Development of a tool for predicting HNF1B mutations in children and young adults with congenital anomalies of the kidneys and urinary tract.

BACKGROUND: We aimed to develop a tool for predicting HNF1B mutations in children with congenital abnormalities of the kidneys and urinary tract (CAKUT). METHODS: The clinical and laboratory data from 234 children and young adults with known HNF1B mutation status were collected and analyzed retrospectively. All subjects were randomly divided into a training (70%) and a validation set (30%). A random forest model was constructed to predict HNF1B mutations. The recursive feature elimination algorithm was used for feature selection for the model, and receiver operating characteristic curve statistics was used to verify its predictive effect. RESULTS: A total of 213 patients were analyzed, including HNF1B-positive (mut + , n = 109) and HNF1B-negative (mut - , n = 104) subjects. The majority of patients had mild chronic kidney disease. Kidney phenotype was similar between groups, but bilateral kidney anomalies were more frequent in the mut + group. Hypomagnesemia and hypermagnesuria were the most common abnormalities in mut + patients and were highly selective of HNF1B. Hypomagnesemia based on age-appropriate norms had a better discriminatory value than the age-independent cutoff of 0.7 mmol/l. Pancreatic anomalies were almost exclusively found in mut + patients. No subjects had hypokalemia; the mean serum potassium level was lower in the HNF1B cohort. The abovementioned, discriminative parameters were selected for the model, which showed a good performance (area under the curve: 0.85; sensitivity of 93.67%, specificity of 73.57%). A corresponding calculator was developed for use and validation. CONCLUSIONS: This study developed a simple tool for predicting HNF1B mutations in children and young adults with CAKUT.

Genotype-phenotype correlations in children with Gitelman syndrome.

BACKGROUND: This study aimed to analyze genotype-phenotype correlations in children with Gitelman syndrome (GS). METHODS: This multicenter retrospective study included 50 Korean children diagnosed with SLC12A3 variants in one or both alleles and the typical laboratory findings of GS. Genetic testing was performed using the Sanger sequencing except for one patient. RESULTS: The median age at the diagnosis was 10.5 years (interquartile range, 6.8;14.1), and 41 patients were followed up for a median duration of 5.4 years (interquartile range, 4.1;9.6). A total of 30 different SLC12A3 variants were identified. Of the patients, 34 (68%) had biallelic variants, and 16 (32%) had monoallelic variants on examination. Among the patients with biallelic variants, those (n = 12) with the truncating variants in one or both alleles had lower serum chloride levels (92.2 ± 3.2 vs. 96.5 ± 3.8 mMol/L, P = 0.002) at onset, as well as lower serum potassium levels (3.0 ± 0.4 vs. 3.4 ± 0.3 mMol/L, P = 0.016), and lower serum chloride levels (96.1 ± 1.9 vs. 98.3 ± 3.0 mMol/L, P = 0.049) during follow-up than those without truncating variants (n = 22). Patients with monoallelic variants on examination showed similar phenotypes and treatment responsiveness to those with biallelic variants. CONCLUSIONS: Patients with GS who had truncating variants in one or both alleles had more severe electrolyte abnormalities than those without truncating variants. Patients with GS who had monoallelic SLC12A3 variants on examination had almost the same phenotypes, response to treatment, and long-term prognosis as those with biallelic variants.

Clinical course of post-kidney transplant Schimke immuno-osseous dysplasia.

BACKGROUND: Schimke immuno-osseous dysplasia (SIOD) is a rare systemic disease characterized by short stature, proteinuria, and recurrent infections. Patients usually have spondyloepiphyseal dysplasia, and progressive steroid-resistant nephropathy that leads to kidney failure. However, their clinical course after kidney transplantation (KT) is not yet well known. Here, we present our experience with cases of SIOD treated at our institute. CASE PRESENTATION: Since 2014, three children have been diagnosed with nephropathy resulting from SIOD. They presented with proteinuria in the nephrotic range at 7, 5, and 3 years of age. Focal segmental glomerulosclerosis was confirmed and progressed to kidney failure approximately 2 years after proteinuria was detected. These patients underwent living-donor KT from their parents. After KT, Case 1 lost his graft within 7 months due to multi-organ failure caused by disseminated adenovirus infection and died. Case 2 experienced graft failure 5 years after KT due to acute rejection from poor compliance. In Case 3, the allograft was still functioning 6 years after KT with low-dose tacrolimus single medication (trough level < 5 ng/mL). Extra-renal manifestations progressed regardless of KT, namely, right renal vein thrombosis and pulmonary hypertension in Case 1, severe bilateral hip dysplasia and Moyamoya syndrome in Case 2, and neutropenia and thrombocytopenia in Case 3, in addition to recurrent infection. CONCLUSION: In SIOD patients, KT is complicated with recurrent infections due to their inherent immune dysfunction. Additionally, extra-renal symptoms may render the patients morbid despite the recovery of kidney function.

