Successful long-term outcome of pediatric liver-kidney transplantation: a single-center study.

INTRODUCTION: Liver-kidney transplantation is a rare procedure in children, with just ten to 30 cases performed annually worldwide. The main indications are autosomal recessive polycystic liver-kidney disease and primary hyperoxaluria. This study aimed to report outcomes of liver-kidney transplantation in a cohort of pediatric patients. METHODS: We retrospectively analyzed all pediatric liver-kidney transplantations performed in our center between September 2000 and August 2015. Patient data were obtained by reviewing inpatient and outpatient medical records and our transplant database. RESULTS: A total of 14 liver-kidney transplants were performed during the study period, with a median patient age and weight at transplant of 144.4 months (131.0-147.7) and 27.3 kg (12.0-45.1), respectively. The indications for liver-kidney transplants were autosomal recessive polycystic liver-kidney disease (8/14), primary hyperoxaluria -1 (5/14), and idiopathic portal hypertension with end-stage renal disease (1/14). Median time on waiting list was 8.5 months (5.7-17.3). All but two liver-kidney transplants were performed simultaneously. Patients with primary hyperoxaluria-1 tended to present a delayed recovery of renal function compared with patients transplanted for other indications (62.5 vs 6.5 days, respectively, P 0.076). Patients with liver-kidney transplants tended to present a lower risk of acute kidney rejection than patients transplanted with an isolated kidney transplant (7.2% vs 32.7%, respectively; P < 0.07). Patient and graft survival at 1, 3, and 5 years were 100%, 91.7%, 91.7%, and 91.7%, 83.3%, 83.3%, respectively. No other grafts were lost. CONCLUSION: Long-term results of liver-kidney transplants in children are encouraging, being comparable with those obtained in isolated liver transplantation.

Long-term eculizumab improves clinical outcomes in atypical hemolytic uremic syndrome.

BACKGROUND: Atypical hemolytic uremic syndrome (aHUS) is a rare genetic disorder caused by chronic uncontrolled complement activation. CASE-DIAGNOSIS/TREATMENT: We present a 4-year-old girl with aHUS who had multiple severe clinical manifestations of thrombotic microangiopathy (TMA) including acute kidney injury, dilated cardiomyopathy, and cardiorespiratory arrest. She was managed with intensive plasma exchange and hemodialysis, which could not halt the progression of TMA. The initial single dose of eculizumab only temporarily improved the clinical symptoms of TMA. Sustained improvement of renal, hematological, and cardiac values were only achieved upon institution of chronic treatment with eculizumab. During long-term treatment with eculizumab (>2.5 years), she has had no further clinical manifestations of TMA, and required neither plasma exchange nor hemodialysis. CONCLUSION: Chronic eculizumab treatment was associated with control of complement-mediated TMA and sustained long-term improvement in renal and cardiac function.

Genetic diagnosis of X-linked dominant Hypophosphatemic Rickets in a cohort study: tubular reabsorption of phosphate and 1,25(OH)2D serum levels are associated with PHEX mutation type.

BACKGROUND: Genetic Hypophosphatemic Rickets (HR) is a group of diseases characterized by renal phosphate wasting with inappropriately low or normal 1,25-dihydroxyvitamin D3 (1,25(OH)2D) serum levels. The most common form of HR is X-linked dominant HR (XLHR) which is caused by inactivating mutations in the PHEX gene. The purpose of this study was to perform genetic diagnosis in a cohort of patients with clinical diagnosis of HR, to perform genotype-phenotype correlations of those patients and to compare our data with other HR cohort studies. METHODS: Forty three affected individuals from 36 non related families were analyzed. For the genetic analysis, the PHEX gene was sequenced in all of the patients and in 13 cases the study was complemented by mRNA sequencing and Multiple Ligation Probe Assay. For the genotype-phenotype correlation study, the clinical and biochemical phenotype of the patients was compared with the type of mutation, which was grouped into clearly deleterious or likely causative, using the Mann-Whitney and Fisher's exact test. RESULTS: Mutations in the PHEX gene were identified in all the patients thus confirming an XLHR. Thirty four different mutations were found distributed throughout the gene with higher density at the 3' end. The majority of the mutations were novel (69.4%), most of them resulted in a truncated PHEX protein (83.3%) and were family specific (88.9%). Tubular reabsorption of phosphate (TRP) and 1,25(OH)2D serum levels were significantly lower in patients carrying clearly deleterious mutations than in patients carrying likely causative ones (61.39 ± 19.76 vs. 80.14 ± 8.80%, p = 0.028 and 40.93 ± 30.73 vs. 78.46 ± 36.27 pg/ml, p = 0.013). CONCLUSIONS: PHEX gene mutations were found in all the HR cases analyzed, which was in contrast with other cohort studies. Patients with clearly deleterious PHEX mutations had lower TRP and 1,25(OH)2D levels suggesting that the PHEX type of mutation might predict the XLHR phenotype severity.

