More than tubular dysfunction: cystinosis and kidney outcomes.

BACKGROUND: Cystinosis is a lysosomal storage disease that affects many tissues. Its prognosis depends predominantly on kidney involvement. Cystinosis has three clinical forms: nephropathic infantile, nephropathic juvenile and non-nephropathic adult. Proximal tubular dysfunction is prominent in the infantile form, whereas a combination of glomerular and tubular alterations are observed in the juvenile form. METHODS: Thirty-six children with nephropathic cystinosis were included in the study. Clinical features, molecular genetic diagnoses, and kidney outcomes of the patients were evaluated. RESULTS: Twenty-one children (58.3%) were male. The median age at diagnosis was 18.5 months. Twenty-eight patients (77.8%) had infantile nephropathic cystinosis, while eight (22.2%) had juvenile nephropathic cystinosis. An acute rapid deterioration of the kidney function with proteinuria, hypoalbuminemia, and nephrotic syndrome, was observed in 37.5% of patients with the juvenile form. The mean estimated glomerular filtration rate (eGFR) was 82.31 ± 37.45 ml/min/1.73m2 at diagnosis and 63.10 ± 54.60 ml/min/1.73m2 at the last visit (p = 0.01). Six patients (16.6%) had kidney replacement therapy (KRT) at the last visit. The median age of patients with kidney failure was 122 months. Patients with a spot urine protein/creatinine ratio < 6 mg/mg at the time of diagnosis had better kidney outcomes (p = 0.01). The most common allele was c.451A>G (32.6%). The patients with the most common mutation tended to have higher mean eGFR and lower leukocyte cystine levels than patients with other mutations. CONCLUSION: Glomerulonephritis may be a frequent finding in addition to the well-known tubular dysfunction in patients with cystinosis. Furthermore, our results highlight that the presence of severe proteinuria at the time of diagnosis is a relevant prognostic factor for kidney survival.

Kidney disease profile and encountered problems during follow-up in Syrian refugee children: a multicenter retrospective study.

BACKGROUND: Children are one of the most vulnerable groups in conflict zones, especially those with chronic diseases. This study aimed to investigate kidney disease profiles and problems during follow-up in a population of Syrian refugee children residing in Turkey. METHODS: Syrian refugee children aged between 0 and 18 years were included in the study. Demographic data, diagnosis, particular interventions due to nephrological problems, and problems encountered during follow-up were obtained from all participating pediatric nephrology centers. RESULTS: Data from 633 children from 22 pediatric nephrology centers were included. Mean age of the children was 94.8 ± 61.7 months and 375 were male (59%). 57.7% had parental consanguinity and 23.3% had a close relative(s) with kidney disease. The most common kidney diseases were congenital anomalies of the kidney and urinary tract (CAKUT) (31.0%), glomerular disease (19.9%), chronic kidney disease (CKD) (14.8%), and urolithiasis (10.7%). Frequent reasons for CAKUT were nonobstructive hydronephrosis (23.0%), vesico-ureteral reflux (18.4%), and neurogenic bladder (15.8%). The most common etiology of glomerular diseases was nephrotic syndrome (69%). Ninety-four children had CKD, and 58 children were on chronic dialysis. Six children had kidney transplantation. Surgical intervention was performed on 111 patients. The language barrier, lack of medical records, and frequent disruptions in periodic follow-ups were the main problems noted. CONCLUSIONS: CAKUT, glomerular disease, and CKD were highly prevalent in Syrian refugee children. Knowing the frequency of chronic diseases and the problems encountered in refugees would facilitate better treatment options and preventive measures.

Risk Assessment for BK Virus-Associated Hemorrhagic Cystitis After Pediatric Hematopoietic Stem Cell Transplant: A Single-Center Retrospective Cross-Sectional Study.

