Mithat Büyükçelik

Disruption of PTPRO Causes Childhood-Onset Nephrotic Syndrome

Idiopathic nephrotic syndrome (INS) is a genetically heterogeneous group of disorders characterized by proteinuria, hypoalbuminemia, and edema. Because it typically results in end-stage kidney disease, the steroid-resistant subtype (SRNS) of INS is especially important when it occurs in children. The present study included 29 affected and 22 normal individuals from 17 SRNS families; genome-wide analysis was performed with Affymetrix 250K SNP arrays followed by homozygosity mapping. A large homozygous stretch on chromosomal region 12p12 was identified in one consanguineous family with two affected siblings. Direct sequencing of protein tyrosine phosphatase receptor type O (PTPRO; also known as glomerular epithelial protein-1 [GLEPP1]) showed homozygous c.2627+1G>T donor splice-site mutation. This mutation causes skipping of the evolutionarily conserved exon 16 (p.Glu854_Trp876del) at the RNA level. Immunohistochemistry with GLEPP1 antibody showed a similar staining pattern in the podocytes of the diseased and control kidney tissues. We used a highly polymorphic intragenic DNA marker-D12S1303-to search for homozygosity in 120 Turkish and 13 non-Turkish individuals in the PodoNet registry. This analysis yielded 17 candidate families, and a distinct homozygous c.2745+1G>A donor splice-site mutation in PTPRO was further identified via DNA sequencing in a second Turkish family. This mutation causes skipping of exon 19, and this introduces a premature stop codon at the very beginning of exon 20 (p.Asn888Lysfs*3) and causes degradation of mRNA via nonsense-mediated decay. Immunohistochemical analysis showed complete absence of immunoreactive PTPRO. Ultrastructural alterations, such as diffuse foot process fusion and extensive microvillus transformation of podocytes, were observed via electron microscopy in both families. The present study introduces mutations in PTPRO as another cause of autosomal-recessive nephrotic syndrome.

ACE Gene Polymorphism in Turkish Children with Nephrotic Syndrome

Since 1990, the role of angiotensin converting enzyme (ACE) gene polymorphism in various renal and cardiac diseases is still debated. This study comprised 71 pediatric patients with nephrotic syndrome, 47 males (66%) and 24 females (34%) with a mean age of 57.4 ± 37.6 months, and a control group of 83 healthy males (59%) and 57 healthy females (41%) with a mean age of 505 ± 160.5 months. The distribution of the ACE genotype in the control group was II, 11%; ID, 53%; and DD, 36%, and the nephrotic syndrome was II, 4%; ID, 78%; and DD, 18%. Angiotensin-converting enzyme genotypes were significantly different between patients and control groups (p<0.05). The study groups consisted of 52 (73%) with steroid-sensitive nephrotic syndrome (SNSS) and 19 (27%) with steroid-resistant nephrotic syndrome (SRNS). The distribution of the ACE genotype was II, 6%; ID, 75%; and DD, 19% in the SSNS population and ID, 84% and DD, 16% in the SRNS population. No statistically significant difference was found between steroid sensitivity and ACE genotypes (p=0.5). The results show that ACE I/D polymorphism does not contribute to the steroid resistance, even though this study indicates that the presence of the I/D genotype has a much higher risk—approximately 2.8 times—of having nephrotic syndrome. Further studies with a larger number of patients are needed.

Bartter syndrome and growth hormone deficiency: three cases.

BackgroundBartter syndrome is a rare autosomal recessive disorder characterized by hypokalemia, salt loss, and metabolic alkalosis. Short stature is one of the clinical manifestations in these children. Although polyuria, polydipsia, hypokalemia, and salt loss may be responsible for growth retardation, the exact pathogenesis of short stature in Bartter syndrome is not known.Case diagnosis and treatmentIn this study, we present three children diagnosed as having Bartter syndrome with short stature and growth hormone (GH) deficiency. After recombinant human growth hormone therapy (rhGH), their growth velocities were improved.ConclusionsThese results indicate that GH deficiency may contribute to short stature in children with Bartter syndrome, and rhGH therapy would be an excellent adjunctive treatment for short children with this syndrome whose condition is resistant to conventional therapies in terms of growth.

Urotensin-II: More Than a Mediator for Kidney

Human urotensin-II (hU-II) is one of the most potent vasoconstrictors in mammals. Although both hU-II and its receptor, GPR14, are detected in several tissues, kidney is a major source of U-II in humans. Recent studies suggest that U-II may have a possible autocrine/paracrine functions in kidney and may be an important target molecule in studying renal pathophysiology. It has several effects on tubular transport and probably has active role in renal hemodynamics. Although it is an important peptide in renal physiology, certain diseases, such as hypertension and glomerulonephritis, may alter the expression of U-II. As might be expected, oxidative stress, mediators, and inflammation are like a devils triangle in kidney diseases, mostly they induce each other. Since there is a complex relationship between U-II and oxidative stress, and other mediators, such as transforming growth factor β1 and angiotensin II, U-II is more than a mediator in glomerular diseases. Although it is an ancient peptide, known for 31 years, it looks like that U-II will continue to give new messages as well as raising more questions as research on it increases. In this paper, we mainly discuss the possible role of U-II on renal physiology and its effect on kidney diseases.

DD Genotype of ACE Gene in Boys: May it be a Risk Factor for Minimal Change Nephrotic Syndrome?