Efficacy of Burosumab in Adults with X-linked Hypophosphatemia (XLH): A Post Hoc Subgroup Analysis of a Randomized Double-Blind Placebo-Controlled Phase 3 Study.

The anti-fibroblast growth factor 23 monoclonal antibody burosumab corrects hypophosphatemia in adults with X-linked hypophosphatemia (XLH) and improves pain, stiffness, physical function, and fatigue. This post hoc subgroup analysis used data from the 24-week placebo-controlled period of a phase 3 study in 134 adults with XLH (ClinicalTrials.gov NCT02526160), to assess whether the benefits of burosumab are evident in 14 clinically relevant subgroups defined by baseline demographic and functional criteria, including sex, Brief Pain Inventory-short form (BPI-SF) Average And Worst Pain, region, race, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC®) Stiffness, Physical Function and Pain domains and total score, use of opioid/other pain medication, active fractures/pseudo-fractures, and 6-min walk test distance. There were no statistically significant interactions between any of the subgroups and treatment arm for any endpoint. Higher proportions of subjects achieved mean serum phosphate concentration above the lower limit of normal (the primary endpoint) with burosumab than with placebo in all subgroups. For the key secondary endpoints (WOMAC Stiffness and Physical Function; BPI-SF Worst Pain) individual subgroup categories showed improvements with burosumab relative to placebo. For additional efficacy endpoints, burosumab was favored in some subgroups but differences were not significant and confidence intervals were wide. For some endpoints the treatment effect is small at 24 weeks in all subjects. This subgroup analysis shows that burosumab was largely superior to placebo across endpoints in the 14 clinically relevant subgroup variables at 24 weeks and is likely to benefit all symptomatic adults with active XLH.

Burden of disease of X-linked hypophosphatemia in Japanese and Korean patients: a cross-sectional survey.

The burden of disease of X-linked hypophosphatemia (XLH) in East Asia is poorly understood. This was a cross-sectional study using an online questionnaire to evaluate health-related quality of life (HRQOL) and disease complications in Japanese and Korean patients with XLH. Adults with XLH and the caregivers of children <18 years of age with XLH in Japan and Korea were surveyed. Respondents disclosed demographic data, family history, diagnostic history, medical history, surgical history, disease-specific clinical symptoms, treatment, medications, and use of ancillary equipment. Patient-reported outcomes (PROs; the Western Ontario and McMaster Universities Osteoarthritis Index, the brief pain inventory, and the 36-item short form health survey version 2) were used to assess pain, disability, and HRQOL in adults. Of those surveyed, all 14 children (100%) and 30/32 adults (93.8%) were receiving treatment for XLH. However, despite oral phosphate and active vitamin D use, short stature, gait abnormalities, dental conditions, and decreased physical function were reported. Stapling of the growth plates was reported in 14.3% of children but no adults. Adult patients reported high rates of bone pain (59.4%) and joint pain (65.6%). Caregivers of children with XLH also reported the occurrence of bone pain (35.7%) and joint pain (35.7%). Many adult patients had a history of impaired renal function (9.5%), nephrocalcinosis (15.6%), hyperparathyroidism (15.6%), and parathyroidectomy (6.3%), all of which are associated with conventional XLH treatments. These data show that patients (both pediatric and adult) continue to have symptoms such as pain, disability, and various complications despite receiving conventional therapies.

Patient-Reported Outcomes from a Randomized, Active-Controlled, Open-Label, Phase 3 Trial of Burosumab Versus Conventional Therapy in Children with X-Linked Hypophosphatemia.

