Background
Primary hypophosphatemic syndromes are a heterogeneous group of rare diseases. In recent years, fibroblast growth factor 23 (FGF23) has been postulated as a useful tool for differential ...diagnosis of hypophosphatemic rickets characterized by impaired renal phosphate reabsorption. This study aimed to investigate the utility of FGF23 to discriminate between X-linked hypophosphatemic rickets (XLH), an FGF23-driven disease, from other causes of renal phosphate wasting such as Fanconi syndrome (FS), a generalized dysfunction of the proximal tubule unrelated to FGF23.
Methods
Circulating levels of intact FGF23 (iFGF23) were measured in nine children with XLH receiving conventional therapy (six girls, mean ± SD age 10.8 ± 6.7 years) and nine children with secondary FS (four girls, mean ± SD age 9.9 ± 5.2 years), using an automated chemiluminescent immunoassay. Phosphate, calcium, creatinine, estimated glomerular filtration rate (eGFR), intact parathormone (iPTH), and urinary parameters were evaluated simultaneously. Maximum renal tubular threshold for phosphate reabsorption (TmP/GFR) was also estimated.
Results
Plasma iFGF23 concentrations in patients with XLH were significantly higher than those in the SF group: 146.2 ± 69.2 ng/L vs. 29.5 ± 15.0 ng/L (
p
< 0.001). Remarkably, we did not observe an overlap between XLH and FS patients. Significant hypophosphatemia (2.55 ± 0.50 mg/dL) and secondary hyperparathyroidism (iPTH 109.4 ± 58.1 ng/mL) were present in XLH patients, while FS patients showed modest hypophosphatemia (3.97 ± 0.68 mg/dL), higher TmP/GFR compared with XLH, lower eGFR and hypercalciuria.
Conclusions
This study supports the value of measuring FGF23 levels as a useful tool to exclude XLH in patients with increased phosphate wasting of kidney origin.
Graphical Abstract
X-linked hypophosphatemia (XLH) is a hereditary rare disease caused by loss-of-function mutations in PHEX gene leading tohypophosphatemia and high renal loss of phosphate. Rickets and growth ...retardation are the major manifestations of XLH in children, but there is a broad phenotypic variability. Few publications have reported large series of patients. Current data on the clinical spectrum of the disease, the correlation with the underlying gene mutations, and the long-term outcome of patients on conventional treatment are needed, particularly because of the recent availability of new specific medications to treat XLH.
The RenalTube database was used to retrospectively analyze 48 Spanish patients (15 men) from 39 different families, ranging from 3 months to 8 years and 2 months of age at the time of diagnosis (median age of 2.0 years), and with XLH confirmed by genetic analysis. Bone deformities, radiological signs of active rickets and growth retardation were the most common findings at diagnosis. Mean (± SEM) height was - 1.89 ± 0.19 SDS and 55% (22/40) of patients had height SDS below-2. All cases had hypophosphatemia, serum phosphate being - 2.81 ± 0.11 SDS. Clinical manifestations and severity of the disease were similar in both genders. No genotype-phenotype correlation was found. Conventional treatment did not attenuate growth retardation after a median follow up of 7.42 years (IQR = 11.26; n = 26 patients) and failed to normalize serum concentrations of phosphate. Eleven patients had mild hyperparathyroidism and 8 patients nephrocalcinosis.
This study shows that growth retardation and rickets were the most prevalent clinical manifestations at diagnosis in a large series of Spanish pediatric patients with XLH confirmed by mutations in the PHEX gene. Traditional treatment with phosphate and vitamin D supplements did not improve height or corrected hypophosphatemia and was associated with a risk of hyperparathyroidism and nephrocalcinosis. The severity of the disease was similar in males and females.
Type III Bartter syndrome (BS) is an autosomal recessive renal tubule disorder caused by loss-of-function mutations in the CLCNKB gene, which encodes the chloride channel protein ClC-Kb. In this ...study, we carried out a complete clinical and genetic characterization in a cohort of 30 patients, one of the largest series described. By comparing with other published populations, and considering that 80% of our patients presented the p.Ala204Thr Spanish founder mutation presumably associated with a common phenotype, we aimed to test the hypothesis that allelic differences could explain the wide phenotypic variability observed in patients with type III BS.
