Complement gene mutations in children with C3 glomerulopathy: do they affect the response to mycophenolate mofetil?

BACKGROUND: C3 glomerulopathy (C3G) is a complement-mediated disease. Although genetic studies are not required for diagnosis, they are valuable for treatment planning and prognosis prediction. The aim of this study is to investigate the clinical phenotypes, kidney survival, and response to mycophenolate mofetil (MMF) treatment in pediatric C3G patients with and without mutations in complement-related genes. METHODS: Sixty pediatric C3G patients were included, divided into two groups based on complement-related gene mutations. Demographic and clinical-pathological findings, treatment modalities, and outcome data were compared, and Kaplan-Meier analysis was performed for kidney survival. RESULTS: Out of the 60 patients, 17 had mutations. The most common mutation was in the CFH gene (47%). The mean age at diagnosis was higher in the group with mutation (12.9 ± 3.6 vs. 11.2 ± 4.1 years, p = 0.039). While the patients without mutation most frequently presented with nephritic syndrome (44.2%), the mutation group was most likely to have asymptomatic urinary abnormalities (47.1%, p = 0.043). Serum parameters and histopathological characteristics were similar, but hypoalbuminemia was more common in patients without mutation. During 45-month follow-up,10 patients progressed to chronic kidney disease stage 5 (CKD5), with 4 having genetic mutation. The time to develop CKD5 was longer in the mutation group but not significant. MMF treatment had no effect on progression in either group. CONCLUSIONS: This study is the largest pediatric C3G study examining the relationship between genotype and phenotype. We showed that the mutation group often presented with asymptomatic urinary abnormalities, was diagnosed relatively late but was not different from the without mutation group in terms of MMF treatment response and kidney survival.

Utility of continuous performance test (MOXO-CPT) in children with pre-dialysis chronic kidney disease, dialysis and kidney transplantation.

BACKGROUND: Children with chronic kidney disease and on kidney replacement therapy may have neurocognitive and psychosocial disorders. Although kidney transplantation improves quality of life, psychological problems may exist in children who undergo kidney transplantation. Herein, we aimed to investigate attention-deficit hyperactivity disorder-like symptoms with MOXO-continuous performance test in children with pre-dialysis chronic kidney disease, dialysis and kidney transplantation. METHODS: The MOXO-continuous performance test measures four domains of attention-deficit hyperactivity disorder-like symptoms, including attention, timeliness, hyperactivity and impulsivity. Patients with at least three scores < - 1.5 standard deviations were considered as positive to MOXO-continuous performance test. Test scores of the pre-dialysis chronic kidney disease, dialysis (divided into peritoneal dialysis and hemodialysis subgroups) and kidney transplantation groups were compared. Correlations of test scores with the patient's clinical and laboratory characteristics and effects of hospitalizations and schooling were assessed. RESULTS: Seventy-two patients aged 13.3 ± 3.4 years (23 with kidney transplantation, 23 on dialysis and 26 with pre-dialysis chronic kidney disease) were evaluated. Overall MOXO-continuous performance test positivity was 29%. No differences were detected between the three groups concerning total or z scores. Attention and timeliness z scores were significantly higher in females (p = 0.004 and p = 0.008, respectively). Age was positively correlated to attention and timeliness total scores (p = 0.000, r = 0.445 and p = 0.004, r = 0.243, respectively), and inversely correlated to hyperactivity total scores (p = 0.000, r = - 0.415). CONCLUSIONS: Prevalence of attention-deficit hyperactivity disorder-like symptoms in the study population was much higher than that of pediatric attention-deficit hyperactivity disorder. We believe that the MOXO-continuous performance test is a valid supportive measure for evaluation of attention-deficit hyperactivity disorder diagnosis in children with various stages of chronic kidney disease or on kidney replacement therapy.

The Role of Platelet-Lymphocyte Ratio and Neutrophil-Lymphocyte Ratio in Predicting the Delayed Graft Function in Pediatric Renal Transplant Patients.