OBJECTIVES: BK virus-associated hemorrhagic cystitis is a common complication of allogeneic hematopoietic stem cell transplant. It is known to be associated with cyclophosphamide therapy and the intensity of the conditioning regimen as well as infection with the BK virus. Data are limited for BK virus-associated hemorrhagic cystitis in pediatric recipients of allogeneic hematopoietic stem cell transplant. Therefore, we aimed to identify the risk factors and etiology of BK virus-associated hemorrhagic cystitis and determine the factors that may improve the treatment efficacy. MATERIALS AND METHODS: Data from recipients of allogeneic hematopoietic stem cell transplant were retrospectively analyzed. These data included information about age, sex, underlying disease, the details of ablative conditioning, graft-versus-host disease prophylaxis, donor type, stem cell source, history of acute graft-versus-host disease, and cytomegalovirus reactivation. RESULTS: A total of 50 patients developed BK virusassociated hemorrhagic cystitis among 334 patients. Symptoms associated with BK virus-associated hemorrhagic cystitis manifested an average of 45.3 days after transplant. Most of the patients had grade 2 and grade 3 hemorrhagic cystitis. Risk factor analysis revealed that haploidentical donor type, treatment with busulfan and cyclophosphamide as part of conditioning regimen, and history of total body irradiation increased the risk of BK virus-associated hemorrhagic cystitis in the pediatric recipient population. CONCLUSIONS: We found that, despite current conditioning regimens, BK virus-associated infection still leads to a considerable incidence rate of hemorrhagic cystitis in pediatric recipients of allogeneic hematopoietic stem cell transplant. Patients with a haploidentical donor and a history of busulfan and cyclophosphamide treatment or total body irradiation had a higher risk of BK virus-associated hemorrhagic cystitis. Thus, we suggest that patients with these factors should be followed closely after allogeneic hematopoietic stem cell transplant.

Influenza and pneumococcus vaccination rates in pediatric dialysis patients in Europe: recommendations vs reality A European Pediatric Dialysis Working Group and European Society for Pediatric Nephrology Dialysis Working Group study

Background/aim: Children on dialysis are under increased risk of influenza and invasive pneumococcal disease. Although vaccination against these microorganisms are recommended in dialysis patients and despite the fact that these vaccines can reduce disease burden and rates of hospitalization due to infection, vaccination rates are below expected and desired. We aimed to evaluate influenza and pneumococcal vaccination and infection rates in European pediatric dialysis centers. Materials and methods: In 16 centers from 11 countries, 357 pediatric dialysis patients were evaluated retrospectively during 1 year of observation period between 01.01.2014 and 01.01.2015. Results: In all centers, vaccination policy included immunization of dialysis patients with inactive influenza vaccine and pneumococcal conjugate vaccine (PCV). Fifty percent of the centers recommended pneumococcal polysaccharide vaccine following routine PCV series. A significantly higher pneumococcal vaccination rate (43.9%) was seen in peritoneal dialysis (PD) patients compared to those on hemodialysis (HD) (32.9%) (p = 0.035), while the rates for influenza were similar (42.4% and 46.1% respectively, p = 0.496). Among all dialysis patients, 2.2% (n = 8) developed pneumonia and 6.4% (n = 23) was infected by Influenza. Pneumococcic pneumonia rate was 5% for 140 patients who received antipneumococcal vaccine, while only one pneumonia episode was recorded out of 217 unvaccinated patients (p = 0.007). The influenza virus infection rates were similar for patients vaccinated and nonvaccinated (7 % and 6 %, respectively). Conclusions: Although influenza and pneumococcal vaccines are highly recommended in pediatric dialysis patients, vaccination rates were lower than expected. Pneumococcal vaccination rates were higher in PD compared to the patients on HD. The rate of children with influenza infection was higher than pneumonia. The efficacy of influenza and pneumococcal vaccines was highlighted by the low infection rates. Higher pneumonia rates in patients vaccinated against pneumococcus compared to unvaccinated ones might be due to coexisting risk factors.

Predictors of poor kidney outcome in children with C3 glomerulopathy.