Changing to burosumab, a monoclonal antibody targeting fibroblast growth factor 23, significantly improved phosphorus homeostasis, rickets, lower-extremity deformities, mobility, and growth versus continuing oral phosphate and active vitamin D (conventional therapy) in a randomized, open-label, phase 3 trial involving children aged 1-12 years with X-linked hypophosphatemia. Patients were randomized (1:1) to subcutaneous burosumab or to continue conventional therapy. We present patient-reported outcomes (PROs) from this trial for children aged ≥ 5 years at screening (n = 35), using a Patient-Reported Outcomes Measurement Information System (PROMIS) questionnaire and SF-10 Health Survey for Children. PROMIS pain interference, physical function mobility, and fatigue scores improved from baseline with burosumab at weeks 40 and 64, but changed little with continued conventional therapy. Pain interference scores differed significantly between groups at week 40 (- 5.02, 95% CI - 9.29 to - 0.75; p = 0.0212) but not at week 64. Between-group differences were not significant at either week for physical function mobility or fatigue. Reductions in PROMIS pain interference and fatigue scores from baseline were clinically meaningful with burosumab at weeks 40 and 64 but not with conventional therapy. SF-10 physical health scores (PHS-10) improved significantly with burosumab at week 40 (least-squares mean [standard error] + 5.98 [1.79]; p = 0.0008) and week 64 (+ 5.93 [1.88]; p = 0.0016) but not with conventional therapy (between-treatment differences were nonsignificant). In conclusion, changing to burosumab improved PRO measures, with statistically significant differences in PROMIS pain interference at week 40 versus continuing with conventional therapy and in PHS-10 at weeks 40 and 64 versus baseline.Trial registration: ClinicalTrials.gov NCT02915705.

Lower albumin level and longer disease duration are risk factors of acute kidney injury in hospitalized children with nephrotic syndrome.

BACKGROUND: Children with nephrotic syndrome (NS) are at an increased risk of acute kidney injury (AKI) and the incidence of AKI in this population is reportedly increasing. This study aimed to investigate the incidence, clinical profiles, and risk factors of AKI in hospitalized children with NS through a nationwide study. METHODS: This retrospective multicenter study included 14 pediatric nephrology centers in Korea. From 2013 to 2017, a total of 814 patients with idiopathic NS were cared for at participating centers. Among them, 363 patients were hospitalized for NS and investigated in this study. RESULTS: A total of 363 children with NS were hospitalized 574 times. AKI occurred in 93 admissions (16.2%) of 89 patients: 30 (32.3%) stage 1; 24 (25.8%) stage 2; and 39 (41.9%) stage 3. Multivariate logistic regression analysis showed that longer disease duration, lower albumin level, and methylprednisolone pulse treatment were significantly associated with AKI development in hospitalized children with NS. AKI was associated with a longer hospital stay than non-AKI (median 10 vs. 7 days, P = 0.001). Among 93 admissions, 85 (91.4%) episodes recovered from AKI without complication, whereas 6 (6.5%) progressed to advanced chronic kidney disease (CKD). CONCLUSIONS: AKI is not uncommon in hospitalized children with NS, and its incidence in this nationwide study was 16.2%. Risk factors for AKI in hospitalized children with NS include longer disease duration, lower albumin level, and methylprednisolone pulse therapy. Pediatric NS patients with these characteristics should be under more strict scrutiny for the occurrence of AKI. Graphical abstract.

Intellectual Functioning of Pediatric Patients with Chronic Kidney Disease: Results from the KNOW-Ped CKD.

