Human C-terminal CUBN variants associate with chronic proteinuria and normal renal function.

BACKGROUNDProteinuria is considered an unfavorable clinical condition that accelerates renal and cardiovascular disease. However, it is not clear whether all forms of proteinuria are damaging. Mutations in CUBN cause Imerslund-Gräsbeck syndrome (IGS), which is characterized by intestinal malabsorption of vitamin B12 and in some cases proteinuria. CUBN encodes for cubilin, an intestinal and proximal tubular uptake receptor containing 27 CUB domains for ligand binding.METHODSWe used next-generation sequencing for renal disease genes to genotype cohorts of patients with suspected hereditary renal disease and chronic proteinuria. CUBN variants were analyzed using bioinformatics, structural modeling, and epidemiological methods.RESULTSWe identified 39 patients, in whom biallelic pathogenic variants in the CUBN gene were associated with chronic isolated proteinuria and early childhood onset. Since the proteinuria in these patients had a high proportion of albuminuria, glomerular diseases such as steroid-resistant nephrotic syndrome or Alport syndrome were often the primary clinical diagnosis, motivating renal biopsies and the use of proteinuria-lowering treatments. However, renal function was normal in all cases. By contrast, we did not found any biallelic CUBN variants in proteinuric patients with reduced renal function or focal segmental glomerulosclerosis. Unlike the more N-terminal IGS mutations, 37 of the 41 proteinuria-associated CUBN variants led to modifications or truncations after the vitamin B12-binding domain. Finally, we show that 4 C-terminal CUBN variants are associated with albuminuria and slightly increased GFR in meta-analyses of large population-based cohorts.CONCLUSIONCollectively, our data suggest an important role for the C-terminal half of cubilin in renal albumin reabsorption. Albuminuria due to reduced cubilin function could be an unexpectedly common benign condition in humans that may not require any proteinuria-lowering treatment or renal biopsy.FUNDINGATIP-Avenir program, Fondation Bettencourt-Schueller (Liliane Bettencourt Chair of Developmental Biology), Agence Nationale de la Recherche (ANR) Investissements d'avenir program (ANR-10-IAHU-01) and NEPHROFLY (ANR-14-ACHN-0013, to MS), Steno Collaborative Grant 2018 (NNF18OC0052457, to TSA and MS), Heisenberg Professorship of the German Research Foundation (KO 3598/5-1, to AK), Deutsche Forschungsgemeinschaft (DFG) Collaborative Research Centre (SFB) KIDGEM 1140 (project 246781735, to CB), and Federal Ministry of Education and Research (BMB) (01GM1515C, to CB).

Long-term successful liver-kidney transplantation in a child with atypical hemolytic uremic syndrome caused by homozygous factor H deficiency.

BACKGROUND: Rational options for the treatment of end-stage renal disease (ESRD) due to atypical hemolytic uremic syndrome (aHUS) in children are still open to discussion. In the case of human complement factor H (CFH) deficiency, the choice is either kidney transplantation in combination with eculizumab, a humanized anti-C5 monoclonal antibody, or a combined liver-kidney transplantation. CASE-DIAGNOSIS/TREATMENT: A child with a homozygous CFH deficiency underwent a successful liver-kidney transplantation. CFH levels normalized within days. After 6 years of follow-up, the graft function (Cockroft clearance 100 ml min-1 1.73 m-2) and the liver functions were normal. RESULTS AND CONCLUSIONS: The results of this long-term follow-up confirm that combined liver-kidney transplantation remains a reasonable option in patients with ESRD due to aHUS when an identified genetic abnormality of the C3 convertase regulator synthesized in the liver has been identified.

[Urinary tract infection in children]. / Infections urinaires de l'enfant.

Urinary tract infection in children. The care of a child suspected of urinary infection (UI) goes through 4 stages. The diagnosis of UI is based on the presence of bacteriuria > 105 / mL, the collection of urine through a bas is unreliable and source of false positives. Localization diagnosis (acute pyelonephritis or cystitis) is based on clinical and biological signs (leukocytosis and inflammation). Etiological diagnosis is based on renal ultrasonography looking for obstructive uropathy, stones and bladder dysfunction; the search for a vesico-ureteral reflux with retrograd cystography is not systematic at first infection. The treatment of acute pyelonephritis is initiated usually intravenously for a period of 3 or 4 days. Oral antibiotics is then possible.