Very low-molecular-mass fragments of albumin in the plasma of patients with focal segmental glomerulosclerosis.

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 > or =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.

TRPC6 mutational analysis in a large cohort of patients with focal segmental glomerulosclerosis.

BACKGROUND: Mutations in the TRPC6 gene have been reported in six families with adult-onset (17-57 years) autosomal dominant focal segmental glomerulosclerosis (FSGS). Electrophysiology studies confirmed augmented calcium influx only in three of these six TRPC6 mutations. To date, the role of TRPC6 in childhood and adulthood non-familial forms is unknown. METHODS: TRPC6 mutation analysis was performed by direct sequencing in 130 Spanish patients from 115 unrelated families with FSGS. An in silico scoring matrix was developed to evaluate the pathogenicity of amino acid substitutions, by using the bio-physical and bio-chemical differences between wild-type and mutant amino acid, the evolutionary conservation of the amino acid residue in orthologues, homologues and defined domains, with the addition of contextual information. RESULTS: Three new missense substitutions were identified in two clinically non-familial cases and in one familial case. The analysis by means of this scoring system allowed us to classify these variants as likely pathogenic mutations. One of them was detected in a female patient with unusual clinical features: mesangial proliferative FSGS in childhood (7 years) and partial response to immunosupressive therapy (CsA + MMF). Asymptomatic carriers of this likely mutation were found within her family. CONCLUSIONS: We describe for the first time TRPC6 mutations in children and adults with non-familial FSGS. It seems that TRPC6 is a gene with a very variable penetrance that may contribute to glomerular diseases in a multi-hit setting.

Long-term outcome in a case series of Denys-Drash syndrome.

BACKGROUND: Denys-Drash syndrome (DDS) is a rare disease caused by mutations in exons 8 and 9 of the WT1 gene. It is characterized by the association of early onset steroid-resistant nephrotic syndrome (SRNS), Wilms' tumour and, in some patients, intersex disorders, with increasing risk of gonadoblastoma. There are few published data concerning the long-term outcome of patients with DDS. The aim of this study was to report our experience. METHODS: Data were collected from five children (three boys) with confirmed DDS diagnosed from 1996 to 2017. The mean follow-up of these patients was 16 years. RESULTS: The patients presented with SRNS and diffuse mesangial sclerosis at renal biopsy. All patients were hypertensive and progressed to end-stage kidney disease, initiating dialysis at a mean age of 28 months. Three patients developed Wilms' tumour 9 months after the SRNS was identified, which was treated by nephrectomy and chemotherapy. All five patients received kidney transplantation. SRNS did not recur after transplantation in any of the patients and graft survival was similar to that of other kidney transplant recipients in our programme. All three boys had ambiguous genitalia and cryptorchidism but a confirmed male karyotype (46, XY). One girl presented with gonadal agenesis, whereas the other one had normal female ovarian tissue and external genitalia. Both girls had a female karyotype (46, XX). Gonadoblastoma was not observed at any case. CONCLUSIONS: Early DDS recognition in patients with SRNS is crucial due to its low prevalence, the specific treatment approach required and early detection of Wilms' tumour. Few data are available regarding long-term outcomes.