Clinical data were retrieved from the referral centers. The exon regions and flanking intronic sequences of the CLCNKB gene were screened for mutations by polymerase chain reaction (PCR) followed by direct Sanger sequencing. Presence of gross deletions or duplications in the region was checked for by MLPA and QMPSF analyses.
Polyuria, polydipsia and dehydration were the main common symptoms. Metabolic alkalosis and hypokalemia of renal origin were detected in all patients at diagnosis. Calciuria levels were variable: hypercalciuria was detected in 31% of patients, while 23% had hypocalciuria. Nephrocalcinosis was diagnosed in 20% of the cohort. Two novel CLCNKB mutations were identified: a small homozygous deletion (c.753delG) in one patient and a small deletion (c.1026delC) in another. The latter was present in compound heterozygosis with the already previously described p.Glu442Gly mutation. No phenotypic association was obtained regarding the genotype.
A poor correlation was found between a specific type of mutation in the CLCNKB gene and type III BS phenotype. Importantly, two CLCNKB mutations not previously described were found in our cohort.
Background Primary focal segmental glomerulosclerosis (FSGS) is a glomerular disease that frequently does not respond to treatment and progresses to kidney failure. FSGS can be of either genetic ...origin, caused by mutations in slit diaphragm proteins, such as podocin, or idiopathic origin of unknown cause. Study Design Case series. Setting & Participants Children with FSGS (aged 3-18 years); 15 with idiopathic and 11 with genetic forms of FSGS. Predictor Genetic versus idiopathic forms. Outcomes & Measurements Differentially expressed proteins in the plasma proteome, detected using 2-dimensional electrophoresis and identified using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, Western blot, and liquid chromatography electron spray ionization tandem mass spectrometry for fragmentation and identification of the peptides. Results We found 3 very low-molecular-mass (9.2, 6.9, and 4.7 kDa; isoelectric point, 5.7) spots that were present in pooled samples from patients with genetic FSGS, but missing in patients with idiopathic FSGS and healthy individuals. Spots were identified using mass spectrometry as fragments of albumin, 2 of them apparently containing peptides from both C- and N-terminal parts of the whole protein. Proteomic analyses were carried out on all genetic patients individually; of these, 10 of 11 patients had ≥1 albumin fragment detected in the pool. We did not find an evident relationship between type of mutation or clinical status of patients and albumin fragments observed. Limitations Very low-molecular-weight albumin fragments also can be produced by other diseases. Conclusions We describe for the first time the presence of very low-molecular-mass albumin fragments in plasma of patients with FSGS with podocyte protein mutations that are absent in patients with idiopathic FSGS or healthy individuals. Additional studies are necessary to determine whether these fragments could be potential biomarkers to distinguish between genetic and idiopathic forms of FSGS.
There are currently no models for the transition of patients with metabolic bone diseases (MBDs) from paediatric to adult care. The aim of this project was to analyse information on the experience of ...physicians in the transition of these patients in Spain, and to draw up consensus recommendations with the specialists involved in their treatment and follow-up. The project was carried out by a group of experts in MBDs and included a systematic review of the literature for the identification of critical points in the transition process. This was used to develop a questionnaire with a total of 48 questions that would determine the degree of consensus on: (a) the rationale for a transition programme and the optimal time for the patient to start the transition process; (b) transition models and plans; (c) the information that should be specified in the transition plan; and (d) the documentation to be created and the training required. Recommendations and a practical algorithm were developed using the findings. The project was endorsed by eight scientific societies. A total of 86 physicians from 53 Spanish hospitals participated. Consensus was reached on 45 of the 48 statements. There was no agreement that the age of 12 years was an appropriate and feasible point at which to initiate the transition in patients with MBD, nor that a gradual transition model could reasonably be implemented in their own hospital. According to the participants, the main barriers for successful transition in Spain today are lack of resources and lack of coordination between paediatric and adult units. The TEAM Project gives an overview of the transition of paediatric MBD patients to adult care in Spain and provides practical recommendations for its implementation.
Objective
To find out if cardiovascular alterations are present in pediatric patients with X-linked hypophosphatemia (XLH).