Infections urinaires de l'enfant. La prise en charge d'un enfant suspect d'infection urinaire passe par quatre étapes. Le diagnostic positif d'infection urinaire est posé en présence d'une bactériurie supérieure à 105 germes/mL ; le recueil des urines sur poche est peu fiable et source de faux positifs. Le diagnostic de localisation (pyélonéphrite aiguë ou cystite) repose sur des signes cliniques et biologiques (hyperleucocytose et syndrome inflammatoire). Le diagnostic causal repose sur l'interrogatoire et l'échographie rénale à la recherche d'une uropathie obstructive, d'une lithiase et d'un dysfonctionnement vésical. La recherche d'un reflux vésico-urétéral par cystographie rétrograde dès la première pyélonéphrite aiguë n'est pas systématique. Le traitement de la pyélonéphrite aiguë est initié le plus souvent par voie intraveineuse pour une durée de 2 à 3 jours ; le relais est ensuite pris par un traitement oral.

Escherichia coli virulence patterns may help to predict vesicoureteral reflux in paediatric urinary tract infections.

AIM: Ultrasound and biological tools are used to predict high-grade vesicoureteral reflux, but other markers are needed to better select patients who need voiding cystography. Our aim was to determine whether studying Escherichia coli virulence factors would help to predict vesicoureteral reflux in patients with their first acute pyelonephritis. METHODS: We included children presenting with E. coli-related acute pyelonephritis or cystitis. Vesicoureteral reflux was assessed by voiding cystography. Virulence factors were identified by multiplex polymerase chain reaction. Statistical analysis was performed using logistic regression and the mean c-statistic test. RESULTS: We included 198 patients: 30 with cystitis and 168 with acute pyelonephritis, including 46 with vesicoureteral reflux. High-grade reflux was associated with acute pyelonephritis caused by the E. coli lacking virulence factors papGII (82% versus 47%, p < 0.001) or papC (85% versus 53%, p < 0.001) or belonging to phylogenetic group A or B1. When we added genetic data (lack of papGII, fyuA and phylogenetic groups) to classical predictors of vesicoureteral reflux (ultrasound examination, gender, age), the ability to predict high-grade reflux increased, with the c-statistic rising from 0.88 to 0.93. CONCLUSION: Bacterial virulence factors and clinical factors helped to predict high-grade reflux and may help to avoid unnecessary voiding cystographies.

Long-term results of combined liver-kidney transplantation for primary hyperoxaluria type 1: the French experience.

Primary hyperoxaluria type 1 (PH1) is a hepatic metabolic defect leading to end-stage renal failure. The posttransplant recurrence of kidney disease can suggest a need for combined liver-kidney transplantation (LKT). However, the risk of LKT is theoretically far higher than the risk of kidney-alone transplantation (KAT). An unselected consecutive series of 54 patients with PH1 was analyzed according to the type of transplantation initially performed between May 1979 and June 2010 at 10 French centers. The duration of dialysis, extrarenal lesions, age, and follow-up were similar between the groups. Postoperative morbidity and mortality did not differ between the groups, and 10-year patient survival rates were similar for the LKT (n = 33) and KAT groups (n = 21; 78% versus 70%). Kidney graft survival at 10 years was better after LKT (87% versus 13%, P < .001) . Four patients (12.1%) lost their first kidney graft in the LKT group, whereas 19 (90%) did in the KAT group (P < .001). The recurrence of oxalosis occurred in 11 renal grafts (52%) in the KAT group but in none in the LKT group (P < .001). End-stage renal failure resulting from rejection was also higher in the KAT group (19% versus 9%, P < 0.0001). A second kidney transplant was performed for 15 patients (71%) in the KAT group versus 4 patients (12%) in the LKT group (P < 0.001). In conclusion, LKT for PH1 provides better kidney graft survival, less rejection, and similar long-term patient survival and is not associated with an increased short-term mortality risk. LKT must be the first-line treatment for PH1 patients with end-stage renal disease.