Mesangial C4d Deposits in Early IgA Nephropathy.

BACKGROUND AND OBJECTIVES: The prognostic value of mesangial C4d deposits in IgA nephropathy has been analyzed in patients with reduced GFR but has not been analyzed in those with normal kidney function. The main objective of the study was to analyze the prognostic value of C4d deposits and association with response to treatment in patients with IgA nephropathy and normal GFR. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: This retrospective cohort study included 190 patients with idiopathic IgA nephropathy diagnosed by kidney biopsy between 1988 and 2005. The patients had GFR≥80 ml/min per 1.73 m2 at the time of diagnosis, and they had a paraffin-embedded kidney biopsy with eight glomeruli available. RESULTS: In total, 170 (89%) and 20 (11%) patients were >18 and <18 years old, respectively; median (interquartile range) follow-up was 15 (12-22) years. Mesangial C4d deposit prevalence was 20% (38 of 190). At diagnosis, C4d-positive versus -negative patients had higher protein-to-creatinine ratio (median [interquartile range]: 1.94 g/g [0.9-3.1] versus 1.45 g/g [0.9-2.2]; P=0.04). During follow-up, C4d-positive patients showed a higher number of nephritic flares (median [range]: 1.4 [0-5] versus 0.9 [0-2]; P=0.04), had a higher protein-to-creatinine ratio (median [interquartile range]: 1.32 g/g [0.7-1.7] versus 0.89 g/g [0.1-1.3]; P<0.01), were more prone to receive repeated treatment with corticosteroids (45% versus 24%; P<0.01), and showed a larger reduction in eGFR (-1.6 versus -0.8 ml/min per 1.73 m2 per year; P=0.04). Furthermore, the presence of mesangial C4d deposits was an independent predictor of long-term kidney survival. CONCLUSIONS: C4d deposits may be one of the earliest poor prognostic variables available for patients with idiopathic IgA nephropathy and normal kidney function at the time of diagnosis. However, Cd4 deposits alone are not associated with the response to angiotensin blockers or corticosteroid treatment.

Treatment of Post-transplant Lymphocele in Children.

OBJECTIVE: To review our single-center experience in managing posttransplant lymphoceles in pediatric kidney recipients. Lymphoceles are well-known complications after pediatric kidney transplantation (KT). However, there is no standard treatment for lymphoceles, and the literature lacks consensus on which is the most appropriate approach. MATERIALS AND METHODS: We reviewed our retrospective institutional database for recipients of pediatric KT performed between January 2000 and December 2015 who developed lymphoceles. RESULTS: Out of the 176 patients who underwent KT, lymphoceles occurred in 9 (5.1%) patients. The mean age of recipients in this group was 12.8 years (standard deviation [SD] 4.8) (r: 1-17) and the mean body weight was 43.1 kg (SD 18.8) (r: 9.5-69). Mean lymphocele onset was 32.2 days (SD 23.4) (r: 11-85) post transplantation. Six patients presented with increased serum creatinine from the baseline, whereas 3 patients remained asymptomatic. Ultrasound was the primary diagnostic procedure in all patients. Lymphoceles resolved spontaneously in asymptomatic patients (n = 3), and thus these patients were not further treated. All symptomatic patients (n = 6) were treated: 2 underwent percutaneous catheter drainage and 4 underwent transcatheter sclerotherapy (TS). The main sclerosing agent used was povidone-iodine. In 3 patients, TS with povidone-iodine failed, and they underwent additional procedures: 2 underwent TS with polidocanol and 1 underwent open drainage. There was no graft loss in any of the patients, and no recurrence was documented during a follow-up period of mean 30.3 months (SD 15.6) (r: 7-57). CONCLUSION: There is no gold-standard treatment for lymphoceles in children, and reports in the literature on the topic are scarce. Percutaneous catheter drainage with or without TS is safe and effective, although it can lengthen hospitalization and increase morbidity.

An update for atypical haemolytic uraemic syndrome: diagnosis and treatment. A consensus document.