Study design
Multicentre prospective clinical study on pediatric patients ...included in the RenalTube database (
www.renaltube.com
) with genetically confirmed diagnosis of XLH by mutations in the
PHEX
gene. The study’s protocol consisted of biochemical work-up, 24-h ambulatory blood pressure monitoring (ABPM), carotid ultrasonography, and echocardiogram. All patients were on chronic treatment with phosphate supplements and 1-hydroxy vitamin D metabolites.
Results
Twenty-four patients (17 females, from 1 to 17 years of age) were studied. Serum concentrations (X ± SD) of phosphate and intact parathyroid hormone were 2.66 ± 0.60 mg/dl and 58.3 ± 26.8 pg/ml, respectively. Serum fibroblast growth factor 23 (FGF23) concentration was 278.18 ± 294.45 pg/ml (normal < 60 pg/ml). Abnormally high carotid intima media thickness was found in one patient, who was obese and hypertensive as revealed by ABPM, which disclosed arterial hypertension in two other patients.
Z
scores for echocardiographic interventricular septum end diastole and left ventricular posterior wall end diastole were + 0.77 ± 0.77 and + 0.94 ± 0.86, respectively. Left ventricular mass index (LVMI) was 44.93 ± 19.18 g/m
2.7
, and four patients, in addition to the obese one, had values greater than 51 g/m
2.7
, indicative of left ventricular hypertrophy. There was no correlation between these echocardiographic parameters and serum FGF23 concentrations.
Conclusions
XLH pediatric patients receiving conventional treatment have echocardiographic measurements of ventricular mass within normal reference values, but above the mean, and 18% have LVMI suggestive of left ventricular hypertrophy without correlation with serum FGF23 concentrations. This might indicate an increased risk of cardiovascular involvement in XLH.
Atypical hemolytic uremic syndrome is a form of thrombotic microangiopathy caused by dysregulation of the alternative complement pathway. There is evidence showing complement activation in other ...thrombotic microangiopathies. The aim of this study was to evaluate complement activation in different thrombotic microangiopathies and to monitor treatment response.
Complement activation was assessed by exposing endothelial cells to sera or activated-patient plasma-citrated plasma mixed with a control sera pool (1:1)-to analyze C5b-9 deposits by immunofluorescence. Patients with atypical hemolytic uremic syndrome (
=34) at different stages of the disease, HELLP syndrome (a pregnancy complication characterized by hemolysis, elevated liver enzymes, and low platelet count) or severe preeclampsia (
=10), and malignant hypertension (
=5) were included.
Acute phase atypical hemolytic uremic syndrome-activated plasma induced an increased C5b-9 deposition on endothelial cells. Standard and lower doses of eculizumab inhibited C5b-9 deposition in all patients with atypical hemolytic uremic syndrome, except in two who showed partial remission and clinical relapse. Significant fibrin formation was observed together with C5b-9 deposition. Results obtained using activated-plasma samples were more marked and reproducible than those obtained with sera. C5b-9 deposition was also increased with samples from patients with HELLP (all cases) and preeclampsia (90%) at disease onset. This increase was sustained in those with HELLP after 40 days, and levels normalized in patients with both HELLP and preeclampsia after 6-9 months. Complement activation in those with malignant hypertension was at control levels.
The proposed methodology identifies complement overactivation in patients with atypical hemolytic uremic syndrome at acute phase and in other diseases such as HELLP syndrome and preeclampsia. Moreover, it is sensitive enough to individually assess the efficiency of the C5 inhibition treatment.
Primary distal renal tubular acidosis (DRTA) is a rare disease caused by loss-of-function mutations in at least three genes (ATP6V0A4, ATP6V1B1, and SLC4A1) involved in urinary distal acidification. ...The next-generation sequencing (NGS) technique facilitates the search for mutations in DRTA patients and helps to characterize the genetic and clinical spectrum of the disease.
Ten DRTA patients were studied. They had normal serum anion gap (AG), metabolic acidosis with simultaneous positive urinary AG, and inability to maximally acidify the urine. The exons of the three genes were sequenced in two pools by ultrasequencing. Putative mutations were confirmed by corresponding Sanger sequencing of each exon.
