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.

Characteristics and predictors of chronic kidney disease in children with myelomeningocele: a nationwide cohort study

BACKGROUND

Myelomeningocele (MMC) is highly prevalent in developing countries, and MMC-related neurogenic bladder is an important cause of childhood chronic kidney disease (CKD). This nationwide study aimed to evaluate demographic and clinical features of pediatric patients with MMC in Turkey and risk factors associated with CKD stage 5.

METHODS

Data from children aged 0-19 years old, living with MMC in 2022, were retrospectively collected from 27 pediatric nephrology centers. Patients > 1 year of age without pre-existing kidney abnormalities were divided into five groups according to eGFR; CKD stages 1-5. Patients on dialysis, kidney transplant recipients, and those with eGFR < 15 ml/min/1.73 m2 but not on kidney replacement therapy at time of study constituted the CKD stage 5 group.

RESULTS

A total of 911 (57.8% female) patients were enrolled, most of whom were expectantly managed. Stages 1-4 CKD were found in 34.3%, 4.2%, 4.1%, and 2.4%, respectively. CKD stage 5 was observed in 5.3% of patients at median 13 years old (range 2-18 years). Current age, age at first abnormal DMSA scan, moderate-to-severe trabeculated bladder on US and/or VCUG, and VUR history were independent risk factors for development of CKD stage 5 (OR 0.752; 95%; CI 0.658-0.859; p < 0.001; OR 1.187; 95% CI 1.031-1.367; p = 0.017; OR 10.031; 95% CI 2.210-45.544; p = 0.003; OR 2.722; 95% CI 1.215-6.102; p = 0.015, respectively). Only eight CKD stage 5 patients underwent surgery related to a hostile bladder between 1 and 15 years old.

CONCLUSION

MMC-related CKD is common in childhood in Turkey. A proactive approach to neurogenic bladder management and early protective surgery in selected cases where conservative treatment has failed should be implemented to prevent progressive kidney failure in the pediatric MMC population in our country.

Catastrophic antiphospholipid syndrome accompanied by complement regulatory gene mutation

BACKGROUND

Antiphospholipid syndrome (APS), particularly the catastrophic antiphospholipid syndrome (CAPS), is one of the rare causes of thrombotic microangiopathy (TMA). CAPS is the most severe form of APS, especially when accompanied by complement dysregulation, causes progressive microvascular thrombosis and failure in multiple organs. In this report, a case of CAPS with TMA accompanied by a genetic defect in the complement system is presented.

CASE

A 13-year-old girl was admitted to the hospital with oliguric acute kidney injury, nephrotic range proteinuria, Coombs positive hemolysis, refractory thrombocytopenia, a low serum complement C3 level and anti-nuclear antibody (ANA) positivity. The kidney biopsy was consistent with TMA. She was first diagnosed with primary APS with clinical and pathological findings and double antibody positivity. As initial treatments, plasmapheresis (PE) was performed and eculizumab was also administered following pulsesteroid and intravenous immunoglobulin treatments. Her renal functions recovered and she was followed up with mycophenolate mofetil, hydroxychloroquine, low dose prednisolone and low molecular weight heparin treatments. The patient presented with severe chest pain, vomiting and acute deterioration of renal functions a few months after the diagnosis of TMA. A CAPS attack was considered due to radiological findings consistent with multiple organ thrombosis and intravenous cyclophosphamide (CYC) was given subsequent to PE. After pulse CYC and PE treatments, her renal functions recovered, she is still being followed for stage-3 chronic kidney disease. Complement factor H-related protein I gene deletion was detected in the genetic study.

CONCLUSIONS

The clinical course of complement mediated CAPS tends to be worse. Complement system dysregulation should be investigated in all CAPS patients, and eculizumab treatment should be kept in mind if detected.