Acute metabolic acidosis in a GLUT2-deficient patient with Fanconi-Bickel syndrome: new pathophysiology insights.

Fanconi-Bickel syndrome is a rare autosomal-recessive disorder caused by mutations in the SLC2A2 gene coding for the glucose transporter protein 2 (GLUT2). Major manifestations include hepatomegaly, glucose intolerance, post-prandial hypoglycaemia and renal disease that usually presents as proximal tubular acidosis associated with proximal tubule dysfunction (renal Fanconi syndrome). We report a patient harbouring a homozygous mutation of SLC2A2 who presented a dramatic exacerbation of metabolic acidosis in the context of a viral infection, owing to both ketosis and major urinary bicarbonate loss. The kidney biopsy revealed nuclear and cytoplasmic accumulation of glycogen in proximal tubule cells, a lack of expression of GLUT2, and major defects of key proteins of the proximal tubule such as megalin, cubilin and the B2 subunit of H(+)-ATPase. These profound alterations of the transport systems most likely contributed to proximal tubule alterations and profound bicarbonate loss.

Adenine phosphoribosyltransferase deficiency.

Complete adenine phosphoribosyltransferase (APRT) deficiency is a rare inherited metabolic disorder that leads to the formation and hyperexcretion of 2,8-dihydroxyadenine (DHA) into urine. The low solubility of DHA results in precipitation of this compound and the formation of urinary crystals and stones. The disease can present as recurrent urolithiasis or nephropathy secondary to crystal precipitation into renal parenchyma (DHA nephropathy). The diagnostic tools available-including stone analysis, crystalluria, and APRT activity measurement-make the diagnosis easy to confirm when APRT deficiency is suspected. However, the disease can present at any age, and the variability of symptoms can present a diagnostic challenge to many physicians. The early recognition and treatment of APRT deficiency are of crucial importance for preventing irreversible loss of renal function, which still occurs in a non-negligible proportion of cases. This review summarizes the genetic and metabolic mechanisms underlying stone formation and renal disease, along with the diagnosis and management of APRT deficiency.

Adenine phosphoribosyltransferase deficiency in children.

Adenine phosphoribosyltransferase (APRT) deficiency is a rare autosomal recessive disorder characterized by 2,8-dihydroxyadenine (2,8-DHA) crystalluria that can cause nephrolithiasis and chronic kidney disease. The aim of our study was to assess the clinical presentation, diagnosis, and outcome of APRT deficiency in a large pediatric cohort. All pediatric cases of APRT deficiency confirmed at the same French reference laboratories between 1978 and 2010 were retrospectively reviewed. Twenty-one patients from 18 families were identified. The median age at diagnosis was 3 years. Diagnosis was made after one or more episodes of nephrolithiasis (17 patients), after urinary tract infection (1 patient), and by family screening (3 patients). The diagnosis was based on stone analysis and microscopic examination of urine and/or enzymatic determination of APRT on red blood cells. All children had null APRT enzyme activity in erythrocytes. APRT gene sequencing was performed on 18 patients, revealing six homozygous and 12 compound heterozygous mutations. At diagnosis, half of the patients had decreased kidney function, and two children presented with acute renal failure. Allopurinol treatment was given to all patients at a median dose of 9 mg/kg/day. After a median follow-up of 5 years, all patients showed stabilization or improvement of kidney function, normal growth and development, and six patients had recurrence of nephrolithiasis. Based on these results, we conclude that an excellent outcome can be achieved in children with APRT deficiency who receive the proper treatment.

Childhood onset diabetes posttransplant in a girl with TCF2 mutation.