It has been shown that angiotensin-converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism affects the circulating and cellular levels of ACE and may be a risk factor in several renal diseases. We analyzed the association of ACE gene I/D polymorphism with the clinical presentation of minimal change nephrotic syndrome (MCNS) in a Turkish child population. This study consisted of 97 children with MCNS and 144 healthy controls. Genotyping of ACE gene was performed using polymerase chain reaction (PCR). The distributions of ACE genotypes were II in 13%, ID in 49%, and DD in 38% in patient group, and 9%, 49%, and 42% in control group, respectively. The frequency of the D allele was 63% and that of the I allele was 37% in patients. There were no relevant differences in the allele frequencies and genotypes of ACE I/D polymorphism between patients and controls. However, DD genotype was higher in boys in children with MCNS (78.4%. vs. 50.0%, p = 0.004). The frequencies of DD genotype and D allele in boys were 7.25 and 2.56 times higher than II genotype and I allele in the patient group, respectively. We suggest that DD genotype in boys may be one of the risk factors for MCNS.

Colchicine treatment in children with familial Mediterranean fever: is it a risk factor for neuromyopathy?

BACKGROUND We cared for a 17-year-old adolescent with familial Mediterranean fever under colchicine treatment. Because of the increased creatinine kinase level (3937 U/L) observed in this individual, we planned to assess all pediatric patients with familial Mediterranean fever under colchicine treatment to detect any resultant neuromyopathy. METHODS The study included 88 children with familial Mediterranean fever who were receiving colchicine. The patient with myopathy was not included in the study. Serum creatinine kinase levels were measured and nerve conduction studies were carried out in all patients. RESULTS The study included 88 patients (47 female, 53.4%) with an average age of 10.1 ± 3.35 years. The average period of colchicine use was 28.25 ± 17.66 months. Side effects of colchicine were detected in 10 patients (11%)--as diarrhea in eight patients, leukopenia in one patient, and hair loss in one patient. Nerve conduction studies determined incidental carpal tunnel syndrome in only one patient. CONCLUSIONS Our study did not suggest an elevated risk of neuromyopathy associated with the use of colchicine for familial Mediterranean fever.

Pediatric post-streptococcal glomerulonephritis: Clinical and laboratory data

Acute post‐streptococcal glomerulonephritis (APSGN) is the most common post‐infectious glomerulonephritis in childhood. The aim of this study was therefore to identify the possible risk factor(s) responsible for decreased glomerular filtration rate (GFR) in APSGN.

Prevalence of hypertension determined by ambulatory blood pressure monitoring (ABPM) and body composition in long-term survivors of childhood cancer

ABSTRACT Aim: In recent years, survival rates of childhood cancers have significantly increased, and occurrence of long-term adverse late effects (eg, insulin resistance, diabetes mellitus, metabolic syndrome, hypertension) has become increasingly important. Early diagnosis of obesity/hypertension in childhood is essential to avoid morbidity in the adulthood. Therefore, this study was aimed to determine the blood pressure (BP) profile by ambulatory BP monitoring (ABPM) method, and prevalence of hypertension, obesity, abdominal obesity among childhood cancer survivors. Material and method: The study was carried out with 52 cancer survivors. The ABPM measurement was performed during 24 hours. The anthropometric measurements of patients were performed using standardized protocols. The body composition analysis was performed with bioelectrical impedance analysis (BIA) method. Statistical significance was considered at p < 0.05. Results: The mean age of patients was 12.84 ± 3.88 years. Time off therapy ranged 24–125 month. The prevalence of prehypertension and hypertension were 57.7% and 9.6%, respectively. There was no statistically significant relationship between diagnosis and BP status (p = 0.59). The prevalence of obesity, and abdominal obesity were 1.9% and 30.4%, respectively. There was a positive correlation between waist circumference (WC) and time off therapy (p = 0.046). The WC was found to be higher in patients who received cranial irradiation (p = 0.048). Weight/WC were higher in patients who used corticosteroids in the treatment (p = 0.019). Conclusion: Careful follow up of BP, weight and WC is necessary for long-term cancer survivors to prevent complications. Especially patients who receive cranial radiotherapy and use corticosteroid are at increased risk of abdominal obesity.

A Pediatric Case Presented with Posterior Reversible Encephalopathy Due to Cystinosis: Case Report

52 ystinosis is an inherited autosomal recessive disorder, which the defect involves cystinosin, the membrane transport protein playing role in amino acid cystine metabolism. Thus, cystine accumulates in lysosomes and elicits the symptoms in childhood like end stage renal disease, secondary Fanconi syndrome (proximal renal tubular acidosis).1 Neurologic complications consisting of cystinosis encephalopathy, myopathy, stroke like episode with coma, hemiplegia and myopathy are seen later. A Pediatric Case Presented with Posterior Reversible Encephalopathy Due to Cystinosis: Case Report

Autoimmune Polyglandular Syndrome Type 3c with Ectodermal Dysplasia, Immune Deficiency and Hemolytic-Uremic Syndrome

Autoimmune polyglandular syndrome (APS) is a disorder which is associated with multiple endocrine gland insufficiency and also with non-endocrine manifestations. The pathophysiology of APS is poorly understood, but the hallmark evidence of APS is development of autoantibodies against multiple endocrine and non-endocrine organs. These autoantibodies are responsible for the dysfunction of the affected organs and sometimes may also cause non-endocrine organ dysfunction. The hemolytic-uremic syndrome (HUS) is a serious and life-threatening disease which develops due to many etiological factors including autoimmune disorders. Here, we present an unusual case of APS. Ectodermal dysplasia with immune deficiency and HUS occurred concomitantly in the same patient with APS type 3c. Once the autoantibody generation was initiated in the human body, development of multiple disorders due to organ dysfunction and also autoantibody-related diseases may have occurred.