OBJECTIVES: Delayed graft function is a common adverse outcome after renal transplant. Attempts for early prediction and prevention of delayed graft function are often challenging and misleading. Herein, we investigated for the first time the correlation between delayed graft function and preoperative noninvasive hematologic parameters to predict the possible adverse outcomes for renal transplant in pediatric patients. MATERIALS AND METHODS: In this study, preoperative hematologic parameters of 51 pediatric renal transplant recipients followed between 2015 and 2021 were analyzed retrospectively. The selected 16 renal transplant patients with delayed graft function and 35 patients without delayed graft function had no concomitant comorbidities. The cutoff values for platelet-to-lymphocyte ratio of <5 and neutrophilto- lymphocyte ratio of <175 were considered low. RESULTS: We retrospectively evaluated a total of 51 (male/female, 33/18) pediatric kidney transplant recipients with a median age of 12 (interquartile range, 8-18) years. Median level of circulating lymphocytes was significantly higher in patients with delayed graft function compared with patients without delayed graft function (2 vs 1, P = .040). The preoperative low values for platelet-to-lymphocyte ratio and neutrophil-to-lymphocyte ratio were more prevalent in recipients who developed delayed graft function versus those who did not develop delayed graft function (68.8% vs 31.4% [P = .014] and 68.8% vs 34.3% [P = .023], respectively). CONCLUSIONS: Pretransplant low platelet-to-lymphocyte ratio and neutrophil-to-lymphocyte were associated with increased number of delayed graft dysfunction. These novels and noninvasive inflammatory biomarkers may contribute to an early prediction of delayed graft function in pediatric kidney transplant recipients.

Long-Term Outcomes of Kidney Transplant Recipients With Juvenile Nephronophthisis.

OBJECTIVES: Nephronophthisis is the most common genetic cause of kidney failure in childhood. Treatment for nephronophthisis is symptomatic, and kidney transplant is a good treatment option when kidney failure has developed. We reported the outcomes of kidney transplant recipients with primary diagnosis of juvenile nephronophthisis who were followed-up in our center. MATERIALS AND METHODS: We retrospectively examined medical records of 17 kidney transplant patients with a primary diagnosis of juvenile nephronophthisis. We compared this group of 17 patients with kidney transplant recipients who had other etiologies of kidney failure in terms of transplant age, donor type, immunosuppressive treatment, acute rejection, graft loss rates, and glomerular filtration rates at 1 and 5 years posttransplant (N = 180 total analyzed). RESULTS: Among 180 kidney transplant recipients, the 17 patients (9.4%) with nephronophthisis had a mean age of 12.6 ± 4.3 years and mean follow-up time posttransplant of 79.5 ± 41.9 months. Five of 17 patients received a kidney transplant from a deceased donor (29.4%), and the remaining 12 patients (70.6%) received transplants from living related donors. Preemptive kidney transplant was performed in 4 patients (23.5%). There was a statistically significant difference (P < .05) in terms of acute rejection between patients with nephronophthisis (17.6%) versus patients with other primary diagnoses (34%). However, the patients with nephronophthisis versus those with other primary diagnoses were similar (P > .05) in terms of transplant age (12.6 ± 4.3 vs 13.8 ± 6.7 years, respectively) and follow-up time (79.5 ± 41.9 vs 59.1 ± 38.8 months, respectively). Donor type, immunosuppressive treatment, and 1-year (96.7 ± 23.2 vs 97.6 ± 28.4 mL/min/1.73 m2) and 5-year (84.7 ± 31.1 vs 86.7 ± 21.7 mL/min/1.73 m2) glomerular filtration rates were also similar (P > .05) between groups. CONCLUSIONS: Posttransplant prognosis was good among kidney transplant recipients with juvenile nephronophthisis.

Association Between Vitamin D Deficiency and Anemia in Pediatric Kidney Transplant Recipients.

OBJECTIVES: The association between vitamin D deficiency and anemia is known. Vitamin D deficiency and anemia are common in kidney transplant recipients. We examined the relationship between vitamin D levels and anemia in pediatric kidney transplant recipients. MATERIALS AND METHODS: We reviewed retrospectively the data of 75 pediatric kidney transplant recipients (0-18 years of age). Patients were evaluated in 3 groups according to serum 25-hydroxyvitamin D levels (<20, 20-30, and >30 ng/mL) in the first year posttransplant: group 1 was the vitamin D deficiency group, group 2 was the vitamin D insufficiency group, and group 3 was normal vitamin D level group, respectively. Groups were compared in terms of anemia parameters, calcium, phosphorus, alkaline phosphatase, and parathyroid hormone levels, as well as infection, rejection, and graft loss status. All patients included in the study were grouped as those with anemia and without anemia, and the 2 groups were compared in terms of vitamin D levels, serum parathyroid hormone values, estimated glomerular filtration rate, and infection, rejection, and graft loss status. RESULTS: There were 41 patients (54.7%) in group 1, 24 patients (32%) in group 2, and 10 patients (13%) in group 3. There were 65 patients (86.7%) with vitamin D deficiency/insufficiency. When groups were compared, the hematocrit level was found to be lower in groups 1 and 2 (P < .05) and ferritin level was found to be lower in group 1 (P < .05). Anemia was present in 20 patients (26.6%): 61% of patients with anemia had vitamin D deficiency and 33% had vitamin D insufficiency (P > .05). In total, 94% of patients with anemia had vitamin D deficiency/insufficiency. CONCLUSIONS: Vitamin D deficiency/insufficiency is common in pediatric kidney transplant recipients. Vitamin D levels should be measured, especially in all kidney transplant recipients with persistent anemia. Thus, risk factors associated anemia can be reduced by treating the deficiency/insufficiency.