Heterozygous mutations of TCF2 (transcription factor 2) have been associated with maturity onset diabetes of the young, renal malformations, hyperuricemia, and occasionally internal genital malformations in female. We report a female patient with bilateral renal hypodysplasia and de novo heterozygous TCF2 gene mutation. At the age of 9 yr, she developed transient ketoacidosis immediately posttransplant, temporarily requiring insulin. During glucocorticoid tapering, impaired glucose tolerance persisted and overt insulin-dependent diabetes mellitus developed 1 yr later. Pathogenic factors which might have played a role in the acceleration of diabetes were (i) switch from cyclosporine to tacrolimus, (ii) weight excess, and (iii) cytomegalovirus infection. TCF2 analysis might, therefore, be of interest in patients with congenital abnormalities of the kidney and the urinary tract in order to improve posttransplant management in terms of steroid and tacrolimus exposure.

Tubular nuclear accumulation of Snail and epithelial phenotypic changes in human myeloma cast nephropathy.

The transcription factor Snail is an important repressor of E-cadherin gene expression. It plays a key role in the induction of epithelial-mesenchymal transition, an essential process important not only in embryonic development and tumor progression but also in organ fibrogenesis. We studied the expression of Snail by immunohistochemistry, along with several epithelial phenotypic changes suggestive of epithelial-mesenchymal transition, in 14 patients with multiple myeloma cast nephropathy. This nephropathy is characterized by a rapid progression toward fibrosis. As controls, we used normal kidneys and kidneys from patients displaying an idiopathic nephrotic syndrome, a syndrome unassociated with renal fibrosis. We discovered that, in all patients with multiple myeloma nephropathy, a drastic accumulation of Snail is seen in the nuclei from tubular epithelial cells showing epithelial phenotypic changes. In contrast, normal and idiopathic nephrotic syndrome kidneys did not exhibit either of these markers. Snail, a major player in the process of epithelial-to-mesenchymal transition, is highly expressed by tubular epithelial cells during multiple myeloma nephropathy. It is, therefore, a potential target to prevent multiple myeloma kidneys from fibrosing. Intranuclear accumulation of Snail is a characteristic in phenotypically altered tubular cells from multiple myeloma kidneys. The epithelial-mesenchymal transition pathway could, therefore, be involved in the rapid renal fibrogenesis observed in this setting.

Prediction of high-grade vesicoureteral reflux after pediatric urinary tract infection: external validation study of procalcitonin-based decision rule.

BACKGROUND: Predicting vesico-ureteral reflux (VUR) ≥3 at the time of the first urinary tract infection (UTI) would make it possible to restrict cystography to high-risk children. We previously derived the following clinical decision rule for that purpose: cystography should be performed in cases with ureteral dilation and a serum procalcitonin level ≥0.17 ng/mL, or without ureteral dilatation when the serum procalcitonin level ≥0.63 ng/mL. The rule yielded a 86% sensitivity with a 46% specificity. We aimed to test its reproducibility. STUDY DESIGN: A secondary analysis of prospective series of children with a first UTI. The rule was applied, and predictive ability was calculated. RESULTS: The study included 413 patients (157 boys, VUR ≥3 in 11%) from eight centers in five countries. The rule offered a 46% specificity (95% CI, 41-52), not different from the one in the derivation study. However, the sensitivity significantly decreased to 64% (95%CI, 50-76), leading to a difference of 20% (95%CI, 17-36). In all, 16 (34%) patients among the 47 with VUR ≥3 were misdiagnosed by the rule. This lack of reproducibility might result primarily from a difference between derivation and validation populations regarding inflammatory parameters (CRP, PCT); the validation set samples may have been collected earlier than for the derivation one. CONCLUSIONS: The rule built to predict VUR ≥3 had a stable specificity (ie. 46%), but a decreased sensitivity (ie. 64%) because of the time variability of PCT measurement. Some refinement may be warranted.

Vesicoureteral reflux in children with urinary tract infection: comparison of diagnostic accuracy of renal US criteria.