Molecular Aspects of Distal Kidney Tubular Acidosis in Children, Its Long-Term Outcome, and Relationship with Hyperammonemia

Objective:

We aimed to present the characteristics, genetic analysis results, long-term prognosis of our patients with distal kidney tubular acidosis, and the relationship between hyperammonemia and distal kidney tubular acidosis.

Materials and Methods:

Biochemical, clinical, and imaging findings were collected at presentation and the last clinic visit, and results of the genetic analysis were recorded.

Results:

Our study included 9 patients (3 female, 33%). The median age at diagnosis was 3 months, and the median follow-up period was 111 months. Height standard deviation scores were less than −2 in 4 (44%) patients at presentation and in 3 (33%) at the last clinic visit. The median estimated glomerular filtration rate was 98 mL/min/1.73 m² at presentation and 126 mL/min/1.73 m² at the last clinic visit. We have found 8 different types of mutations of 2 genes, including 6 in the ATP6V0A4 gene, 2 in the SLCA4A1 gene, and 2 of them were novel. At the time of presentation, nephrocalcinosis and hypercalciuria were present in all our patients, but at the last visit, only 1 patient had hypercalciuria. Sensorineural hearing loss was found in 4 of our patients with a mutation in the ATP6V0A4 gene. Serum ammonia levels were found to be high in 3 patients with mutations in the ATP6V0A4 gene.

Conclusion:

Adequate metabolic control is essential for optimal growth and preserved kidney function in distal kidney tubular acidosis patients. Distal kidney tubular acidosis may be associated with hyperammonemia. We recommend keeping potassium levels at high-normal levels to reduce ammonia levels, especially in the absence of acidosis.

Phenotypic and genotypic characteristics of children with bartter syndrome

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A Nationwide Retrospective Study in Turkish Children With Nephrocalcinosis

BACKGROUND

Nephrocalcinosis (NC) is defined as calcium deposition in the kidney parenchyma and tubules. This study aims to determine the etiology, risk factors and follow-up results of patients with NC in Turkey.

MATERIALS AND METHODS

Patients diagnosed with NC in the Pediatric Nephrology Department Units of 19 centers from all geographical regions of Turkey over a 10-year period (2010?2019) were included in the study. The medical records from the centers were reviewed and demographic data, admission complaints, medical history, systemic and genetic disorders, risk factors for NC, treatment details and presence of NC after one year follow-up were recorded retrospectively.

RESULTS

The study sample included 195 patients (88 females, 107 males). The mean age at diagnosis was 39.44±47.25 (0.5?208) months; 82/190 patients (43.2%) were diagnosed incidentally; 46/195 patients (23.6%) had an underlying disease; idiopathic hypercalciuria was detected in 75/195 (38.4%) patients. The most common systemic diseases were distal renal tubular acidosis in 11/46 patients (23.9%), primary hyperoxaluria in 9/46 patients (19.6%) and Bartter syndrome in 7/46 patients (15.3%). After one year of follow-up, NC resolved in 56/159 patients (35.2%) and they all did not have an underlying systemic disease.

CONCLUSION

The most common presentation of NC was incidental. Distal renal tubular acidosis and primary hyperoxaluria were the main systemic diseases leading to NC, while hypercalciuria was the most common metabolic risk factor. Nephrocalcinosis was found to remain in most of the patients at a one year follow-up. It may resolve particularly in patients with no underlying systemic disease.

Renal Biopsy Prognostic Findings in Children With Atypical Hemolytic Uremic Syndrome

BACKGROUND

The aim of this study was to investigate the histopathological findings in kidney biopsies in children with atypical hemolytic uremic syndrome (aHUS) and to determine whether specific pathological findings in aHUS have a prognostic value.

METHODS

Renal biopsy specimens of 29 patients who were recorded in the national Turkish aHUS registry database were available for review. Histopathological findings were compared with the clinical and laboratory features at the presentation and the final outcome.