BACKGROUND: C3 glomerulopathy (C3G) is characterized by heterogeneous clinical presentation, outcome, and predominant C3 accumulation in glomeruli without significant IgG. There is scarce outcome data regarding childhood C3G. We describe clinical and pathological features, treatment and outcomes, and risk factors for progression to chronic kidney disease stage 5 (CKD5) in the largest pediatric series with biopsy-proven C3G. METHODS: Sixty pediatric patients with C3G from 21 referral centers in Turkey were included in this retrospective study. Patients were categorized according to CKD stage at last visit as CKD5 or non-CKD5. Demographic data, clinicopathologic findings, treatment, and outcome data were compared and possible risk factors for CKD5 progression determined using Cox proportional hazards model. RESULTS: Mean age at diagnosis was 10.6 ± 3.0 years and follow-up time 48.3 ± 36.3 months. Almost half the patients had gross hematuria and hypertension at diagnosis. Nephritic-nephrotic syndrome was the commonest presenting feature (41.6%) and 1/5 of patients presented with nephrotic syndrome. Membranoproliferative glomerulonephritis was the leading injury pattern, while 40 patients had only C3 staining. Patients with DDD had significantly lower baseline serum albumin compared with C3GN. Eighteen patients received eculizumab. Clinical remission was achieved in 68.3%. At last follow-up, 10 patients (16.6%) developed CKD5: they had lower baseline eGFR and albumin and higher frequency of nephrotic syndrome and dialysis requirement than non-CKD5 patients. Lower serum albumin and eGFR at diagnosis were independent predictors for CKD5 development. CONCLUSIONS: Children with C3G who have impaired kidney function and hypoalbuminemia at diagnosis should be carefully monitored for risk of progression to CKD5. Graphical abstract.

Evaluation of phenotypic and genotypic features of children with distal kidney tubular acidosis.

BACKGROUND: The present study aimed to assess genotype-phenotype correlations with long-term prognosis in children with distal kidney tubular acidosis (dKTA). The kidney function of children with dKTA could be impaired in the long-term. METHODS: Thirty-one children with dKTA from 23 families were included in the present study. Demographic features, growth parameters, clinical manifestations, follow-up results, and genetic analysis results of the patients were recorded. RESULTS: Eighteen children (58.1%) were male. The median age at diagnosis was 3 months. The median follow-up period was 77 months and the longest was 23.5 years. Eight (28.8%) patients had chronic kidney disease (CKD) stage 2 or 3. Three patients aged 24, 23, and 19 years had CKD stage 3 with an estimated glomerular filtration rate of 54, 57, and 48 mL/min/1.73 m2, respectively. Thirteen patients had mutations in the ATP6V0A4 gene, eight had mutations in the ATP6V1B1 gene, and three had mutations in the SLC4A1 gene. There was no significant correlation between molecular diagnosis and CKD. Growth retardation with a height below a standard deviation (SD) score of - 2 was found in 14 patients (45.1%) at the time of diagnosis. The mean height SD score at the last visit was significantly higher in patients who had adequate metabolic control at > 75% of all visits as compared with that in patients who did not. CONCLUSION: Patients with dKTA usually have a good clinical prognosis in childhood with appropriate treatment; however, dRTA is characterized by deterioration of kidney function in adulthood, particularly after puberty.

From infancy to adulthood: challenges in congenital nephrogenic diabetes insipidus.