Haemolytic uraemic syndrome (HUS) is a clinical entity defined as the triad of nonimmune haemolytic anaemia, thrombocytopenia, and acute renal failure, in which the underlying lesions are mediated by systemic thrombotic microangiopathy (TMA). Different causes can induce the TMA process that characterizes HUS. In this document we consider atypical HUS (aHUS) a sub-type of HUS in which the TMA phenomena are the consequence of the endotelial damage in the microvasculature of the kidneys and other organs due to a disregulation of the activity of the complement system. In recent years, a variety of aHUs-related mutations have been identified in genes of the the complement system, which can explain approximately 60% of the aHUS cases, and a number of mutations and polymorphisms have been functionally characterized. These findings have stablished that aHUS is a consequence of the insufficient regulation of the activiation of the complement on cell surfaces, leading to endotelial damage mediated by C5 and the complement terminal pathway. Eculizumab is a monoclonal antibody that inhibits the activation of C5 and blocks the generation of the pro-inflammatory molecule C5a and the formation of the cell membrane attack complex. In prospective studies in patients with aHUS, the use of Eculizumab has shown a fast and sustained interruption of the TMA process and it has been associated with significative long-term improvements in renal function, the interruption of plasma therapy and important reductions in the need of dialysis. According to the existing literature and the accumulated clinical experience, the Spanish aHUS Group published a consensus document with recommendations for the treatment of aHUs (Nefrologia 2013;33[1]:27-45). In the current online version of this document, we update the aetiological classification of TMAs, the pathophysiology of aHUS, its differential diagnosis and its therapeutic management.

An update for atypical haemolytic uraemic syndrome: diagnosis and treatment. A consensus document.

Haemolytic uraemic syndrome (HUS) is a clinical entity defined as the triad of nonimmune haemolytic anaemia, thrombocytopenia, and acute renal failure, in which the underlying lesions are mediated by systemic thrombotic microangiopathy (TMA). Atypical HUS (aHUS) is a sub-type of HUS in which the TMA phenomena are the consequence of decreased regulation of the alternative complement pathway on cell surfaces due to a genetic cause. aHUS is an extremely rare disease that, despite the administration of standard treatment with plasma therapy, often progresses to terminal chronic renal failure with a high associated rate of mortality. In recent years, research has established the key role that the complement system plays in the induction of endothelial damage in patients with aHUS, through the characterisation of multiple mutations and polymorphisms in the genes that code for certain complement factors. Eculizumab is a monoclonal antibody that inhibits the terminal fraction of the complement protein, blocking the formation of a cell membrane attack complex. In prospective studies in patients with aHUS, administering eculizumab produces a rapid and sustained interruption in the TMA process, with significant improvements in long-term renal function and an important decrease in the need for dialysis or plasma therapy. In this document, we review and bring up to date the important aspects of this disease, with special emphasis on how recent advancements in diagnostic and therapeutic processes can modify the treatment of patients with aHUS.

A new point mutation in the COL4A5 gene described in a Spanish family with X-linked Alport syndrome.

BACKGROUND/AIM: Alport syndrome is a hereditary glomerulonephritis, X-linked in 85% of the cases. This form is associated with mutations in the COL4A5 gene which encodes the alpha5 chain of type IV collagen. We have performed the mutational analysis of the COL4A5 gene in a Spanish family with X-linked Alport syndrome. METHODS: We have analyzed three polymorphic markers close to the gene to confirm the X chromosome linkage. By means of the PCR technique, we have screened the 51 exons of the gene. RESULTS: The segregation of the alleles from the analyzed markers was in agreement with the X linkage. Direct sequencing of PCR-amplified products has shown a CCT-to-CTT change in exon 25, resulting in substitution of a proline for a leucine at position 619 of the polypeptide chain (nucleotide 2058). CONCLUSIONS: Although proline is considered a nonconserved amino acid, it is essential, upon hydroxylation, in the maintenance of a stable alpha chain triple-helix collagen. Furthermore, the change cosegregates with the disease in all affected members of the family, not being present in 80 control chromosomes. This represents a new mutation in the COL4A5 gene found in the Spanish population.