Use of Eculizumab in Pediatric Patients with Late Antibody-Mediated Rejection After Kidney Transplantation.

Late antibody-mediated rejection triggered by donor-specific antibodies is a leading cause of kidney allograft failure. Effective treatment options for late antibody-mediated rejection are limited in renal transplant recipients. Here, we report 2 pediatric cases of severe late antibody-mediated rejection resistant to conventional immunosuppressive therapy who were successfully treated with eculizumab. Two patients who fulfilled the late antibody-mediated rejection diagnostic criteria (positive donor-specific antibodies, elevated mean fluorescence index, acute and/or chronic morphological lesions in the microvasculature, and abnormal kidney function test) were included in this study. Both patients were previously unsensitized with negative panel-reactive antibody. Case 1 was a 12-year-old male patient with kidney failure secondary to vesicoureteral reflux who underwent related-living donor kidney transplantation 2 years ago. Eleven months later, he was diagnosed with late antibody-mediated rejection. Despite an aggressive conventional immunosuppressive regimen, signs of rejection persisted. After the patient was treated with 2 doses of eculizumab, his mean fluorescence index dropped and serum creatinine decreased from 3.8 to 1.5 mg/dL. Case 2 was an unsensitized 16-year-old male patient with kidney failure secondary posterior urethral valve who underwent related-living donor kidney transplantation 4 years ago. Two years later, he was diagnosed with late antibody-mediated rejection. Despite an aggressive conventional immunosuppressive regimen, signs of rejection persisted. After treatment with 2 doses of eculizumab, his mean fluorescence index dropped and serum creatinine decreased from 2.1 to 1.01 mg/dL. In both patients, eculizumab therapy effectively reduced the markers of late antibody-mediated rejection and improved the kidney function.

COVID-19 Infections in Pediatric Renal Transplant Recipients.

OBJECTIVES: The new coronavirus SARS-CoV-2 (COVID-19) first appeared in Turkey in March 2020, spread rapidly, and caused many deaths. Although COVID-19 is mostly a respiratory disease, it can cause kidney and multiorgan failure in some cases. We believe that by sharing information about the course and effects of COVID-19 infection in kidney transplant recipients receiving long-term immunosuppressive therapy our understanding will improve. MATERIALS AND METHODS: Between March 2020 and October 2021, COVID-19 was researched in kidney transplant recipients under the age of 20 years who were followed at the Baskent University Transplantation Center. We documented the clinical characteristics and prognosis of pediatric kidney transplant recipients with COVID-19 disease. RESULTS: Our study group included 23 patients with COVID-19 infection from 215 pediatric kidney transplant recipients. The mean age of the patients was 14.6 ± 4.7 years; there were 9 female patients. The mean follow-up time posttransplant was 62.3 ± 43.2 months. In 13 patients (56.5%), fever was the most frequent symptom. Most patients (n = 18, 78%) had minor symptoms and recovered completely after receiving supportive treatment. Four patients (17%) required hospitalization. One was diagnosed with COVID-19 infection 1 week after being treated with rituximab for acute antibody-mediated rejection. That patient died because of significant lung disease and multiorgan failure. CONCLUSIONS: Despite the fact that most of our pediatric transplant recipients had mild symptoms of COVID-19, we believe that particular caution should be observed in patients who have recently received intensive immunosuppressive medications. As a result of potential new vaccines, national immunization programs, and the emergence of novel virus strains, the clinical picture may change in the future. We believe that, as information sharing increases, we will learn more about COVID-19 in renal transplant recipients.

How important urolithiasis is under 2 years of age?

