The Clinical and Mutational Spectrum of 69 Turkish Children with Autosomal Recessive or Autosomal Dominant Polycystic Kidney Disease: A Multicenter Retrospective Cohort Study.

INTRODUCTION: Autosomal recessive polycystic kidney disease (ARPKD) is associated with pathogenic variants in the PKHD1 gene. Autosomal dominant polycystic kidney disease (ADPKD) is mainly associated with pathogenic variants in PKD1 or PKD2. The present study aimed to identify the clinical and genetic features of Turkish pediatric ARPKD and ADPKD patients. METHODS: This multicenter, retrospective cohort study included 21 genetically confirmed ARPKD and 48 genetically confirmed ADPKD patients from 7 pediatric nephrology centers. Demographic features, clinical, and laboratory findings at presentation and during 12-month intervals were recorded. RESULTS: The median age of the ARPKD patients at diagnosis was lower than the median age of ADPKD patients (10.5 months [range: 0-15 years] vs. 5.2 years [range: 0.1-16 years], respectively, [p = 0.014]). At the time of diagnosis, the median eGFR in the ARPKD patients was lower compared to that of ADPKD patients (81.6 [IQR: 28.7-110.5] mL/min/1.73 m2 and 118 [IQR: 91.2-139.8] mL/min/1.73 m2, respectively, [p = 0.0001]). In total, 11 (52.4%) ARPKD patients had malnutrition; 7 (33.3%) patients had growth retardation at presentation; and 4 (19%) patients had both malnutrition and growth retardation. At diagnosis, 8 (16.7%) of the ADPKD patients had malnutrition, and 5 (10.4%) patients had growth retardation. The malnutrition, growth retardation, and hypertension rates at diagnosis were higher in the ARPKD patients than the ADPKD patients (p = 0.002, p = 0.02, and p = 0.0001, respectively). ARPKD patients with malnutrition and growth retardation had worse renal survival compared to the patients without (p = 0.03 and p = 0.01). Similarly, ADPKD patients with malnutrition had worse renal survival compared to the patients without (p = 0.002). ARPKD patients with truncating variants had poorer 3- and 6-year renal outcome than those carrying non-truncating variants (p = 0.017). CONCLUSION: Based on renal survival analysis, type of genetic variant, growth retardation, and/or malnutrition at presentation were observed to be factors associated with progression to chronic kidney disease (CKD). Differentiation of ARPKD and ADPKD, and identification of the predictors of the development of CKD are vital for optimal management of patients with ARPKD or ADPKD.

Can microalbuminuria be an indicator of renal involvement in pediatric Covid 19 patients?

BACKGROUND: Proteinuria (both tubular and glomerular in origin) and its implications are well-known features of adult patients with COVID19. However currently studies addressing proteinuria and its role in the outcome of kidney and patients of pediatric COVID 19 is scarce. We aimed to evaluate the presence of microalbuminuria in order to detect early renal involvement in pediatric COVID 19 patients. METHODS: We prospectively evaluated 100 pediatric patients hospitalized with COVID 19 between April and July 2020. Clinical presentations, laboratory findings and outcomes were investigated. Microalbuminuria was compared with the age, gender, disease severity, and hemoglobin, platelet, leukocyte count and serum CRP levels of the patients. RESULTS: Twenty seven out of 100 patients had microalbuminuria. Fourteen patients had mild and fourteen had moderate disease. There was not any significant relation according to age and gender. Microalbuminuria was not related to the severity of the disease. Also the mean microalbuminuria level did not differ according to the disease course. Hemoglobin, platelet, leukocyte counts and serum CRP levels were also were not correlated with microalbuminuria levels. CONCLUSION: Although there was no difference between the groups with different disease course; microalbuminuria is detected in an important ratio of pediatric patients with COVID 19 in this study. In the highlight of our findings we suggest that urinary findings of pediatric COVID patients should be carefully evaluated.

Endocan levels in children with renal hypodysplasia.