BACKGROUND: Chronic kidney disease (CKD) has a negative impact on growth and development in children and is a risk factor for neurocognitive impairment; however, there is limited research on the cognitive function of children and adolescents with CKD. This study therefore aimed to investigate the mean intelligence and risk factors for low intelligence in children and adolescents with CKD. METHODS: Eighty-one patients with CKD under 18 years old were included in the KoreaN cohort study for Outcomes in patients With Pediatric Chronic Kidney Disease (KNOW-Ped CKD). Participants completed either the Wechsler Intelligence Scale for Children (6-16 years), or Wechsler Adult Intelligence Scale (> 16 years). RESULTS: The mean full-scale intelligence quotient (IQ) was 91 ± 19; 24.7% of participants scored a full-scale IQ below 80. Participants with a short stature (height Z scores < -1.88), failure to thrive (weight Z scores < -1.65), more severe CKD stage (≥ IIIb), longer duration of CKD (≥ 5 years), and those who were Medicare or Medicaid beneficiaries, had significantly lower mean full-scale IQs. CONCLUSION: On linear regression analysis, the association between the full-scale IQ, and longer duration of CKD and growth failure, remained significant after controlling for demographic and clinical variables. It is therefore necessary to investigate cognitive impairment in pediatric patients with CKD who exhibit growth failure or for a longer postmorbid period. It is believed that early interventions, such as kidney transplantation, will have a positive effect on IQ in children with CKD, as the disease negatively affects IQ due to poor glomerular filtration rate over time. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT02165878.

Common risk variants in NPHS1 and TNFSF15 are associated with childhood steroid-sensitive nephrotic syndrome.

To understand the genetics of steroid-sensitive nephrotic syndrome (SSNS), we conducted a genome-wide association study in 987 childhood SSNS patients and 3,206 healthy controls with Japanese ancestry. Beyond known associations in the HLA-DR/DQ region, common variants in NPHS1-KIRREL2 (rs56117924, P=4.94E-20, odds ratio (OR) =1.90) and TNFSF15 (rs6478109, P=2.54E-8, OR=0.72) regions achieved genome-wide significance and were replicated in Korean, South Asian and African populations. Trans-ethnic meta-analyses including Japanese, Korean, South Asian, African, European, Hispanic and Maghrebian populations confirmed the significant associations of variants in NPHS1-KIRREL2 (Pmeta=6.71E-28, OR=1.88) and TNFSF15 (Pmeta=5.40E-11, OR=1.33) loci. Analysis of the NPHS1 risk alleles with glomerular NPHS1 mRNA expression from the same person revealed allele specific expression with significantly lower expression of the transcript derived from the risk haplotype (Wilcox test p=9.3E-4). Because rare pathogenic variants in NPHS1 cause congenital nephrotic syndrome of the Finnish type (CNSF), the present study provides further evidence that variation along the allele frequency spectrum in the same gene can cause or contribute to both a rare monogenic disease (CNSF) and a more complex, polygenic disease (SSNS).

Burosumab versus conventional therapy in children with X-linked hypophosphataemia: a randomised, active-controlled, open-label, phase 3 trial.

BACKGROUND: X-linked hypophosphataemia in children is characterised by elevated serum concentrations of fibroblast growth factor 23 (FGF23), hypophosphataemia, rickets, lower extremity bowing, and growth impairment. We compared the efficacy and safety of continuing conventional therapy, consisting of oral phosphate and active vitamin D, versus switching to burosumab, a fully human monoclonal antibody against FGF23, in paediatric X-linked hypophosphataemia. METHODS: In this randomised, active-controlled, open-label, phase 3 trial at 16 clinical sites, we enrolled children with X-linked hypophosphataemia aged 1-12 years. Key eligibility criteria were a total Thacher rickets severity score of at least 2·0, fasting serum phosphorus lower than 0·97 mmol/L (3·0 mg/dL), confirmed PHEX (phosphate-regulating endopeptidase homolog, X-linked) mutation or variant of unknown significance in the patient or a family member with appropriate X-linked dominant inheritance, and receipt of conventional therapy for at least 6 consecutive months for children younger than 3 years or at least 12 consecutive months for children older than 3 years. Eligible patients were randomly assigned (1:1) to receive either subcutaneous burosumab starting at 0·8 mg/kg every 2 weeks (burosumab group) or conventional therapy prescribed by investigators (conventional therapy group). Both interventions lasted 64 weeks. The primary endpoint was change in rickets severity at week 40, assessed by the Radiographic Global Impression of Change global score. All patients who received at least one dose of treatment were included in the primary and safety analyses. The trial is registered with ClinicalTrials.gov, number NCT02915705. FINDINGS: Recruitment took place between Aug 3, 2016, and May 8, 2017. Of 122 patients assessed, 61 were enrolled. Of these, 32 (18 girls, 14 boys) were randomly assigned to continue receiving conventional therapy and 29 (16 girls, 13 boys) to receive burosumab. For the primary endpoint at week 40, patients in the burosumab group had significantly greater improvement in Radiographic Global Impression of Change global score than did patients in the conventional therapy group (least squares mean +1·9 [SE 0·1] with burosumab vs +0·8 [0·1] with conventional therapy; difference 1·1, 95% CI 0·8-1·5; p<0·0001). Treatment-emergent adverse events considered possibly, probably, or definitely related to treatment by the investigator occurred more frequently with burosumab (17 [59%] of 29 patients in the burosumab group vs seven [22%] of 32 patients in the conventional therapy group). Three serious adverse events occurred in each group, all considered unrelated to treatment and resolved. INTERPRETATION: Significantly greater clinical improvements were shown in rickets severity, growth, and biochemistries among children with X-linked hypophosphataemia treated with burosumab compared with those continuing conventional therapy. FUNDING: Ultragenyx Pharmaceutical and Kyowa Kirin International.