Urolithiasis (UL) is a common health problem in the world and the observed incidence of this disease is increasing in the infantile period. The study included cases of UL diagnosed before the age of two who had a comprehensive analysis for possible etiologic variables and were followed for a minimum of 6 months. Of the 60 patients included in the study, 37 were male, and the male/female ratio was 1.6. The average age at diagnosis is 8.5 ± 4.5 months. Of the cases diagnosed 41 (68.3%) were before than 1 year of age. The average time for follow-up is 28.9 ± 22.6 months. There was a family history of stone disease in 41 (68.3%) cases. Twenty-four (40%) patients were treated for dehydration at least once before stone disease was identified. The number of patients presenting with symptoms is 43 (71.7%). Restlessness was noted as the main symptom. In 17 (28.3%) patients, stone disease was found incidentally. Metabolic causes (n: 19, 31.6%) were determined to be the most common underlying cause, followed by UTI-related causes (n: 12, 20%). During the follow-up, 57 (64%) of the stones spontaneously disappeared. The size of 16 (18%) stones reduced, while the size of eleven remained same (13%). Following their absence, nine (15%) of the stones reappeared. The essential strategy is to identify high-risk groups, to closely monitor them, and to take preventative interventions against modifiable conditions such as dehydration if possible.

Bismuth intoxication resulting in acute kidney injury in a pregnant adolescent girl.

Çelebi-Tayfur A, Yaradilmis RM, Ulus F, Çaltik-Yilmaz A, Özayar E, Kosar B, Büyükkaragöz B, Horasanli E. Bismuth intoxication resulting in acute kidney injury in a pregnant adolescent girl. Turk J Pediatr 2019; 61: 292-296. Bismuth intoxication is a rare cause of acute kidney injury (AKI) and is usually reversible by appropriate therapeutic measures. We present here a case of an adolescent pregnant girl who developed AKI due to an overdose of colloidal bismuth subcitrate (CBS, total amount of 6 g). She received parenteral chelating agent dimercaprol for 14 days. Continuous venovenous hemodiafiltration (CVVHD) with high-flux membrane was carried out in the first 3 days of chelating therapy and intermittent hemodialysis for 11 days, thereafter. The patient recovered clinically and was discharged after 21 days. She gave birth to a healthy term boy. At the last visit, the baby was 6 months old with normal growth and development as well as normal kidney functions. Neither deterioration in renal functions nor emergence of proteinuria was recorded in the patient during follow-up care after hospital discharge. In cases of AKI due to an overdose of CBS, treatment with dimercaprol combined with high flux hemodiafiltration and subsequently hemodialysis appears to be both useful and safe for bismuth elimination.

A Novel Mutation in the AVPR2 Gene Causing Congenital Nephrogenic Diabetes Insipidus

Objective: Congenital nephrogenic diabetes insipidus (CNDI) is a rare inherited disorder characterized by a renal insensitivity to arginine vasopressin (AVP). In the majority of the cases, CNDI is caused by mutations in the arginine vasopressin receptor 2 (AVPR2) gene. Our objective is to report a novel mutation in the AVPR2 gene causing CNDI in a 6-year-old boy, presenting with growth failure and dull normal cognitive functions. Methods: The proband was the third off-spring of non-consanguineous parents and had polyuria (4.3 L/day), polydipsia (5 L/day). The diagnosis of CNDI was established by a water-deprivation test and a desmopressin challenge test. Genetic studies were also carried out in the mother, siblings and affected family members, since excessive fluid intake and diuresis were also reported in these individuals. All exons of the AVPR2 gene for all participants were amplified and sequenced. Bioinformatics analysis for wild-type and mutant AVPR2 were obtained with Swiss-Model and UCSF Chimera 1.10.2. Results: A novel, hemizygous, missense mutation was identified at the position 80th in exon 2 (p.H80Y) of AVPR2 in the proband. The proband's mother, maternal aunt and grandmother were heterozygous and his maternal uncle was hemizygous for this mutation. Bioinformatic analysis indicates this mutation would cause significant conformational changes in protein structure. Conclusion: p.H80Y mutation will cause inappropriate folding of the protein compromising water homeostasis via AVPR2 and AVP and leading to diabetes insipidus. We suggest that future functional investigations of the H80Y mutation may provide a basis for understanding the pathophysiology of the NDI in patients with this variant.

Influence of body mass index on pediatric urolithiasis.