AIMS: Severe reduction in nephron numbers that are characteristic of renal hypodysplasia (RHD) are one of the cause of childhood chronic kidney disease (CKD). Glomerular hyperfiltration, glomerular hypertrophy, progressive glomerular scarring, and interstitial fibrosis due to reduced nephron number are risk factors for CKD. In recent years, studies on specific markers for early diagnosis of renal failure and mortality have been carried out. The objectives of this study were to identify serum and urinary endocan levels that are expressed in glomerular endothelial cells and tubular epithelial cells in RHD. MATERIALS AND METHODS: 29 children with RHD were compared to 26 healthy controls in terms of serum and urinary endocan levels. RESULTS: The mean serum endocan level in the RHD group and the control group was 700.72 ± 323.19 and 426.86 ± 233.14 pg/mL, respectively. The mean serum endocan level was significantly higher (p = 0.003) in the RHD group. The mean urinary endocan level in the RHD group was 63.62 ± 92.46 pg/mL, and in the control group it was 80.26 ± 142.49 pg/mL. The mean urinary endocan level did not change between groups (p = 0.95). There was also a significant correlation between serum endocan level and uric acid level in the study group (r = 0.325, p = 0.028). CONCLUSION: To our knowledge, this was the first study that evaluated serum and urinary endocan levels in children with RHD. Although serum endocan level was found to be significantly higher in patients with RHD, further studies are needed to validate whether endocan could serve as a marker of poor renal prognosis in RHD.

CD80 expression and infiltrating regulatory T cells in idiopathic nephrotic syndrome of childhood.

BACKGROUND: CD80 (also known as B7-1) is a co-stimulatory molecule that is expressed in biopsies and also excreted in urine in patients with minimal change disease (MCD) and focal segmental glomerulosclerosis (FSGS). CD80 is inhibited by the cytotoxic T-lymphocyte-associated-antigen 4 (CTLA4), which is mainly expressed on regulatory T cells (Tregs). Ineffective circulating Treg response is involved in the pathogenesis of nephrotic syndrome. In this study, we evaluated CD80 expression and infiltrating Tregs in children with MCD and FSGS. METHODS: Evaluation of CD80 expression and semi-quantitative evaluation of Tregs (FOXP3-positive CD4 T cells) were carried out in 31 kidney biopsies (12 MCD, 19 FSGS) with immunofluorescence and immunohistochemistry staining. RESULTS: All MCD sections were stained negative; whereas six out of 19 FSGS sections (all from steroid-resistant (SR) patients), including one from a Wilms' tumor 1 (WT1) mutation-positive FSGS patient, stained positive for anti-CD80 goat antibody, and negative for anti-CD80 rabbit antibody. FSGS biopsy specimens had significantly higher FOXP3-positive cells/mm2 compared with MCD and control samples (P < 0.001). Biopsy samples from SR-FSGS patients (n = 12) with positive CD80 staining (n = 6) had significantly less Tregs (FOXP3-positive CD4 T cells) compared with CD80 (-) biopsies (n = 6; P = 0.004). CONCLUSION: CD80 expression was not detected in the majority of the archival biopsy sections and the results were not consistent across the different antibodies. In the SR-FSGS sections, however, CD80-positive biopsies had decreased FOXP3-positive CD4 T cells, suggesting that a decreased anti-inflammatory milieu may be the cause of increased CD80 expression.

Rituximab for Children With Difficult-to-Treat Nephrotic Syndrome: Its Effects on Disease Progression and Growth.