Objectives Congenital nephrogenic diabetes insipidus (NDI) is a rare hereditary disorder which is characterized by unresponsiveness to arginine vasopressin (AVP) in collecting ducts and leads to polyuria and polydipsia. The wide clinical spectrum of congenital NDI can cause difficulties in early diagnosis. We aimed to evaluate clinical prognosis of children with congenital NDI in long-term period. Methods Nineteen children with congenital NDI followed up in Pediatric Nephrology Department were enrolled to the study. This study is a single-center retrospective study, which reports clinical follow-up and genetic results of children with congenital NDI. Results Presenting symptoms of patients were mostly dehydration and fever due to polyuria and polydipsia. Four male patients had bilateral nonobstructive hydroureteronephrosis (HUN) and neurogenic bladder which requires clean intermittent catheterization (CIC). One patient had intracranial calcification which is a rarely seen complication in congenital NDI due to recurrent hypernatremic dehydration and severe brain dehydration. The causative mutations were identified in all patients. The identified mutations in six of them (31.6%) were hemizygous mutations in AVPR2 gene and homozygous mutations of AQP2 gene in the rest 13 cases (68.4%). More than that, four of these mutations (two in AVPR2 and two in AQP2) were novel mutations. Noncompliance with the treatments is associated with high risk of morbidity due to neurogenic bladder and chronic kidney disease (CKD). Conclusions The prognosis of congenital NDI is good when diagnosis can be made early and treatment is started immediately. Genetic counseling and prenatal testing for hereditary diseases are recommended especially in regions with relatively higher rates of consanguineous marriages.

Retrospective Analysis of the Factors Affecting Growth Parameters in Turkish Children With Systemic Lupus Erythematosus.

OBJECTIVES: This study aims to investigate the growth parameters in Turkish children with systemic lupus erythematosus (SLE) and to compare these growth parameters according to the presence or absence of cyclophosphamide, rituximab treatment, cumulative corticosteroid dose, proliferative nephritis, and the last visit disease activity and damage index. PATIENTS AND METHODS: Medical data, growth parameters including z-scores for weight, height, and body mass index and parent-adjusted height z-scores of 45 juvenile SLE (jSLE) patients (5 males, 40 females; mean age 12.3±3.2 years; range 7.1 to 18 years) were retrospectively evaluated. Growth parameters were calculated by anthropometric references in Turkish children. The disease activity was assessed by the SLE Disease Activity Index 2000 (SLEDAI-2K). The disease outcome was measured by the Pediatric version of Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index. RESULTS: The median diagnostic delay was two months (range, 0-36 months). The median follow-up duration was 3.21 years (range, 0.63-9.48 years). Mean height z-score was significantly lower at last visit than at the time of diagnosis. The growth parameters did not differ according to age at disease onset, diagnostic delay, presence of proliferative nephritis, having cyclophosphamide and rituximab treatment and the last visit (SLEDAI-2K) scores. The median duration of corticosteroid treatment was 3.2 years (range, 0.6-9.4 years) and the median cumulative corticosteroid dosage was 13.9 g (range, 1.9-58 g) of methylprednisolone. The mean height z-score at last visit was significantly lower in those who received at least 10 g of cumulative dose of corticosteroid. The last visit mean parent-adjusted height z-scores did not differ significantly regarding the cumulative corticosteroid dose. CONCLUSION: The last visit height and parent-adjusted height z-scores of jSLE patients were significantly lower. The patients treated with at least 10 g of cumulative dose of corticosteroids had lower mean height z-score.

Phenotypic variability in two patients with tumor necrosis factor receptor associated periodic fever syndrome emphasizes a rare manifestation: Immunoglobulin A nephropathy.