We found 13 mutations in nine patients. ATP6V0A4: Intron16+2insA; p.R807Q; p.Q276fs; p.P395fs; Intron7-2T>C. ATP6V1B1: p.I386fs; p.R394Q. SLC4A1: p.V245M; p.R589C; p.R589H; p.G609A. One case was a compound heterozygous with a known mutation in ATP6V1B1 (p.G609R) and a pathogenic variation at SLC4A1 (p.E508K). One patient was negative for mutations.
This study evidences that NGS is labor and cost effective for the analysis of DRTA genes. Our results show for the first time SLC4A1 gene mutations in Spanish patients and disclose that compound heterozygosity at two different genes can be responsible for DRTA.
Background
Urinary tract infection (UTI) is one of the most common bacterial infections in childhood and is associated with long-term complications. We aimed to assess the effect of adjuvant ...dexamethasone treatment on reducing kidney scarring after acute pyelonephritis (APN) in children.
Methods
Multicenter, prospective, double-blind, placebo-controlled, randomized clinical trial (RCT) where children from 1 month to 14 years of age with proven APN were randomly assigned to receive a 3-day course of either an intravenous corticosteroid (dexamethasone 0.30 mg per kg/day) twice daily or placebo. The late technetium 99 m-dimercaptosuric acid scintigraphy (> 6 months after acute episode) was performed to assess kidney scar persistence. Kidney scarring risk factors (vesicoureteral reflux, kidney congenital anomalies, or urinary tract dilatation) were also assessed.
Results
Ninety-one participants completed the follow-up and were finally included (dexamethasone
n
= 49 and placebo
n
= 42). Both groups had similar baseline characteristics. Twenty participants showed persistent kidney scarring after > 6 months of follow-up without differences in incidence between groups (22% and 21% in the dexamethasone and placebo groups,
p
= 0.907). Renal damage severity in the early DMSA (β = 0.648,
p
= 0.023) and procalcitonin values (β = 0.065
p
= 0.027) significantly modulated scar development. Vesicoureteral reflux grade showed a trend towards significance (β = 0.545,
p
= 0.054), but dexamethasone treatment showed no effect.
Conclusion
Dexamethasone showed no effect on reducing the risk of scar formation in children with APN. Hence, there is no evidence for an adjuvant corticosteroid treatment recommendation in children with APN. However, the study was limited by not achieving the predicted sample size and the expected scar formation.
Trial registration
Clinicaltrials.gov, NCT02034851. Registered in January 14, 2014.
Graphical abstract
“A higher resolution version of the Graphical abstract is available as Supplementary information.”
Introducción: La enfermedad pulmonar intersticial difusa (EPID) describe un amplio grupo de trastornos con inflamación y fibrosis pulmonar. La asbestosis y la silicosis son las principales causas por ...exposición laboral. El objetivo de este trabajo fue estimar la proporción de casos de posible origen laboral y describir la exposición, situación clínica y laboral. Método: Estudio longitudinal retrospectivo de los casos de EPID, en el período 2017-2022 en el Hospital Universitario de Navarra. Se completó la información con entrevista a los casos de posible origen laboral. Resultados: De un total de 1067 casos de EPID, 56 tuvieron un posible origen laboral, 5,2% (3,9-6,6 IC 95%) 36 (64,3%) correspondieron a asbestosis, 15 (26,8%) a silicosis y 5 (8,9%) a neumoconiosis no especificada. Las actividades más frecuentes en silicosis fueron “corte-tallado de piedra” y para asbestosis ”fabricación productos hierro”. La media de edad de los casos de asbestosis fue superior a los de silicosis (78,2 vs. 67,3 años), así como su afectación clínica. Cinco casos (8,9%) habían sido reconocidos como enfermedad profesional Conclusiones: La implementación de una herramienta informática en historia clínica ha hecho posible estimar la magnitud y valorar la evolución de las EPID laborales atendidas en el servicio nacional de salud. Las actividades económicas reflejan la estructura económica de riesgo de la región. Sin embargo, existe una falta de su reconocimiento como enfermedad profesional y suponen una carga de enfermedad respiratoria evitable.
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