Extraciliary roles of the ciliopathy protein JBTS17 in mitosis and neurogenesis.

OBJECTIVE: JBTS17 is a major gene mutated in ciliopathies such as Joubert syndrome and oral-facial-digital syndrome type VI. Most patients with loss of function mutations in JBTS17 exhibit cerebellar vermis hypoplasia and brainstem malformation. However, some patients with JBTS17 mutations show microcephaly and abnormal gyration. We examined potential roles of JBTS17 in neurogenesis to understand the pathological mechanism of JBTS17-related cortical abnormalities. METHODS: We examined subcellular localization and cell-cycle-dependent expression of JBTS17 proteins using anti-JBTS17 antibodies and JBTS17 expression vectors. We also performed knockdown experiments to determined roles of JBTS17 in human cells, and demonstrated mitotic functions of JBTS17 using immunostaining and live imaging. We examined the involvement of JBTS17 in cortical neurogenesis using a mouse in utero electroporation technique. RESULTS: We found that JBTS17 localizes to the kinetochore and the level of JBTS17 is regulated by cell-cycle-dependent proteolysis. Depletion of JBTS17 disrupts chromosome alignment and spindle pole orientation, resulting in mitotic delay. JBTS17 interacts with LIS1 and influences LIS1 localization. Depletion of Jbts17 in the developing mouse cortex interferes with the mitotic progression of neural progenitors and the migration of postmitotic neurons. INTERPRETATION: LIS1 is implicated in lissencephaly, but altered dosage of LIS1 has been also associated with microcephaly syndromes. Our results suggest that JBTS17 contributes to mitotic progression by interacting with LIS1, and abnormal mitosis is an underlying mechanism of the microcephaly phenotype in JBTS17-related ciliopathies. We propose that understanding extraciliary roles of ciliopathy proteins is important to elucidate pathological mechanisms underlying diverse ciliopathy phenotypes. ANN NEUROL 2019.

Rasburicase improves the outcome of acute kidney injury from typical hemolytic uremic syndrome.

BACKGROUND: Typical hemolytic uremic syndrome (HUS) causes acute kidney injury (AKI) and serious sequelae of chronic kidney disease (CKD) in some. Hyperuricemia is a common finding in typical HUS that may contribute to kidney damage. We explored whether aggressive management of hyperuricemia with rasburicase could improve outcomes in AKI patients with typical HUS. METHODS: We retrospectively analyzed medical records of children with typical HUS admitted to a tertiary center between 2005 and 2017. We compared clinical outcomes of hospitalization and 1-year post-discharge between those with rasburicase treatment (n = 13) and those without (controls, n = 29). RESULTS: With rasburicase treatment, hyperuricemia corrected more rapidly (median 36 vs. 120 h, p < 0.001), and hospital stays were shorter (median 9 vs. 12 days, p = 0.003) than in the controls. There was no difference in dialysis requirement. At 1-year post-discharge, the proportion of patients with impaired kidney function (estimated glomerular filtration rate < 90 mL/min/1.73 m2) was lower in the rasburicase group (7.7% vs. 41.4%, p = 0.036) than in the controls. Hypertension and proteinuria tended to be more common in the controls than in the rasburicase group. Collectively, long-term renal sequelae of impaired kidney function, proteinuria, or hypertension at a 1-year follow-up was less common in the rasburicase group than in the controls (7.7% vs. 62.1%; p = 0.001). CONCLUSIONS: Children with typical HUS treated with rasburicase had shorter hospital stays and less long-term sequelae at 1-year post-discharge than those who were not treated with rasburicase. These results support the use of rasburicase to prevent CKD in pediatric patients with typical HUS-associated AKI. Graphical Abstract.