Tumor necrosis factor receptor associated periodic fever syndrome (TRAPS) is caused by heterozygote mutations in TNFRSF1A, characterized by recurrent inflammatory attacks. In this report, we described two patients with different heterozygote mutations in TNFRSF1A. Patient 1, a 15-year-old male, had suffered from recurrent fever attacks accompanied by abdominal pain, eye manifestations, and myalgia with increased acute phase reactants since the age of 6-month. He had been unsuccessfully treated with colchicine for having familial Mediterranean fever without an identifiable MEFV mutation since the age of 4-year. At the age of 15 years, he was diagnosed with immunoglobulin (Ig) A nephropathy due to massive proteinuria and renal biopsy findings. Next generation sequencing revealed NM_001065.3: c.236C>T; p. (Thr79Met); T50M heterozygote mutation in TNFRFS1A. He was treated with methylprednisolone and cyclosporine for IgA nephropathy, thereafter with canakinumab for TRAPS. Patient 2, a 17-year-old female, had recurrent arthritis attacks accompanied by increased acute phase reactants for the last two months. She had neither fever attacks nor rashes or myalgia. Her physical examination was normal between attacks. Magnetic resonance imaging of both knees and ankles showed no signs of chronic arthritis. MEFV analyzes showed no mutation. Next generation sequencing revealed NM_001065.3: c.362G>A; p.(Arg121Gln); R92Q heterozygote mutation in TNFRFS1A. Arthritis attacks were treated successfully with ibuprofen thereafter. In conclusion, we wish to emphasize the diversity of the clinical manifestations between these two patients with distinct sequence variants in TNFRSF1A. Moreover, we presented a rare manifestation of TRAPS, IgA nephropathy.

Clinical manifestations and outcomes of 420 children with Henoch Schönlein Purpura from a single referral center from Turkey: A three-year experience.

Objectives: Henoch Schönlein Purpura (HSP) is the most common systemic vasculitis in childhood. We aimed to evaluate the clinical features, seasonal variation, treatment outcomes and the possible predicting factors related to outcome among a large cohort of pediatric HSP patients.Methods: We conducted a medical record review study between July 2016 and January 2019 and evaluated the clinical manifestations and potential risk factors for severe gastrointestinal (GI) involvement, biopsy-proven nephritis and relapses.Results: The study included 420 HSP patients, of which the mean age at diagnosis was 7.68 ± 3.15 years. Clinical manifestations were arthralgia and/or arthritis (n = 244, 58.1%), abdominal pain (n = 235, 56%), subcutaneous edema (n = 163, 38.8%), and renal involvement (n = 125, 29.8%). Disease recurred for at least once, in 69 (16.4%) patients and colchicine treatment yielded a favorable response in 11 of 12 relapsing patients, who did not respond to ibuprofen or steroids. Frequencies of renal involvement and biopsy-proven nephritis were higher in patients with severe GI involvement. Besides, patients with biopsy-proven nephritis had higher rates of abdominal pain, intussusception, severe GI involvement, and systemic steroid administration.Conclusion: We speculate that renal involvement, biopsy-proven nephritis and severe GI involvement can be related to each other. Colchicine may be effective in patients with relapsing disease.

Metformin Intoxication with Severe Renal Damage: An Adolescent Case Report.

Metformin is an oral antidiabetic medication which belongs to the class biguanide. Its most hazardous and life-threatening side effect is lactic acidosis which has been increasingly reported in recent years. Early diagnosis and aggressive treatment approaches have significantly reduced morbidity and mortality rates in metformin intoxication. In this case report, we emphasize the importance of early continuous renal replacement therapy in metformin-associated lactic acidosis in a 16-year-old patient who developed severe renal damage during the follow-up period of renal replacement therapy due to lactic acidosis after taking metformin in a suicide attempt.

Treatment and long-term outcome in primary distal renal tubular acidosis.

BACKGROUND: Primary distal renal tubular acidosis (dRTA) is a rare disorder, and we aimed to gather data on treatment and long-term outcome. METHODS: We contacted paediatric and adult nephrologists through European professional organizations. Responding clinicians entered demographic, biochemical, genetic and clinical data in an online form. RESULTS: Adequate data were collected on 340 patients (29 countries, female 52%). Mutation testing had been performed on 206 patients (61%); pathogenic mutations were identified in 170 patients (83%). The median (range) presentation age was 0.5 (0-54) years and age at last follow-up was 11.0 (0-70.0) years. Adult height was slightly below average with a mean (SD score) of -0.57 (±1.16). There was an increased prevalence of chronic kidney disease (CKD) Stage ≥2 in children (35%) and adults (82%). Nephrocalcinosis was reported in 88%. Nephrolithiasis was more common with SLC4A1 mutations (42% versus 21%). Thirty-six percent had hearing loss, particularly in ATP6V1B1 (88%). The median (interquartile range) prescribed dose of alkali (mEq/kg/day) was 1.9 (1.2-3.3). Adequate metabolic control (normal plasma bicarbonate and normocalciuria) was achieved in 158 patients (51%), more commonly in countries with higher gross domestic product (67% versus 23%), and was associated with higher height and estimated glomerular filtration rate. CONCLUSION: Long-term follow-up from this large dRTA cohort shows an overall favourable outcome with normal adult height for most and no patient with CKD Stage 5. However, 82% of adult patients have CKD Stages 2-4. Importance of adequate metabolic control was highlighted by better growth and renal function but was achieved in only half of patients.