PURPOSE: To directly compare various renal ultrasonography (US) criteria for vesicoureteral reflux (VUR) with voiding cystography, the reference method, for diagnostic accuracy in helping to determine an intermediate strategy of screening children who require cystography. MATERIALS AND METHODS: Institutional review board approval and parental consent were obtained for this prospective hospital-based cohort study involving children with urinary tract infections (UTIs). Renal length, ureteral dilatation, pelvic dilatation, and corticomedullary differentiation were analyzed and compared. One hundred seventeen patients (median age, 0.8 year; age range, 0.0-13.9 years) were included: 46 (39%) boys (median age, 0.3 year; age range, 0.5-13.9 years) and 71 girls (median age, 1.2 years; age range, 0.0-11.5 years). A two-level logistic regression model was used to analyze data, and diagnostic accuracy calculations were performed. RESULTS: Thirty-two (27%) children had all-grade VUR, and eight (7%) had VUR of grade 3 or higher. Only ureteral dilatation was significantly related to all-grade VUR (odds ratio [OR], 7.5; 95% confidence interval [CI]: 1.0, 58.2; P = .05), with 25% sensitivity (95% CI: 15%, 39%) and 88% specificity (95% CI: 83%, 92%). Ureteral, pelvic, and urinary tract dilatations were significantly associated with VUR of grade 3 or higher, with ORs of 20.2 (95% CI: 3.5, 118.2; P = .001), 13.7 (95% CI: 4.1, 46.0; P < .001), and 20.0 (95% CI: 4.4, 90.1; P < .001), respectively. The best compromise between sensitivity and specificity was achieved by using the ureteral dilatation criterion, which had 73% sensitivity (95% CI: 43%, 90%) and 88% specificity (95% CI: 84%, 92%) for high-grade VUR. CONCLUSION: Ureteral dilatation may yield the best accuracy for the US-based diagnosis of both all-grade and high-grade VUR. This US criterion, perhaps in combination with other predictors, might find a place in an evidence-based selective strategy for limiting cystography in children with UTIs.

Non-immunologic mechanisms of calcineurin inhibitors explain its antiproteinuric effects in genetic glomerulopathies.

It has been reported (this issue Pediatric Nephrology) that cyclosporine A (CyA) therapy in combination with corticosteroids, angiotensin-converting enzyme inhibitor, and an angiotensin receptor blocker decreased proteinuria in three patients with nephrotic syndrome (NS) due to WT1 mutations. Treatment with calcineurin inhibitors were found to induce a partial remission of proteinuria in several other children with genetic forms of NS, such as mutation in the podocine and in the phospholipase C epsilon gene. CyA therapy has also been reported to be beneficial to patients with Alport syndrome. Recent data have shown that the antiproteinuric effect of CyA in these cases may be due to a non-immunologic mechanism. CyA exerts an antiproteinuria effect by preventing the degradation of the actin organizing protein synaptodpodin and by a downregulation of TRPC6. This mechanism leads to the stabilization of the actin cytoskeleton in the kidney podocytes. This beneficial effect of CyA is interesting, but long-term results regarding function and nephrotoxicity are still missing.

Impressive renal damage after acute pyelonephritis in a child.

Urinary tract infection (UTI) is one of the most common bacterial infections in children, and its role in the pathogenesis of scarred kidney is debated. We report on a 7-year-old child who presented with severe UTI. The early (day 4) renal computed tomography (CT) scan showed normal-sized kidneys (110 mm on the left, 105 mm on the right), whereas the control CT scan and dimercaptosuccinic acid (DMSA) scan, performed 1 and 2 months later, respectively, showed a small scarred right kidney (60 mm) with a 12% residual function. An intermittent right vesicoureteral reflux (VUR) was diagnosed by direct isotopic cystography and then treated by Cohen vesicoureteral reimplantation. The patient remained free of infectious recurrence, hypertension, or renal function decrease. This report demonstrates that one episode of acute pyelonephritis can lead to severe renal scarring. Whereas antenatal lesions are thought to have a stronger role in the causal pathway for reflux nephropathy than is UTI in addition to VUR, this observation reminds us that UTI can truly play an important role in damaging kidneys.

Pharmacotherapy of lower urinary tract infections and pyelonephritis in children.