Dyslipidemia in pediatric CKD patients: results from KNOW-PedCKD (KoreaN cohort study for Outcomes in patients With Pediatric CKD).

BACKGROUND: Pediatric as well as adult patients with chronic kidney disease (CKD) are susceptible to cardiovascular disease (CVD) events, which increase their mortality. Dyslipidemia is thought to be one of the most important contributing risk factors for developing CVD. This study aimed to evaluate the prevalence of dyslipidemia and assess clinical and laboratory risk factors associated with dyslipidemia in East Asian pediatric patients with CKD. METHODS: From April 2011 to April 2016, 469 patients with CKD aged < 20 years were enrolled in KNOW-PedCKD (the KoreaN cohort study for Outcomes in patients With Pediatric Chronic Kidney Disease); 356 patients were included in the final analysis. Using the baseline data of the cohort cross-sectionally, a multivariable logistic regression analysis was performed to assess the risk factors for dyslipidemia; a subanalysis for each lipid abnormality was also done. RESULTS: The prevalence of dyslipidemia was 61.5% (n = 219). For dyslipidemia, nephrotic range proteinuria and 25-hydroxyvitamin D deficiency significantly increased the adjusted odds ratio. In the subanalysis, glomerulonephropathy as the origin of CKD and nephrotic range proteinuria significantly increased the risks for high total cholesterol and high low-density lipoprotein cholesterol. Overweight or obese body mass index z-score, elevated proteinuria, hypocalcemia, and 1,25-dihydroxyvitamin D deficiency were significantly associated with low high-density lipoprotein cholesterol. Glomerular filtration rate stage 3b or higher and hyperphosphatemia significantly increased the risk for high triglycerides. CONCLUSIONS: Long-term data accumulation and prospective analysis are needed to clarify the relationship between CKD progression and dyslipidemia and to find additional risk factors for dyslipidemia.

Left-ventricular diastolic dysfunction in Korean children with chronic kidney disease: data from the KNOW-Ped CKD study.

BACKGROUND: Cardiovascular disease (CVD) is the most common cause of mortality in pediatric chronic kidney disease (CKD) patients. Left ventricular (LV) hypertrophy (LVH) is associated with LV diastolic dysfunction (LVDD) development and is used as an early marker of CVD in pediatric CKD. This study aimed to assess the prevalence and risk factors of LVDD and the association between LVH and LVDD in Korean pediatric CKD patients. METHODS: Data were collected using the baseline data of the Korean cohort study for outcome in patients with pediatric chronic kidney disease, a nationwide, 10-year, prospective, observational cohort study of pediatric CKD. A total of 244 patients were included in the final analysis. Two-dimensional echocardiography and tissue Doppler images were used to evaluate LVH and LVDD. LVH was defined as an LV mass index (LVMI) ≥38 g/m2.7 and LV-wall thickness z-score > 1.64. LVDD was defined as a mitral peak velocity of early filling to early diastolic mitral annular velocity (E/E') > 14. Univariate and multivariate logistic regression analyses were performed to evaluate risk factors of LVDD. RESULTS: In this study, the male-to-female ratio was 2.2 (168:76) and median age was 11.2 years. The average estimated glomerular filtration rate was 57.4 ml/min/1.73 m2, and no patients received renal replacement therapy. The mean value of LVMI and E/E' was 37.0 g/m2.7 and 7.4, respectively. The prevalence of LVH was 40.1 and 17.4% by LVMI ≥38 g/m2.7 and LV-wall thickness z-score, respectively. The prevalence of LVDD was 4.5%, and patients with LVH showed greater risk of LVDD (odds ratio 7.3, p = 0.012). In the univariate analysis, young age, low hemoglobin level, higher LVMI, and higher LV-wall thickness z-score were associated with LVDD. In the multivariate analysis, young age, low hemoglobin level, and higher LV-wall thickness z-score were independently associated with LVDD. CONCLUSION: This study shows that LVH patients have a greater risk of LVDD and that anemia is the only modifiable risk factor for LVDD in Korean pediatric CKD patients.