Juvenile systemic lupus erythematosus: a single-center experience from southern Turkey.

OBJECTIVES: This study was conducted to analyze clinical characteristics, laboratory data, disease activity, and outcome of juvenile systemic lupus erythematosus (jSLE) patients from southern Turkey. METHODS: Fifty-three patients with jSLE diagnosed according to the revised American College of Rheumatology 1997 criteria between January 2005 and June 2018 were included in the present study. RESULTS: The median age at the diagnosis was 12.8 (range, 5.1-17.7) years. The female to male ratio was 9.6:1. The most prevalent clinical features were mucocutaneous involvement (96.2%) and constitutional manifestations (94.3%). Renal manifestations, hematological manifestations, and neuropsychiatric involvement were detected in 40 (75%), in 38 (71.7%), and in 13 (24.5%) patients, respectively. Renal biopsy was performed to 49 patients (92.5%). Class IV lupus nephritis (LN) (34%) and class II LN (20.4%) were the most common findings. Mycophenolate mofetil, cyclophosphamide with corticosteroid were the main treatment options. Eighteen patients received rituximab and one tocilizumab. The mean SLE Disease Activity Index (SLEDAI) score at the time of diagnosis was 22.47 ± 8.8 (range = 3-49), and 1.34 ± 1.85 (range = 0-7) at last visit. Twenty-one patients (39.6%) had damage in agreement with Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index (PedSDI; mean = 0.60 ± 0.94; range = 0-5) criteria. Growth failure was the most prevalent cause of damage (n = 13, 26%). One patient deceased due to severe pulmonary hemorrhage and multiple cerebral thromboses. CONCLUSION: jSLE patients in this cohort have severe disease in view of the higher frequency of renal and neurologic involvement. Nevertheless, multicenter studies are needed to make a conclusion for all Turkish children with jSLE.

Clinical and histopathological prognostic factors affecting the renal outcomes in childhood ANCA-associated vasculitis.

OBJECTIVE: Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitides (AAV) are very rare in childhood with an increased risk of morbidity and mortality. We aimed to evaluate renal prognostic factors in childhood AAV from the perspective of ANCA serotype, histopathological classification, and five-factor score (FFS). METHODS: Pediatric AAV patients from 11 referral centers in Turkey had been included to the study. The demographics, clinical findings, AAV subtypes, outcomes, and FFS were evaluated retrospectively. Kidney biopsies were classified histopathologically. RESULTS: Totally, 39 patients were enrolled in the study. Among all patients, 74.4% had renal involvement, 56.4% ear-throat-nose involvement, and 51.3% had musculoskeletal involvement. Proteinase 3 (PR3)-ANCA was positive in 48.7%, and myeloperoxidase (MPO)-ANCA was positive in 30.8%. 69.2% of patients had impaired renal function, and 28.2% had progressed to end-stage renal disease (ESRD) during the follow-up. At the time of diagnosis, FFS was ≥ 2 in 53.8%. The most common histopathologic classifications were as follows: crescentic type in 40.7% and sclerotic type in 25.9%. Gastrointestinal and renal involvement, MPO-ANCA positivity, serum creatinine levels, and impaired renal function during the follow-up were significantly higher in patients with FFS ≥ 2, compared to patients with FFS < 2. Patients with FFS ≥ 2 had more common crescentic, mixed and sclerotic histopathologic findings in biopsies. By logistic regression analysis forward method, the strongest single-risk factor among all the parameters was the initial level of creatinine in patients with ESRD, compared to the other patients (p = 0,007). CONCLUSIONS: Evaluation of the FFS, ANCA serology, and the creatinine levels may help to predict renal prognosis.

