Longitudinal progression trajectory of estimated glomerular filtration rate in children with chronic kidney disease: results from the KNOW-Ped CKD (KoreaN cohort study for Outcomes in patients With Pediatric Chronic Kidney Disease)

Background

The natural course of chronic kidney disease (CKD) progression in children varies according to their underlying conditions. This study aims to identify different patterns of subsequent decline in kidney function and investigate factors associated with different patterns of estimated glomerular filtration rate (eGFR) trajectories.

Methods

We analyzed data from the KNOW-Ped CKD (KoreaN cohort study for Outcomes in patients With Pediatric Chronic Kidney Disease), which is a longitudinal, prospective cohort study. A latent class linear mixed model was applied to identify the trajectory groups.

Results

In a total of 287 patients, the median baseline eGFR (mL/min/1.73 m2) was 63.3, and the median age was 11.5 years. The eGFR decline rate was -1.54 during a 6.0-year follow-up. The eGFR trajectory over time was classified into four groups. Classes 1 (n = 103) and 2 (n = 11) had a slightly reduced eGFR at enrollment with a stable trend (ΔeGFR, 0.2/year) and a rapid decline eGFR over time (ΔeGFR, -10.5/year), respectively. Class 3 had a normal eGFR (n = 16), and class 4 had a moderately reduced eGFR (n = 157); both these chasses showed a linear decline in eGFR over time (ΔeGFR, -4.1 and -2.4/year). In comparison with classes 1 and 2, after adjusting for age, causes of primary renal disease, and baseline eGFR, nephrotic-range proteinuria was associated with a rapid decline in eGFR (odds ratio, 8.13).

Conclusion

We identified four clinically relevant subgroups of kidney function trajectories in children with CKD. Most children showed a linear decline in eGFR; however, there are different patterns of eGFR trajectories.

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.

Corrigendum: Mineral bone disorder in children with chronic kidney disease: data from the KNOW-Ped CKD (Korean cohort study for outcome in patients with pediatric chronic kidney disease) study

[This corrects the article DOI: 10.3389/fped.2023.994979.].

Mineral bone disorder in children with chronic kidney disease: Data from the KNOW-Ped CKD (Korean cohort study for outcome in patients with pediatric chronic kidney disease) study

BACKGROUND

Children with chronic kidney disease (CKD) are at high risk of mineral bone disorder (MBD), which leads to fractures, growth retardation, and cardiovascular disease. We aimed to comprehensively understand the relationship between renal function and factors related to MBD and evaluate the prevalence and distribution characteristics of MBD, specifically among Korean patients from the KNOW-PedCKD cohort.

METHODS

From the baseline data of the KNOW-PedCKD cohort, we examined the prevalence and distribution of MBD in 431 Korean pediatric CKD patients, including the level of corrected total calcium, serum phosphate, serum alkaline phosphatase, serum intact parathyroid hormone (iPTH), fibroblast growth factor 23 (FGF-23), serum vitamin D, fractional excretion of phosphate (FEP), and bone densitometry Z-scores.

RESULTS

The median serum calcium level remained relatively normal regardless of the CKD stage. The levels of 1,25-dihydroxy vitamin D, urine calcium-to-creatinine ratio, and bone densitometry Z-score significantly decreased with advancing CKD stage, while those of serum phosphate, FGF-23, and FEP significantly increased with CKD stage. The prevalence of hyperphosphatemia (17.4%, 23.7%, and 41.2% from CKD stages 3b, 4, and 5, respectively) and hyperparathyroidism (37.3%, 57.4%, 55.3%, and 52.9% from CKD stages 3a, 3b, 4, and 5, respectively) significantly increased with the CKD stage. Prescriptions of medications, such as calcium supplements (39.1%, 42.1%, 82.4%), phosphate binders (39.1%, 43.4%, 82.4%), and active vitamin D (21.7%, 44.7%, and 64.7%) significantly increased with CKD stage 3b, 4, and 5, respectively.

CONCLUSIONS

The results demonstrated the prevalence and relationship of abnormal mineral metabolism and bone growth according to CKD stage in Korean pediatric CKD patients for the first time.