OBJECTIVE: In recent years, there has been increased incidence of urolithiasis in children. Changing nutritional patterns and sedentary lifestyles predispose to urolithiasis, as well as to the global rise in obesity. It has been established that the prevalence of high body mass index (BMI) is increasing in the pediatric population. The aim of the present study was to incorporate 24-h urine metabolic analysis results with BMI values to evaluate the tendency towards stone formation in children. METHODS: Eighty-four children were recruited to the study, stratified into three BMI categories as low, normal, or upper. All patients were evaluated with 24-h urine analysis results. Patients with a secondary cause of stone formation such as hyperparathyroidism, cystinuria, primary hyperoxaluria, inflammatory bowel disease, cystic fibrosis, history of prematurity and/or use of drug, recurrent urinary tract infection, and urinary tract anomaly were excluded. Additionally, it was ensured that none of the patients were taking specific medication or diet that could alter their acid-base metabolism and calcium, oxalate, and uric acid levels. RESULTS: Mean BMI of patients was 21.6 ± 2.9 kg/m(2). LBMI was found in 52 (61.9%), N-BMI in 20 (23.8%), and U-BMI in 12 (14.3%) of the patients. No significant differences were present between the three groups for stone sizes and numbers. The patients' characteristics and 24-h urine parameters for BMI groups are presented in the Table. DISCUSSION: In the literature, several studies have focused on the relationship between obesity and pediatric urinary stone disease. However, only a few evaluated the urinary metabolic analysis in pediatric patients. We have encountered different results from mainly adult studies and some pediatric studies. Our study shows that U-BMI children are not under greater risk for urolithiasis than the other groups. An important portion of our study group was in the L-BMI group; nevertheless we cannot conclude that having a low BMI predisposes to urolithiasis based on the urinary metabolic evaluation as well as the stone sizes and numbers. The N-BMI group has increased risk factors for urolithiasis rather than the other groups, according to results of 24-h urine analysis. CONCLUSION: The results of our study indicate that BMI itself could not be considered as a separate and definite risk factor for urolithiasis development in children. Although the mechanisms and causative factors for urinary stone formation are better defined in adults, further studies investigating these parameters in children are warranted.

Long-term prognosis of idiopathic nephrotic syndrome in children.

BACKGROUND: To investigate the demographic, clinical and laboratory data of the children with idiopathic nephrotic syndrome (INS), and to determine prognostic factors that affect the clinical outcome of the patients. METHODS: Medical charts of 372 patients diagnosed to have INS and followed up at least 5 years between January 1990 and December 2008 were evaluated, respectively. After initial demographic, clinical and laboratory findings of the patients were documented, therapeutic protocols, prognosis and prognostic factors were investigated. RESULTS: 299 of the patients (80.4%) were steroid responsive and 73 (19.6%) were not. Focal segmental glomerulosclerosis (FSGS) was observed in 57%, minimal change disease (MCD) in 20.6% and diffuse mesengial proliferation in 21.9% renal biopsy materials. Steroid sensitivity was higher in patients with MCD and under the age of five years. Resistance to steroids was higher in children with FSGS. Complete remission was achieved in 96% of patients who were sensitive to steroids and in 46.6% who were resistant. 15% of patients who were steroid resistant developed chronic kidney disease (CKD). CONCLUSION: Intercurrent infections and response to steroid therapy are the most important factors affecting the prognosis of the disease.

The relation between treatment and prognosis of childhood membranoproliferative glomerulonephritis.

BACKGROUND: The prognostic factors, the outcome and the most favorable treatment regimen are not entirely known for children with membranoproliferative glomerulonephritis (MPGN). MPGN is a rarely observed disease more prevalent in adolescents, so we aimed to review the clinical and histological properties, treatments and the outcome of our patients who were diagnosed as MPGN. METHODS: Fifty-one children - diagnosed with MPGN - were selected from biopsy records in Dr. Sami Ulus Maternity and Children's Hospital Pediatric Nephrology Department from January 1999 to January 2011. A retrospective analysis was made of 33 regularly followed children. RESULTS: Thirty-three patients were identified, 13 female and 20 male. Their age groups at presentation ranged from 4 to 15 years. The following duration was 26-144 months (mean 74). Following the initial treatment, 20 (60%) patients achieved complete remission. Six patients with nephrotic syndrome and one with non-nephrotic proteinuria showed partial remission. The condition of one patient with nephrotic syndrome was unchanged with the persisting symptoms. The one patient with nephrotic syndrome and four others with non-nephrotic proteinuria did not respond to initial treatment as their renal functions decreased gradually. CONCLUSION: We concluded that only degree of tubulointerstitial damage on the initial biopsy is determinative for prognosis of childhood MPGN. If the patient receives high doses of steroid therapy in the early stages, their treatment is more likely to be successful. The effect of immunosuppressive treatment on MPGN is not clear.