This review focuses on the treatment of urinary tract infections (UTI) in children. Acute pyelonephritis (an infection involving the renal parenchyma), acute cystitis (infection limited to the lower urinary tract) and asymptomatic bacteriuria (absence of clinical symptoms) have to be clearly distinguished. Whereas antibiotics are needed in pyelonephritis and cystitis, they should be used only exceptionally in cases of asymptomatic bacteriuria, as they may be potentially harmful and select more virulent bacteria. In case of pyelonephritis, there should be no delay in beginning the treatment in order to decrease the risk of long term complication in particular renal scars. Predisposing conditions for UTI should be evaluated carefully. New concepts concerning analysis of virulence profile or specific host immune response might bring more comprehension to UTI, but yet these concepts do not influence clinical practice. Any recommendation about (initial) antibiotic treatment should be regularly updated and adapted to local resistance profiles and to economical factors in different health systems.

Maternal uniparental heterodisomy of chromosome 17 in a patient with nephropathic cystinosis.

We report maternal uniparental disomy of chromosome 17 (mat UPD17) in a 2.5-year-old girl presenting infantile cystinosis. This patient was homozygous for the 57 kb deletion encompassing the CTNS gene, frequently found in patients from the European origin. The proband's mother was heterozygous for the deletion and the father did not carry the deletion. We carried out haplotype analysis with polymorphic markers spanning the whole chromosome 17. Informative markers showed the presence of two maternal alleles but no paternal allele for regions spanning the 17q arm and the proximal half of 17p, and only one maternal allele on the distal 17p arm. As deletion of half of 17p is probably not viable, these results suggest mat UPD17 with heterodisomy of 17q and proximal 17p and isodisomy of distal 17p. This is the first demonstration of mat UPD17, in particular of isodisomy 17p, in cystinosis.

Therapy-resistant anaemia in congenital nephrotic syndrome of the Finnish type--implication of EPO, transferrin and transcobalamin losses.

Congenital nephrotic syndrome of the Finnish type (CNF) is due to NPHS1 mutation and is responsible for a variety of urinary protein losses. We report the case of a 4-month-old girl with a particularly severe form (proteinuria approximately 150 g/l) of CNF. She developed severe non-regenerative anaemia requiring bi-monthly blood transfusions despite daily EPO (600 UI/kg) and iron supplementation. Epoetin pharmacokinetics revealed a urinary loss of 27% of the given dose within the first 24 h after IV injection. However, plasma levels remained increased after 24 h (228 UI/l). Plasma transferrin and transcobalamin levels were undetectable. Atransferrinaemia and atranscobalaminaemia seem to be responsible for disturbed erythropoiesis.

High NPHP1 and NPHP6 mutation rate in patients with Joubert syndrome and nephronophthisis: potential epistatic effect of NPHP6 and AHI1 mutations in patients with NPHP1 mutations.

Joubert syndrome (JS) is an autosomal recessive disorder that is described in patients with cerebellar ataxia, mental retardation, hypotonia, and neonatal respiratory dysregulation. Kidney involvement (nephronophthisis or cystic renal dysplasia) is associated with JS in one fourth of known cases. Mutations in three genes--AHI1, NPHP1, and NPHP6--have been identified in patients with JS. However, because NPHP1 mutations usually cause isolated nephronophthisis, the factors that predispose to the development of neurologic involvement are poorly understood. In an attempt to identify such genetic determinants, a cohort of 28 families with nephronophthisis and at least one JS-related neurologic symptom were screened for mutations in AHI1, NPHP1, and NPHP6 genes. NPHP1 and NPHP6 homozygous or compound heterozygous mutations were found in 13 (46%) and six (21%) unrelated patients, respectively. Two of the 13 patients with NPHP1 mutations carried either a heterozygous truncating mutation in NPHP6 or a heterozygous missense mutation in AHI1. Furthermore, five patients with NPHP1 mutations carried the AHI1 variant R830W, which was predicted to be "possibly damaging" and was found with significantly higher frequency than in healthy control subjects and in patients with NPHP1 mutations without neurologic symptoms (five of 26 versus four of 276 and three of 152 alleles; P < 0.001 and P < 0.002, respectively). In contrast to the variable neurologic and milder retinal phenotype of patients with NPHP1 mutations, patients with NPHP6 mutations presented with a more severe neurologic and retinal phenotype. In conclusion, NPHP1 and NPHP6 are major genes of nephronophthisis associated with JS. Epistatic effects that are provided by heterozygous NPHP6 and AHI1 mutations and variants may contribute to the appearance of extrarenal symptoms in patients with NPHP1 mutations.

Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy syndrome with renal failure: impact of posttransplant immunosuppression on disease activity.

CONTEXT: Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) is a rare autosomal recessive disorder caused by mutations in the gene AIRE (autoimmune regulator). APECED affects mainly endocrine organs resulting in hypoparathyroidism, adrenocortical failure, diabetes mellitus, hypogonadism, and hypothyroidism. Nonendocrine organ manifestations are autoimmune hepatitis, vitiligo, pernicious anemia, exocrine pancreatic insufficiency, and alopecia. APECED's first manifestation generally is mucocutaneous candidiasis presumably related to T cell dysfunction. PATIENT: A 5-yr-old Iranian girl presented first with pernicious anemia, exocrine pancreatic insufficiency, and nail candidiasis. She had renal dysfunction due to chronic interstitial nephritis (CIN), which progressed to end-stage renal failure. She was transplanted 1 yr later. Common causes of CIN were excluded. APECED was suspected first because she developed progressively hypoparathyroidism, adrenocortical failure, glucose intolerance, and hypothyroidism. RESULTS: Genetic analysis revealed a large homozygous deletion (g.424_2157del1734), spanning exons 2-4, in the AIRE gene. The predicted protein, if it is produced, has only 44 amino acids (exon 1) in common with the wild-type protein. Immunosuppression after the first renal transplant included prednisone, azathioprine, and cyclosporine A. Multiple acute rejection episodes occurred. Chronic rejection resulted in lost graft and she was retransplanted 2 yr later. Surprisingly, all APECED-related symptoms including candidiasis and autoantibody levels decreased, presumably due to the reinforced immunosuppression (tacrolimus, mycophenolate mofetil, prednisone). CONCLUSIONS: This is the first report of an APECED patient with CIN resulting in end-stage renal failure. Clinical and biological improvement was observed under posttransplant multidrug immunosuppression including tacrolimus and mycophenolate mofetil.

Renal phenotypes related to hepatocyte nuclear factor-1beta (TCF2) mutations in a pediatric cohort.

The hepatocyte nuclear factor-1beta encoded by the TCF2 gene plays a role for the specific regulation of gene expression in various tissues such as liver, kidney, intestine, and pancreatic islets and is involved in the embryonic development of these organs. TCF2 mutations are known to be responsible for the maturity-onset diabetes of the young type 5 associated with renal manifestations. Several observations have suggested that TCF2 mutations may be involved in restricted renal phenotypes. Eighty children (median age at diagnosis 0.2 yr) with renal cysts, hyperechogenicity, hypoplasia, or single kidneys were studied. Quantitative multiplex PCR amplification of short fluorescence fragments for the search of large genomic rearrangements and sequencing for the detection of point mutations were performed. TCF2 anomalies were detected in one third of patients (25 of 80). The main alteration was the complete deletion of the TCF2 gene detected in 16 patients. Family screening revealed de novo TCF2 anomalies in nine of 17 probands with a high prevalence of deletions (seven of nine). TCF2 anomalies were associated with bilateral renal anomalies (P < 0.001) and bilateral cortical cysts (P < 0.001). However, abnormal renal function, detected in 40% of patients, was independent of the TCF2 genotype. No difference in renal function or severity of renal morphologic lesions was observed between patients with a TCF2 deletion and those with point mutations. In conclusion, TCF2 molecular anomalies are involved in restricted renal phenotype in childhood without alteration of glucose metabolism. These findings have important implications in the diagnosis of patients with renal dysplasia with cysts and their follow-up.