The compatibility of new blood pressure reference values for Korean children and adolescents with the US reference: the Korean Working Group of Pediatric Hypertension

Background

Childhood hypertension is associated with hypertension and metabolic syndrome in adulthood. Since the definition of childhood hypertension is based on the distribution of normative blood pressure (BP), a reference range is essential to create hypertension guidelines for children. We aimed to investigate the compatibility of the new Korean BP reference with the United States (US) BP reference based on the 2017 Clinical Practice Guideline.

Methods

We compared the new Korean reference BP values for children and adolescents aged 10 to 17 years with those in the 2017 Clinical Practice Guidelines. We also analyzed the differences in the prevalence of hypertension in Korean children and adolescents when reference value was applied. Considering Korean and US BP references together, linear trend lines were sought.

Results

Systolic BP (SBP) and diastolic BP (DBP) values in 95th percentiles showed no significant differences between the two BP references. Applying the two reference values, there was no significant difference in the prevalence of elevated BP and a combination of elevated BP and hypertension. Combining the Korean and US BP values and plotting them against age, approximate lines for the 90th and 95th SBP and DBP percentiles were observed.

Conclusions

The BP values of the new Korean BP reference were similar to those of the US BP reference; they were reliable and interchangeable.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40885-022-00200-x.

Characteristics of pediatric rhabdomyolysis and the associated risk factors for acute kidney injury: a retrospective multicenter study in Korea

Background

The clinical features of pediatric rhabdomyolysis differ from those of the adults with rhabdomyolysis; however, multicenter studies are lacking. This study aimed to investigate the characteristics of pediatric rhabdomyolysis and reveal the risk factors for acute kidney injury (AKI) in such cases.

Methods

This retrospective study analyzed the medical records of children and adolescents diagnosed with rhabdomyolysis at 23 hospitals in South Korea between January 2007 and December 2016.

Results

Among 880 patients, those aged 3 to 5 years old composed the largest subgroup (19.4%), and all age subgroups were predominantly male. The incidence of AKI was 11.3%. Neurological disorders (53.6%) and infection (39.0%) were the most common underlying disorder and cause of rhabdomyolysis, respectively. The median age at diagnosis in the AKI subgroup was older than that in the non-AKI subgroup (12.2 years vs. 8.0 years). There were no significant differences in body mass index, myalgia, dark-colored urine, or the number of causal factors between the two AKI-status subgroups. The multivariate logistic regression model indicated that the following factors were independently associated with AKI: multiorgan failure, presence of an underlying disorder, strong positive urine occult blood, increased aspartate aminotransferase and uric acid levels, and reduced calcium levels.

Conclusions

Our study revealed characteristic clinical and laboratory features of rhabdomyolysis in a Korean pediatric population and highlighted the risk factors for AKI in these cases. Our findings will contribute to a greater understanding of pediatric rhabdomyolysis and may enable early intervention against rhabdomyolysis-induced AKI.

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.

Mortality in Children Treated With Maintenance Peritoneal Dialysis: Findings From the International Pediatric Peritoneal Dialysis Network Registry

RATIONALE & OBJECTIVE

Research on pediatric kidney replacement therapy (KRT) has primarily focused on Europe and North America. In this study, we describe the mortality risk of children treated with maintenance peritoneal dialysis (MPD) in different parts of the world and characterize the associated demographic and macroeconomic factors.

STUDY DESIGN

Prospective cohort study.

SETTING & PARTICIPANTS

Patients younger than 19 years at inclusion into the International Pediatric Peritoneal Dialysis Network registry, who initiated MPD between 1996 and 2017.

EXPOSURE

Region as primary exposure (Asia, Western Europe, Eastern Europe, Latin America, North America, and Oceania). Other demographic, clinical, and macroeconomic (4 income groups based on gross national income) factors also were studied.

OUTCOME

All-cause MPD mortality.

ANALYTICAL APPROACH

Patients were observed for 3 years, and the mortality rates in different regions and income groups were calculated. Cause-specific hazards models with random effects were fit to calculate the proportional change in variance for factors that could explain variation in mortality rates.

RESULTS

A total of 2,956 patients with a median age of 7.8 years at the start of KRT were included. After 3 years, the overall probability of death was 5%, ranging from 2% in North America to 9% in Eastern Europe. Mortality rates were higher in low-income countries than in high-income countries. Income category explained 50.1% of the variance in mortality risk between regions. Other explanatory factors included peritoneal dialysis modality at start (22.5%) and body mass index (11.1%).