RESULTS

The mean age at presentation and follow-up period was 4.9 ± 3.9 and 3.9 ± 3.0 years, respectively. The median time interval from the first symptom to biopsy was 10 days. Vascular thrombosis and interstitial fibrosis were significantly related to chronic kidney disease (CKD) requiring dialysis or kidney transplantation during follow-up (5.6-fold, for both). Glomerular necrosis, cortical necrosis, and glomerular sclerosis were markedly associated with CKD without dialysis (6.2-fold, 13.3-fold, and 8.8-fold, respectively). However, presence of endothelial swelling, subendothelial widening, and fragmented erythrocytes was found to be correlated with a favorable final outcome.

CONCLUSIONS

Presence of vascular thrombosis, cortical necrosis, and glomerular sclerosis in histopathological evaluation correlated with developing CKD. Chronic changes in the interstitial compartment were also related to poor prognosis, a finding that has been shown for the first time in pediatric aHUS cases.

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.

Polyarteritis nodosa in case of familial Mediterranean fever

Gökçe İ, Altuntaş Ü, Filinte D, Alpay H. Polyarteritis nodosa in case of familial Mediterranean fever. Turk J Pediatr 2018; 60: 326-330. Familial Mediterranean fever (FMF) is an autosomal recessive disease characterized by recurrent self-limited attacks of fever accompanied by peritonitis, pleuritis, and arthritis. Protracted febrile myalgia syndrome (PFMS) is a rare form of vasculitic disease which is an uncommon dramatic manifestation of FMF, characterized by severe crippling myalgia and high fever. Polyarteritis nodosa (PAN) is a systemic necrotizing vasculitis affecting medium or small arteries. It is rarely observed in children, but its incidence increases in the presence of FMF. In this article we described a 14-year-old child diagnosed with FMF associated with PAN. Physicians should be aware of this possible association.

Outbreak of Shiga toxin-producing Escherichia-coli-associated hemolytic uremic syndrome in Istanbul in 2015: outcome and experience with eculizumab

BACKGROUND

This study aims to identify epidemiological and clinical characteristics of patients and report our experience with eculizumab treatment during an outbreak of hemolytic uremic syndrome (HUS) caused by Shiga toxin-producing Escherichia coli (STEC) in Istanbul in 2015.

METHODS

Thirty-two children (21 females, median age 3.25 years) were included in this study. Demographic, clinical and laboratory data, and treatment details were retrospectively collected. Renal outcomes were assessed at last follow-up visit. To assess the effect of eculizumab on prognosis of STEC-HUS, subgroup analysis was performed on patients who required dialysis.

RESULTS

A high number of cases occurred within a certain region of Istanbul. Stool samples were cultured from 21 patients (65%), and enteroaggregative E. coli (EAEC; n = 7) and enterohemorrhagic E. coli (EHEC; n = 3) strains were detected. Rates of dialysis treatment, neurological manifestations, and death were 59%, 25%, and 3%, respectively. Mean follow-up duration was 8.6 ± 2.6 months (range 3-12 months). None of the patients (n = 25) was on dialysis at the final visit. The complete renal recovery rate was 54%. Nine patients were treated with eculizumab. At final follow-up visit, no differences in estimated glomerular filtration rate, proteinuria level, or hypertension incidence were observed between patients treated with eculizumab and those not treated with eculizumab.

CONCLUSIONS

An outbreak of EAEC occurred in a specific region of Istanbul. Livestock markets were suspected as the source. Evidence for beneficial effects of eculizumab on renal outcome was not clear in this cohort.

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.

Changes in Bacterial Resistance Patterns of Pediatric Urinary Tract Infections and Rationale for Empirical Antibiotic Therapy

Background:

The causative agent spectrum and resistance patterns of urinary tract infections in children are affected by many factors.

Aims:

To demonstrate antibiotic resistance in urinary tract infections and changing ratio in antibiotic resistance by years.

Study Design:

Retrospective cross-sectional study.