Background: Since the early 2000s rituximab (RTX) has been thought of as an alternative treatment for steroid-sensitive nephrotic syndrome (SSNS) and steroid-resistant nephrotic syndrome (SRNS). Objective: This study aimed to determine the effects of RTX treatment on disease outcome and growth in pediatric SSNS and SRNS patients. Materials and Methods: The medical records of pediatric SSNS and SRNS patients that began RTX treatment at the mean age of 10.8 ± 5.1 years between 2009 and 2017 were retrospectively reviewed. Additionally, the effect of RTX on growth was evaluated based on patient height, weight, and BMI z scores. Results: The study included 41 children, of which 21 had SSNS and 20 had SRNS. Mean age at diagnosis of NS was 5.8 ± 4.7 years. Mean duration of post-RTX treatment follow-up was 2.3 ± 1.6 years. Among the SSNS patients, 6 and 11 patients were steroid free and calcineurin inhibitor free at the last follow-up visit, respectively. The 1-year cumulative steroid and calcineurin inhibitor doses both decreased after RTX treatment, as compared to before RTX (P = 0.001 and P = 0.015, respectively). The median height z-score at the time of RTX initiation was -1.2 and the median height z-score at the last follow-up visit was -0.6 (P = 0.044). The median BMI z-score decreased from 1.6 (IQR; 0.9-3.0) at the time RTX was initiated to 1.1 IQR; [(-0.7)-2.5] at the last follow-up visit (P = 0.007). At the last follow-up visit 4 SRNS patients had complete remission and 4 had partial remission. The 1-year cumulative steroid dosage in the SRNS patients decreased significantly after RTX, as compared to before RTX (P = 0.001). The median height z-score at the time of RTX initiation was -0.8 and the median height z-score at the last follow-up visit was -0.7 (P = 0.81). The median BMI z-score decreased from 0.3 at the time RTX was initiated to -0.1 at the last follow-up visit (P = 0.11). Conclusion: RTX has a more positive effect on disease outcome and growth in SSNS patients than in those with SRNS.

Do not Miss Rare and Treatable Cause of Early-Onset Hemolytic Uremic Syndrome: Cobalamin C Deficiency.

The most common disorder of vitamin B12 metabolism is methylmalonic aciduria and homocystinuria type cobalamin C (cblC), which accounts for most of the cases is referred to as cblC deficiency. Cobalamin deficiency is one of the causes of early-onset hemolytic uremic syndrome (HUS). Here, we present the cases of 2 infants with cobalamin deficiency who presented with early-onset HUS. The first patient was a 5-month-old female who was admitted to the hospital with seizure, pallor, and yellow-colored diarrheal stools. Initial laboratory examination showed direct Coombs test-negative hemolytic anemia. Later, she developed acute kidney injury and thrombocytopenia. Bone marrow aspiration showed megaloblastic features, and urinary examination showed elevated levels of methylmalonic acid (MMA), -methyl citrate, and 3-hydroxypropionic acid. Methionine-restricted diet, parenteral hydroxocobalamine, folinic acid, carnitine, and betaine were initiated. Hemolytic activity was -controlled with this treatment. Genetic screening showed homozygous mutation on the MMACHCgene (p.R161*[c.481C>T]). The second patient was a 3-month-old male infant who was admitted to the hospital with malaise and diarrhea. Laboratory examination showed direct Coombs test-negative hemolytic anemia with leukopenia. Later he developed acute kidney injury and thrombocytopenia. Bone marrow aspiration revealed megaloblastic changes. Urine organic acid test showed increased levels of MMA. Parenteral hydroxocobalamine, folinic acid, carnitine, and betaine were initiated. He died due to respiratory failure and cardiac arrest. Direct sequencing of MMACHC identified homozygous mutation, c.271dup A. CblC deficiency is an important cause of early-onset HUS and prompt diagnosis will provide specific treatment modalities.

The Clinical and Mutational Spectrum of Turkish Patients with Cystinosis.

BACKGROUND AND OBJECTIVES: Infantile nephropathic cystinosis is a severe disease that occurs due to mutations in the cystinosis gene, and it is characterized by progressive dysfunction of multiple organs; >100 cystinosis gene mutations have been identified in multiple populations. Our study aimed to identify the clinical characteristics and spectrum of cystinosis gene mutations in Turkish pediatric patients with cystinosis. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: We identified the clinical characteristics and spectrum of cystinosis gene mutations in Turkish patients with cystinosis in a multicenter registry that was established for data collection. The data were extracted from this registry and analyzed. RESULTS: In total, 136 patients (75 men and 61 women) were enrolled in the study. The most common clinical findings were growth retardation, polyuria, and loss of appetite. None of the patients had the 57-kb deletion, but seven novel mutations were identified. The most common mutations identified were c.681G>A (p.Glu227Glu; 31%), c.1015G>A (p.Gly339Arg; 22%), and c.18_21 del (p.Thr7Phefs*7; 14%). These mutations were associated with earlier age of disease onset than the other mutations. To understand the effects of these allelic variants on clinical progression, the mutations were categorized into two major groups (missense versus deletion/duplication/splice site). Although patients with missense mutations had a better eGFR at the last follow-up visit, the difference was not significant. Patients in whom treatment began at age <2 years old had later onset of ESRD (P=0.02). Time to ESRD did not differ between the patients with group 1 and group 2 mutations. CONCLUSIONS: The most common cystinosis gene mutations identified in Turkey were c.681G>A (p.Glu227Glu), c.1015G>A (p.Gly339Arg), and c.18_21 del (p.Thr7Phefs*7). Patients with less severe cystinosis gene mutations tend to have better kidney outcome.