LIMITATIONS

The interpretation of interregional survival differences as found in this study may be hampered by selection bias.

CONCLUSIONS

This study shows that the overall 3-year patient survival on pediatric MPD is high, and that country income is associated with patient survival.

Case of catastrophic antiphospholipid syndrome presenting as neuroretinitis and vaso-occlusive retinopathy

BACKGROUND

Ocular involvement in catastrophic antiphospholipid syndrome (CAPS), a rare, life-threatening form of antiphospholipid syndrome (APS) that results in multiorgan failure and a high mortality rate, has rarely been reported.

CASE PRESENTATION

A 15-year-old girl presented with sudden vision blurring in both eyes. She had marked optic disc swelling and macular exudates in the right eye and intra-arterial white plaques, a few retinal blot hemorrhages, and a white ischemic retina in the left eye. Systemic examination revealed she had acute kidney injury with thrombotic microangiopathy (TMA), multiple cerebral infarcts, valvular dysfunction, and a high titer of triple aPL. Thus, she was diagnosed with CAPS involving the brain, eyes, heart, and kidneys. Plasma exchange and the administration of glucocorticoids, immunoglobulin, warfarin, and rituximab brought a sustained recovery of the TMA, visual symptoms, and echocardiographic findings.

CONCLUSIONS

Ocular involvement of both vaso-occlusive retinopathy, an APS-related thrombotic microangiopathy, and neuroretinitis, a non-thrombotic microangiopathy, can occur as an initial presentation of CAPS.

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/m^2.7 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/m^2.7 and 7.4, respectively. The prevalence of LVH was 40.1 and 17.4% by LVMI ≥38 g/m^2.7 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.

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.

Remission of Proteinuria May Protect against Progression to Chronic Kidney Disease in Pediatric-Onset IgA Nephropathy

Immunoglobulin A nephropathy (IgAN) is one of the most common primary glomerulopathies diagnosed in children and adolescents. This study aimed to evaluate the clinical features in and outcomes of pediatric IgAN over the last 30 years. Patients who were diagnosed before age of 18 at 20 centers in Korea were evaluated retrospectively. Of the 1154 patients (768 males, 386 females) with a median follow-up of 5 years, 5.6% (n = 65) progressed to stage 3–5 chronic kidney disease (CKD). The 10- and 20-year CKD-free survival rates were 91.2% and 75.6%, respectively. Outcomes did not differ when comparing those in Korea who were diagnosed prior to versus after the year 2000. On multivariate analysis, combined asymptomatic hematuria and proteinuria as presenting symptoms and decreased renal function at the time of biopsy were associated with progression to CKD, while remission of proteinuria was negatively associated with this outcome. Patients who presented with gross hematuria or nephrotic syndrome tended toward positive outcomes, especially if they ultimately achieved remission. While remission of proteinuria might imply that the disease is inherently less aggressive, it also can be achieved by management. Therefore, more aggressive management might be required for pediatric-onset IgAN.

Genetic Study in Korean Pediatric Patients with Steroid-Resistant Nephrotic Syndrome or Focal Segmental Glomerulosclerosis

Steroid-resistant nephrotic syndrome (SRNS) is one of the major causes of end-stage renal disease (ESRD) in childhood and is mostly associated with focal segmental glomerulosclerosis (FSGS). More than 50 monogenic causes of SRNS or FSGS have been identified. Recently, the mutation detection rate in pediatric patients with SRNS has been reported to be approximately 30%. In this study, genotype-phenotype correlations in a cohort of 291 Korean pediatric patients with SRNS/FSGS were analyzed. The overall mutation detection rate was 43.6% (127 of 291 patients). WT1 was the most common causative gene (23.6%), followed by COQ6 (8.7%), NPHS1 (8.7%), NUP107 (7.1%), and COQ8B (6.3%). Mutations in COQ6, NUP107, and COQ8B were more frequently detected, and mutations in NPHS2 were less commonly detected in this cohort than in study cohorts from Western countries. The mutation detection rate was higher in patients with congenital onset, those who presented with proteinuria or chronic kidney disease/ESRD, and those who did not receive steroid treatment. Genetic diagnosis in patients with SRNS provides not only definitive diagnosis but also valuable information for decisions on treatment policy and prediction of prognosis. Therefore, further genotype-phenotype correlation studies are required.