A Premature Baby with Severe Oligohydramnios and Hypotension: a Case Report of Renal Tubular Dysgenesis.

Renal tubular dysgenesis (RTD) is a rare fatal disorder in which there is poor development of proximal tubules, leading to oligohydramnios and the Potter sequences. RTD occurs secondary to renin-angiotensin system (RAS) blockade during the early stages of fetal development or due to autosomal recessive mutation of genes in the RAS pathway. A boy born at 33+1 weeks due to cord prolapse was found to be anuric and hypotensive. Pregnancy was complicated by severe oligohydramnios from gestational age 28+4 weeks. Abdominal sonography revealed diffuse globular enlargement of both kidneys with increased cortical parenchymal echogenicity. Infantogram showed a narrow thoracic cage and skull X-ray showed large fontanelles and wide sutures suggestive of ossification delay. Basal plasma renin activity was markedly elevated and angiotensin-converting enzyme was undetectable. Despite adequate use of medications, peritoneal dialysis, and respiratory support, he did not recover and expired on the 23rd day of life. At first, autosomal recessive polycystic kidney disease was suspected, but severe oligohydramnios along with refractory hypotension, anuria, skull ossification delay and high renin levels made RTD suspicious. ACE gene analysis revealed compound heterozygous pathogenic variations of c.1454.dupC in exon 9 and c.2141dupA in exon 14, confirming RTD. Based on our findings, we propose that, although rare, RTD should be suspected in patients with severe oligohydramnios and refractory hypotension.

Renal Syndromic Hearing Loss Is Common in Childhood-onset Chronic Kidney Disease.

BACKGROUND: Hearing loss (HL) in children may adversely affect their development. HL is more prevalent in patients with chronic kidney disease (CKD) than in the general population. This study evaluated the prevalence of HL and its underlying diseases in patients with childhood-onset in CKD. METHODS: In this retrospective study of a tertiary referral center, childhood-onset CKD patients (stage 2-5, age at onset of renal symptom < 18 years) were recruited. We referred to the "renal" syndromic HL as cases with genetic or syndromic diseases, or extra-renal anomalies in addition to HL and CKD. RESULTS: A total of 421 patients (male:female = 279:142) were reviewed according to the causes of CKD: congenital anomalies of the kidney and urinary tract (CAKUT; n = 184, 43.7%), glomerulopathies (GP; n = 105, 24.9%), cystic kidney diseases (CYST; n = 39, 9.3%), perinatal problems (PP; n = 29, 6.9%), and others (n = 64, 15.2%). HL was detected in 82 (19.5%) patients, including 51 (12.1%) patients with sensorineural hearing loss (SNHL), 30 (7.1%) with conductive hearing loss (CHL), and 1 patient with mixed HL. The prevalence of HL in each group was as follows: 16.8% in the CAKUT group, 28.6% in the GP group, 12.8% in the CYST group, 24.1% in the PP group, and 14.1% in the others group. HL was more common in higher CKD stages, especially CHL in end-stage renal disease. SNHL was more prevalent in CKD from GP. Of the 82 patients with HL, 50% had renal syndromic HL: 58.8% of SNHL and one-third of CHL were renal syndromic HL. CONCLUSION: One-fifth of the childhood-onset CKD had HL. Collectively, renal syndromic HL comprised half of the HL in this study. To improve the quality of life in patients with childhood-onset CKD, we suggest that HL should be considered, requiring surveillance, and if necessary, early intervention.

Erratum: Post-Transplant Lymphoproliferative Diseases in Pediatric Kidney Allograft Recipients with Epstein-Barr Virus Viremia.

This corrects the article on e203 in vol. 34, PMID: 31373185.

Acute Kidney Injury in Pediatric Cancer Patients.