Methods:

We analysed antibiotic resistance patterns of isolated Gram (-) bacteria during the years 2011-2014 (study period 2) in children with urinary tract infections. We compared these findings with data collected in the same centre in 2001-2003 (study period 1.

Results:

Four hundred and sixty-five uncomplicated community-acquired Gram (-) urinary tract infections were analysed from 2001-2003 and 400 from 2011-2014. Sixty-one percent of patients were female (1.5 girls : 1 boy). The mean age of children included in the study was 3 years and 9 months. Escherichia coli was the predominant bacteria isolated during both periods of the study (60% in study period 1 and 73% in study period 2). Bacteria other than E. coli demonstrated a higher level of resistance to all of the antimicrobials except trimethoprim-sulfamethoxazole than E. coli bacteria during the years 2011-2014. In our study, we found increasing resistance trends of urinary pathogens for cefixime (from 1% to 15%, p<0.05), amikacin (from 0% to 4%, p<0.05) and ciprofloxacin (from 0% to 3%, p<0.05) between the two periods. Urinary pathogens showed a decreasing trend for nitrofurantoin (from 17% to 7%, p=0.0001). No significant trends were detected for ampicillin (from 69% to 71%), amoxicillin-clavulanate (from 44% to 43%), cefazolin (from 39% to 32%), trimethoprim-sulfamethoxazole (from 32% to 31%), cefuroxime (from 21% to 18%) and ceftriaxone (from 10% to 14%) between the two periods (p>0.05).

Conclusion:

In childhood urinary tract infections, antibiotic resistance should be evaluated periodically and empiric antimicrobial therapy should be decided according to antibiotic sensitivity results.

Vitamin D receptor gene polymorphisms in children with kidney stone disease

Subaşı B, Gökçe İ, Delil K, Alpay H. Vitamin D receptor gene polymorphisms in children with kidney stone disease. Turk J Pediatr 2017; 59: 404-409. Kidney stone disease has a multifactorial etiology involving the interaction of genetic and environmental factors. There is an increased risk of stone formation in the relatives of idiopathic stone patients, which can be explained up to 60% by genetic factors. This study was conducted to explore the association of vitamin D receptor (VDR) gene polymorphisms with the risk of urolithiasis (UL) in Turkish children. We investigated the VDR gene polymorphisms: ApaI, BsmI, TagI, Cdx2, FokI, in 52 children (26 boys, 26 girls) with UL and in 51 healthy children (22 boys, 29 girls) without UL. Apa I, BsmI, TagI, Cdx2, FokI genotypes were analyzed by Apa I, BsmI, TagI, Cdx2, FokI restriction enzyme digestion, respectively. The resulting alleles are designated as ABTCF (ApaI, BsmI, TagI, Cdx2, and FokI restriction site is absent), or abtcf (ApaI, BsmI, TagI, Cdx2, FokI restriction site is present), respectively. Genotype and allele frequencies were calculated, and the association with UL, hypercalciuria and hypocitraturia was investigated. Our data provide no statistically significant evidence for an association between UL and VDR ApaI, BsmI, TagI, Cdx2, and FokI genotype and allele frequencies. Patients with hypocitraturia and hypercalciuria were compared with the control group and no statistically significant difference was detected in terms of VDR gene ApaI, BsmI, TagI, Cdx2, and FokI polymorphisms and allele frequencies. Our data suggest that the VDR ApaI, BsmI, TagI, Cdx2, and FokI polymorphisms do not indicate a significant risk for UL.