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 (P_meta=6.71E-28, OR=1.88) and TNFSF15 (P_meta=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).

Mechanism of Chronic Kidney Disease Progression and Novel Biomarkers: A Metabolomic Analysis of Experimental Glomerulonephritis

While a complex network of cellular and molecular events is known to be involved in the pathophysiological mechanism of chronic kidney disease (CKD), the divergence point between reversal and progression and the event that triggers CKD progression are still unknown. To understand the different mechanisms between reversible and irreversible kidney disease and to search for urinary biomarkers that can predict prognosis, a metabolomic analysis was applied to compare acute and chronic experimental glomerulonephritis (GN) models. Four metabolites, namely, epoxyoctadecenoic acid (EpOME), epoxyeicosatetraenoic acid (EpETE), α-linolenic acid (ALA), and hydroxyretinoic acid, were identified as predictive markers after comparing the chronic nephritis model with acute nephritis and control groups (false discovery rate adjusted p-value (q-value) < 0.05). Renal mRNA expression of cytochrome P450 and epoxide hydrolase was also identified as being involved in the production of epoxide metabolites from these polyunsaturated fatty acids (p < 0.05). These results suggested that the progression of chronic kidney disease is associated with abnormally activated epoxide hydrolase, leading to an increase in EpOME and EpETE as pro-inflammatory eicosanoids.

Targeted Exome Sequencing Provided Comprehensive Genetic Diagnosis of Congenital Anomalies of the Kidney and Urinary Tract

Congenital anomalies of the kidney and urinary tract (CAKUT) are the most common cause of chronic kidney disease in children. The search for genetic causes of CAKUT has led to genetic diagnosis in approximately 5-20 % of CAKUT patients from Western countries. In this study, genetic causes of CAKUT in Korean children were sought using targeted exome sequencing (TES) of 60 genes reported to cause CAKUT in human or murine models. We identified genetic causes in 13.8% of the 94 recruited patients. Pathogenic single nucleotide variants of five known disease-causing genes, HNF1B, PAX2, EYA1, UPK3A, and FRAS1 were found in 7 cases. Pathogenic copy number variations of 6 patients were found in HNF1B, EYA1, and CHD1L. Genetic abnormality types did not significantly differ according to CAKUT phenotypes. Patients with pathogenic variants of targeted genes had syndromic features more frequently than those without (p < 0.001). This is the first genetic analysis study of Korean patients with CAKUT. Only one-seventh of patients were found to have pathogenic mutations in known CAKUT-related genes, indicating that there are more CAKUT-causing genes or environmental factors to discover.

High prevalence of systemic hypertension in pediatric patients with moyamoya disease years after surgical treatment

OBJECTIVE

Although an association between moyamoya disease (MMD) and renovascular hypertension has been acknowledged, the literature on systemic hypertension without renal artery stenosis among patients with MMD is scarce. The authors aimed to evaluate the prevalence and risk factors of hypertension using data from MMD patients who visited an outpatient clinic of a pediatric neurosurgical department in 2016.

METHODS

The authors evaluated the blood pressure (BP) of pediatric MMD patients at their postsurgical appointment following the American Academy of Pediatrics clinical practice guideline on high BP, in which hypertension was defined as BP measurements higher than the value of age-, sex-, and height-specific 95th percentile of the general population from at least 3 separate visits. Growth of patients was determined using 2017 Korean National Growth Charts for children and adolescents. The cutoff value of the 95th percentile of BP was determined by referring to normative BP tables of Korean children and adolescents. A logistic regression model was used to assess the associations between patients' clinical characteristics and prevalent hypertension.

RESULTS

In total, 131 surgically treated pediatric MMD patients were included, of whom 38.9% were male and the median age at diagnosis was 8.0 years (range 1.2-15.0 years). The definition of hypertension was met in 38 patients, with a prevalence of 29.0% (95% CI 21.2%-36.8%). A tendency was observed for a higher prevalence of hypertension in male patients (31.4%), in patients with posterior cerebral artery (PCA) involvement (47.8%), and in cases in which infarction was shown on initial MRI (37.3%). Age at diagnosis (adjusted OR [aOR] 0.82, 95% CI 0.70-0.97), PCA involvement (aOR 3.81, 95% CI 1.29-11.23), body mass index (aOR 1.30, 95% CI 1.13-1.51), and years of follow-up since surgery (aOR 0.80, 95% CI 0.68-0.94) were related to systemic hypertension.