OBJECTIVE: To analyze the incidence of acute kidney injury (AKI) in the first year after cancer diagnosis in children and to evaluate the short-term and long-term effects on renal function and proteinuria. STUDY DESIGN: Retrospective review of medical records was done on children who were diagnosed and treated for cancer at Seoul National University Hospital between 2004 and 2013. AKI was defined according to the Kidney Disease: Improving Global Outcomes criteria. Impaired renal function of estimated glomerular filtration rate less than 90 mL/minute/1.73 m2 and development of proteinuria of cancer survivors were also assessed. RESULTS: This study included 1868 patients who were diagnosed with cancer at a median age of 7.9 years. During the course of treatment, 983 patients (52.6%) developed 1864 episodes of AKI, and the cumulative incidence at 2 weeks, 3 months, and 1 year after diagnosis was 28.9%, 39.6%, and 53.6%, respectively. The 1-year cumulative incidence was the highest in patients with acute myeloid leukemias (88.4%). In all, 6.1% of patients had more than 4 episodes of AKI and 11.8% of patients had stage 3 AKI. Among the 1096 childhood cancer survivors, 22.6% were found to have impaired renal function. A greater number of AKI episodes (≥4 times) and nephrectomy were independent risk factors of impaired renal function. Also, 8.2% of the survivors developed proteinuria among 742 childhood cancer survivors. CONCLUSIONS: A large percentage of children with cancer experience AKI during the course of treatment, and AKI is associated with impaired long-term renal function.

Life-Threatening Extrarenal Manifestations in an Infant with Atypical Hemolytic Uremic Syndrome Caused by a Complement 3-Gene Mutation.

BACKGROUND: Atypical hemolytic uremic syndrome (aHUS) is a rare, life-threatening disease characterized by microangiopathic hemolytic anemia, thrombocytopenia, and renal impairment caused by uncontrolled activation of the complement system. About 20% of patients show extrarenal manifestations, with central nervous system involvement being the most frequent. We described the clinical course and management of aHUS in an infant, that was caused by a complement 3 (C3) gene mutation with severe extrarenal manifestations. CASE PRESENTATION: A 4-month-old girl visited our hospital for jaundice and petechiae. Laboratory tests revealed microangiopathic hemolytic anemia, thrombocytopenia, and hyperazotemia. She was diagnosed with aHUS with a C3 p.E1160K mutation. Daily fresh-frozen plasma (FFP) therapy was administered; however, she experienced the severe extrarenal manifestations of pulmonary hemorrhage and gastrointestinal bleeding. With aggressive treatment, supportive care, and daily FFP transfusion, the patient recovered and was discharged after 72 days of hospital stay, on a regular FFP transfusion. Four months after diagnosis, she was switched to eculizumab treatment. Twenty months have passed since then and she has been relapse-free until now. CONCLUSION: aHUS is rare but has a devastating course if not properly treated. Severe extrarenal manifestations, such as pulmonary hemorrhage and gastrointestinal bleeding, can develop in aHUS caused by a C3 mutation. In our case, long-term management with eculizumab resulted in relapse-free survival.

Low relapse rate of urinary tract infections from extended-spectrum beta-lactamase-producing bacteria in young children.

BACKGROUND: Extended-spectrum-beta-lactamase (ESBL)-producing bacteria are an increasingly important cause of urinary tract infections (UTIs) worldwide. We evaluated clinical characteristics and associated risk factors of UTIs in young children according to ESBL-producing status and relapse rates. METHODS: All urinary culture results in patients younger than 2 years old were assessed, and only children with febrile UTIs from gram-negative bacterial infections were reviewed. RESULTS: Of 845 episodes evaluated, 146 (17.3%) were caused by ESBL-positive bacteria. Significant differences were observed in previous UTIs, use of antibiotics or history of hospitalization within previous 3 months, and underlying urinary abnormalities between the ESBL UTI and non-ESBL UTI groups. After 2 weeks of treatment completion, UTI relapse occurred in 2.7% of children in the ESBL group and 1.1% of children in the non-ESBL group (P = 0.13). In the ESBL UTI group, relapse rate was not significantly different between patients treated with susceptible antibiotics and those treated with non-susceptible but clinically effective antibiotics. CONCLUSIONS: Previous history of UTI, antibiotic treatment, or hospitalization within previous 3 months and underlying disease are risk factors for ESBL UTI in children under 24 months of age. However, relapse rate was < 3% regardless of in vitro susceptibility of the treating antibiotics, as long as the antibiotics were clinically effective. We cautiously propose that we may continue the use of initial empirical antibiotics when a definite clinical response is observed, although further study is necessary to confirm the findings of this study.