated with an earlier onset of ESKD, whereas arterial hypertension was linked to an accelerated glomerular filtration rate (GFR) decline.
The presented data will enable clinicians to better estimate kidney prognosis of distinct patients with NPH and thereby allow personalized counseling.
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