CONCLUSIONS

A high prevalence of hypertension was demonstrated in pediatric MMD patients. Therefore, adequate attention should be paid to reduce BP and prevent subsequent events.

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.

Mental health and psychosocial adjustment in pediatric chronic kidney disease derived from the KNOW-Ped CKD study

BACKGROUND

Psychosocial development of pediatric chronic kidney disease (CKD) patients is substantially affected due to growth retardation, frequent school absences, and difficulties engaging in normal peer relationship activities. While many studies focus on specific issues such as depression, anxiety, or neurocognitive function, few evaluate prevalence of various types of mental health and psychosocial adjustment problems among children with CKD. This study aimed to investigate these within the KoreaN cohort study for Outcomes in patients With Pediatric Chronic Kidney Disease (KNOW-Ped CKD).

METHODS

One hundred sixty-six subjects who completed the Korean-Child Behavioral Checklist (K-CBCL) were included. The clinical group comprised subjects with scores indicating psychosocial adjustment or mental health problems using the T scores for the 14 subscales of the K-CBCL. We analyzed associations between mental health or adjustment problems in pediatric CKD and each variable.

RESULTS

Mean age was 11.1 (± 3.9) years, number of males was 117 (70.5%), and 20.5% and 22.3% of children had significant mental health problems and psychosocial adjustment problems, respectively. Overall, 33.1% were assigned to the clinical group, and exhibited short stature and higher rates of preterm birth history compared to the non-clinical group. Subjects with adjustment problems had higher comorbidities such as CNS disease, developmental delay, cardiovascular disease, and multi-organ involvement. Logistic regression analysis revealed preterm birth and developmental delay correlated highly with clinical group.

CONCLUSIONS

A significant proportion of children and adolescents with CKD experience mental health and adjustment problems. In particular, patients with developmental delay or preterm birth history require screening and targeted follow-up.

Acute kidney injury associated with Yersinia pseudotuberculosis infection: Forgotten but not gone

Background

Yersinia pseudotuberculosis is known to cause fever, gastroenteritis, or acute kidney injury (AKI). There have been several Y. pseudotuberculosis infection outbreaks to date associated with ingestion of contaminated food or unsterile water. While this disease was considered to have practically been eradicated with the improvement in public health, we encountered several cases of AKI associated with Yersinia infection.

Methods

We retrospectively collected data from medical records of patients with suspected Y. pseudotuberculosis infection who visited Seoul National University Children's Hospital in 2017.

Results

There were nine suspected cases of Yersinia infection (six males and three females; age range 2.99-12.18 years). Among them, five cases occurred in May, and seven patients were residing in the metropolitan Seoul area. Three patients had history of drinking mountain water. Every patient first presented with fever for a median of 13 days, followed by gastrointestinal symptoms and oliguria. Imaging studies revealed mesenteric lymphadenitis, terminal ileum wall thickening, and increased renal parenchymal echogenicity. Creatinine levels increased to 5.72 ± 2.18 mg/dL. Urinalysis revealed sterile pyuria, proteinuria, and glycosuria. Oliguria continued for 4 to 17 days, and two patients required dialysis; however, all of them recovered from AKI. Mucocutaneous manifestations developed later. In the diagnostic work-up, Yersinia was isolated from the stool culture in one patient. Anti-Yersinia immunoglobulin (Ig) A and IgG were positive in 6 patients.

Conclusion

Y. pseudotuberculosis infection is an infrequent cause of interstitial nephritis presenting with AKI. When a patient presents with fever, gastroenteritis, and AKI not resolving despite hydration, the clinician should suspect Y. pseudotuberculosis infection.