Leptospirosis in a child with acute respiratory distress syndrome

Yeşilbaş O, Şevketoğlu E, Kıhtır HS, Hatipoğlu N, Yıldırım HM, Akyol MB, Aktay-Ayaz N, Gökçe İ. Leptospirosis in a child with acute respiratory distress syndrome. Turk J Pediatr 2017; 59: 688-692. Leptospirosis is an infectious vasculitis, which can occur with different clinical features. While it is generally a subclinical and self-limited infection; kidney and liver dysfunction, pulmonary hemorrhage, thrombocytopenia, and cardiovascular collapse may occurr. A six-year-old boy presented with acute respiratory distress syndrome, shock, thrombocytopenia-associated multiple organ failure, and persistent high fever secondary to leptospirosis. Persistent high fever was resistant to intravenous immunoglobulin and pulse steroid therapy. He was successfully treated with plasmapheresis and hemofiltration with endotoxin-cytokine cleaning filter. In conclusion; leptospirosis may cause thrombocytopenia-associated multiple organ failure, persistent high fever, and acute respiratory distress syndrome. Plasmapheresis and hemofiltration should be considered in cases of severe leptospirosis with multiorgan failure.

Clinical and histopathological features of asymptomaticpersistent microscopic hematuria in children

BACKGROUND/AIM

We analyzed the clinical and pathological features and prognosis of 106 children with persistent asymptomatic microscopic hematuria (PAMH) with or without mild proteinuria.

MATERIALS AND METHODS

This was a retrospective study of 106 children who were referred to our clinics from 2000 to 2013 for evaluation of PAMH.

RESULTS

Among the 106 patients, 69 (65%) were female and 37 (35%) were male. The patients were divided into two groups: 101 patients with isolated microscopic hematuria (IMH) and 5 patients with asymptomatic microscopic hematuria and mild proteinuria (AMHP). Renal biopsy was performed in all 5 children with AHMP: 2 patients had hereditary nephropathy and 2 patients had focal segmental glomerulosclerosis (FSGS). One biopsy specimen revealed nonspecific findings. Renal biopsy was performed in 9 children with IMH: 4 patients had hereditary nephropathy and 5 patients had nonspecific findings. None of the patients received any specific treatment prior to renal biopsy. During the follow-up period, none of the patients developed impaired renal function. Among all the children, only one patient with AMHP developed hypertension and 2 patients with IMH developed proteinuria.

CONCLUSION

Long-term follow-up must be done carefully for isolated microscopic hematuria and renal biopsy should be performed in selected cases.

Serum alkaline phosphatase levels in healthy children and evaluation of alkaline phosphatase z-scores in different types of rickets

OBJECTIVE

Serum alkaline phosphatase (ALP) levels show great variation with age and sex in children and adolescents. Additionally, different buffers used even in the same method cause variable results. This detail is not usually taken into account in the evaluation. We aimed to study pediatric age- and sex-specific reference ranges for ALP by colorimetric assay using p-nitrophenyl phosphate as substrate and diethanolamine as buffer and also to compare the ALP levels in patients with different types of rickets.

METHODS

1741 healthy children and adolescents (904 girls) were included in the study for normative data. 77 different ALP measurements from 38 nutritional rickets (NR), 7 vitamin D-dependent rickets (VDDR) and 8 hypophosphatemic rickets (HR) patients were included.

RESULTS

Reference values for ALP were constructed. ALP levels demonstrated a tetraphasic course with two peaks at infancy and puberty. There was no difference in ALP levels between boys and girls until puberty. However, higher ALP levels were noted at 10-11 years in girls (p=0.02) and at 12-13, 14-15, 16-17 years in boys (p<0.001). ALP levels start to decline after age 12 and 14 in girls and boys, respectively. Serum ALP levels were highest in the VDDR group and lowest in the HR group (median z-score values in HR, VDDR and NR were 3.6, 10.4 and 6.5, respectively; p<0.001). Similarly, plasma parathormone(PTH) levels ranged from highest to lowest in the VDDR, NR and HR groups (median values: 525, 237 and 98 pg/mL, respectively; p<0.001).

CONCLUSIONS

This normative data will provide a basis for better evaluation of ALP levels determined by the described method. Furthermore, use of z-scores gives a more precise assessment of changes in ALP levels in rickets and other bone disorders.