Follow-up results of patients with ADCK4 mutations and the efficacy of CoQ10 treatment.

BACKGROUND: ADCK4-related glomerulopathy is an important differential diagnosis in adolescents with steroid-resistant nephrotic syndrome (SRNS) and/or chronic kidney disease (CKD) of unknown origin. We screened adolescent patients to determine the frequency of ADCK4 mutation and the efficacy of early CoQ10 administration. METHODS: A total of 146 index patients aged 10-18 years, with newly diagnosed non-nephrotic proteinuria, nephrotic syndrome, or chronic renal failure and end-stage kidney disease (ESKD) of unknown etiology were screened for ADCK4 mutation. RESULTS: Twenty-eight individuals with bi-allelic mutation from 11 families were identified. Median age at diagnosis was 12.4 (interquartile range [IQR] 8.04-19.7) years. Upon first admission, all patients had albuminuria and 18 had CKD (6 ESKD). Eight were diagnosed either through the screening of family members following index case identification or during genetic investigation of proteinuria in an individual with a history of a transplanted sibling. Median age of these 8 patients was 21.5 (range 4.4-39) years. CoQ10 supplementation was administered following genetic diagnosis. Median estimated glomerular filtration rate (eGFR) just before CoQ10 administration was 140 (IQR 117-155) ml/min/1.73m2, proteinuria was 1,008 (IQR 281-1,567) mg/m2/day. After a median follow-up of 11.5 (range 4-21) months following CoQ10 administration, proteinuria was significantly decreased (median 363 [IQR 175-561] mg/m2/day, P=0.025), whereas eGFR was preserved (median 137 [IQR 113-158] ml/min/1.73m2, P=0.61). CONCLUSIONS: ADCK4 mutations are one of the most common causes of adolescent-onset albuminuria and/or CKD of unknown etiology in Turkey. CoQ10 supplementation appears efficacious at reducing proteinuria, and may thereby be renoprotective.

Management of stone disease in infants.

Evaluating and treating renal stone disease in infants are technically challenging. In this study, we evaluated the surgical treatment of renal stones in children under 1 year of age. We retrospectively reviewed the records of patients under 1 year old who were treated with ESWL, endourological or open surgical procedures for renal stone disease between January, 2009 and December, 2012. The patients' age, gender, stone size, stone location and number, complications, stone-free status, and postoperative complications were recorded. 19 of 121 infants with a mean age of 10.2 ± 3.07 months were treated with surgical procedures. Six (75%) of eight cystinuria patients required a surgical intervention. Retrograde endoscopic management was performed in thirteen patients (63.4%) as an initial surgical approach. There were three major (15.7%) complications. The rate of open surgical procedures was 31.6% (6 of 19 infants). The cutoff value of stone size for open surgery was 10 mm. There was a significant relationship between the conversion to open procedures and stone size, stone location, and symptom presentation especially the presence of obstruction (p < 0.05). After repeated treatments, the stone clearance rate of RIRS reached 84.6%. Retrograde intrarenal surgery is an effective and safe treatment method for renal stones in infants and can be used as a first-line therapy in most patients under 1 year old. This is especially important if an associated ureteral stone or lower pole stone that requires treatment is present and for patients with cystinuria, which does not respond favorably to ESWL.