Higher Incidence of BK Virus Nephropathy in Pediatric Kidney Allograft Recipients with Alport Syndrome

A retrospective review was performed to assess the risk factors and outcomes of BK virus infection and nephropathy (BKVN), an early complication in pediatric kidney allograft recipients. The study investigated the incidence, risk factors, and clinical outcomes of BK viremia and BKVN in a Korean population of pediatric patients who received renal transplantation from 2001–2015 at the Seoul National University Hospital. BKVN was defined as biopsy-proven BKVN or plasma BK viral loads >10,000 copies/mL for >3 weeks. BK viremia was defined as a BK viral load >100 copies/mL in blood. Among 168 patients assessed for BK virus status, 30 patients (17.9%) tested positive for BK viremia at a median of 12.6 months after transplantation. BKVN was diagnosed in six patients (3.6%) at a median of 13.4 months after transplantation. Three of the six BKVN patients had Alport syndrome (p = 0.003), despite this disease comprising only 6% of the study population. Every patient with BK viremia and Alport syndrome developed BKVN, while only 11.1% of patients with BK viremia progressed to BKVN in the absence of Alport syndrome. Multivariate analysis revealed that Alport syndrome was associated with BKVN development (hazard ratio 13.2, p = 0.002). BKVN treatment included the reduction of immunosuppression, leflunomide, and intravenous immunoglobulin. No allografts were lost in the two years following the diagnosis of BKVN. In summary, the incidence of BKVN in pediatric kidney allograft recipients was similar to findings in previous reports, but was higher in patients with underlying Alport syndrome.

Anemia and Iron Deficiency in Children with Chronic Kidney Disease (CKD): Data from the Know-Ped CKD Study

Children with chronic kidney disease (CKD) are at high risk of anemia, an important risk factor for cardiovascular disease and poor quality of life. The present study used baseline data from the Korean cohort study for Outcome in patients With Pediatric Chronic Kidney Disease (KNOW-PedCKD). A Total of 437 patients was included in the analyses excluding missing data. The characteristics of patients with and without anemia and those of patients with and without iron deficiency were compared. Logistic regression analysis and Pearson correlation were conducted to evaluate associated risk factors and correlations in children with CKD. Anemia in children with CKD was associated with older age, low body weight and body mass index (BMI) z-score, birth age, preceding glomerulonephritis, decreased estimated glomerular filtration rate (eGFR), low levels of serum albumin and calcium, high levels of serum intact parathyroid hormone (iPTH), and serum phosphorus. Anemia was correlated positively with changes in the BMI z-score, body weight, and serum albumin and cholesterol levels, but correlated negatively with serum calcium, iPTH, ferritin levels, and transferrin saturation. Iron deficiency in children with CKD was associated with young age, low hemoglobin and serum ferritin levels, high BMI z-scores, and low levels of serum iPTH. This is the first nationwide cohort study of anemia in Korean children with CKD and the first prospective pediatric CKD cohort study in Asia. The study results demonstrated that anemia and iron deficiency are affected by various factors, including age, BMI, and levels of serum iPTH. To improve the retrospective outcome of affected children, it is important to understand the effect of each of these factors and to attempt an early intervention to prevent anemia and iron deficiency by regular measurement of these parameters in children at risk.

Efficacy and safety of rituximab in childhood-onset, difficult-to-treat nephrotic syndrome: A multicenter open-label trial in Korea

BACKGROUND

The anti-CD20 monoclonal antibody rituximab (RTX) has been proposed as a rescue therapy for difficult-to-treat nephrotic syndrome (NS). We conducted a clinical trial to evaluate the efficacy and safety of RTX in children with difficult-to-treat NS dependent on or resistant to steroids and calcineurin inhibitors (CNIs).

METHODS

A multicenter open-label trial was performed at 8 major pediatric nephrology centers in Korea. The investigation consisted of a randomized controlled trial for steroid- and CNI-dependent NS (DDNS; randomization into the RTX group and the control group, at a ratio of 2:1) and a single-arm study of steroid and CNI-resistant NS (DRNS). DDNS patients in the RTX group and DRNS patients received a single dose of intravenous RTX (375 mg/m of body surface area) for B-cell depletion. A second RTX dose was administered at week 2 if the first dose failed to achieve depletion of CD19(+) cells. The primary endpoint was rate of maintaining remission at 6 months after treatment for DDNS and rate of remission achievement for DRNS.