Concomitance of Familial Mediterranean Fever and Gitelman syndrome in an adolescent.

Atmis B, Kisla-Ekinci RM, Melek E, Bisgin A, Yilmaz M, Anarat A, Karabay-Bayazit A. Concomitance of Familial Mediterranean Fever and Gitelman syndrome in an adolescent. Turk J Pediatr 2019; 61: 444-448. Gitelman syndrome is a renal tubular salt-wasting disorder characterized by hypokalemic metabolic alkalosis with hypomagnesemia and hypocalciuria. Patients occasionally have symptoms in childhood, while diagnosis is often in adulthood. It is inherited by an autosomal recessive manner through SLC12A3 gene mutations. Familial Mediterranean Fever (FMF) is the most common autoinflammatory disorder, inherited by an autosomal recessive manner and characterized by recurrent fever and pleuritis, peritonitis, and synovitis. Mutations in MEditerrenean FeVer (MEFV) gene, coding pyrin protein are responsible for FMF. Both MEFV and SCL12A3 genes were located on chromosome 16. A 9-year-old boy was admitted to our department because of recurrent abdominal pain, fever, joint pain and swelling since he was three years old. He was diagnosed as FMF and MEFV gene sequencing revealed homozygous M694V (c.2080A > G) mutation. At the age of 14 years, polyuria, polydipsia, hypokalemia and mild hypomagnesemia had occurred. Patient was successfully treated with oral supplementation of potassium and magnesium along with colchicine. Molecular genetic analysis including SCL12A3 gene sequencing revealed homozygote IVS4-16G > A (c.602-16G > A) intronic splicing site mutation.

Renal features of Bardet Biedl syndrome: A single center experience.

Atmis B, Karabay-Bayazit A, Melek E, Bisgin A, Anarat A. Renal features of Bardet Biedl syndrome: A single center experience. Turk J Pediatr 2019; 61: 186-192. Bardet Biedl syndrome (BBS), is a multisystemic disorder which is described as a ciliopathy. BBS is a rare autosomal recessive disorder and 21 different BBS genes have been defined to date. BBS is characterized with dysmorphic extremities, retinitis pigmentosa, obesity, hypogenitalism, intellectual disabilility and renal structural abnormalities. Renal symptoms in patients with BBS, are nonspecific and often undetected until end-stage renal disease. Here, we were reported 23 children with BBS (12 females, 11 males) with renal abnormalities from a single center and defined their features. Age at diagnosis were very variable (2 days-16 years). Median age at diagnosis was 84 months. Mean follow-up period was 42 months. All 23 children had urinary tract abnormalities on renal ultrasonography. These abnormalities were polycysts (34.8%), hyperechogenic kidneys (34.8%), fetal lobulation (21.7%), hypoplasia on at least one kidney (21.7%) and hydronephrosis in at least one kidney (17.4%). Vesicoureteral reflux and neurogenic bladder detected 11.1% and 22.2% of patients who recieved a voiding cystourethrogram, respectively. Proteinuria was found in 39 % of patients. Hypertension was defined in 21.7% of patients. Six of 23 children (26%) in our cohort had proven mutations in BBS genes. Five of them (83.3%) had homozygous mutations in BBS10 gene and one of them had homozygous mutation in BBS2 gene. All of 23 children had retinitis pigmentosa, twenty two of them (95.6%) had learning disabilities/cognitive impairment and seventeen of them (82.6%) had obesity. Renal involvement is now accepted as a cardinal feature and the most important factor causing mortality in BBS.