RESULTS

Sixty-one children with DDNS were enrolled while in remission and randomized to the control group (21 patients) or the RTX group (40 patients). At 6 months after treatment, the remission rates were 74.3% in the RTX group and 31.3% in the control group (P = .003). The mean duration of remission maintenance was significantly higher in the RTX group than in the control group (9.0 vs 2.9 months, P = .004). Of the 23 patients with DRNS enrolled in the single-arm study and treated with RTX, 9 (39.1%) achieved partial or complete remission within 6 months. Depletion of B cells occurred in all patients with RTX therapy. Thirty patients (50.8% of 59 patients analyzed) experienced mild and transient infusion reaction during RTX administration, and most adverse events were mild.

CONCLUSIONS

RTX administration was safe and effective in patients with difficult-to-treat NS. One or 2 doses of RTX may be sufficient to deplete B cells and achieve better control of pediatric NS.

Reninoma: a rare cause of curable hypertension

The most common type of refractory hypertension found in children is secondary hypertension, which is a potentially curable disease. Reninoma, a renin-secreting juxtaglomerular cell tumor, is a rare cause of severe hypertension that is usually diagnosed in adolescents and young adults. Surgical resection of the tumor completely cures the hypertension of patients with reninoma. The typical clinical presentation of reninoma includes hypokalemia, metabolic alkalosis, and features secondary to the increased activation of the renin-angiotensin system without renal artery stenosis. We report a case of reninoma in a female adolescent with a typical clinical presentation, in which surgical removal of the tumor completely cured hypertension. We discuss here the clinical features, imaging studies, and immunohistochemical examination of the tumor used to establish the diagnosis of reninoma and for the management of the condition.

Cutaneous Skeletal Hypophosphatemia Syndrome in Association with a Mosaic HRAS Mutation

Recent molecular genetic studies have revealed that Schimmelpenning-Feuerstein-Mims syndrome (SFMS), which presents as sebaceous nevi, is a mosaic RASopathy caused by postzygotic somatic activating mutations in HRAS, NRAS, or KRAS Some patients with SFMS also have hypophosphatemic rickets, called cutaneous skeletal hypophosphatemia syndrome (CSHS). We here report a pediatric case of biopsy-proven CSHS with mosaic mutation in the HRAS gene. A girl who showed extensive nevus sebaceous since birth had suffered progressive lower extremity deformity since the age of 5 years. We found hypophosphatemic rickets in laboratory and radiological studies. From the molecular study with skin tissue with nevus sebaceous, we identified a heterozygous mutation, c.182A>G (p.Gln61Arg), in exon 3 of HRAS by Sanger sequencing. However, we did not find this mutation in the peripheral blood and unaffected tissue, which demonstrated mosaic distribution of the mutation throughout the body. Given the rarity of the previous genetically proven CSHS cases, accumulation of more cases is needed to establish the role of Ras activation in skeletal manifestations in CSHS, which is likely due to excessive production of fibroblast growth factor 23.

Loss of podocalyxin causes a novel syndromic type of congenital nephrotic syndrome

Many cellular structures directly imply specific biological functions. For example, normal slit diaphragm structures that extend from podocyte foot processes ensure the filtering function of renal glomeruli. These slits are covered by a number of surface proteins, such as nephrin, podocin, podocalyxin and CD2AP. Here we report a human patient presenting with congenital nephrotic syndrome, omphalocele and microcoria due to two loss-of-function mutations in PODXL, which encodes podocalyxin, inherited from each parent. This set of symptoms strikingly mimics previously reported mouse Podxl^−/− embryos, emphasizing the essential function of PODXL in mammalian kidney development and highlighting this patient as a human PODXL-null model. The results underscore the utility of current genomics approaches to provide insights into the genetic mechanisms of human disease traits through molecular diagnosis.

Delayed transplantation may affect intellectual ability in children

BACKGROUND

Decline in neurocognitive function is a reported complication in children with chronic illness. Concerns have been increasing that exposure to a major surgery or trauma may negatively affect cognitive performance in children. This study evaluated cognitive function in 43 Korean children who received organ transplantation (Tx), and sought to identify associated clinical factors.

METHODS

Pediatric recipients of kidney (KT) or liver Tx (LT) from 1999 to 2011 were recruited for cognitive tests. Cognitive function was evaluated using intelligence quotient (IQ), social quotient (SQ), and Continuous Performance Test using Advanced Test for Attention scores, which reflect attention ability. Intellectual delay was graded as intellectual disability (ID; IQ <70) or low intelligence (LI; IQ<85). Diagnosis for attention-deficit-hyperactivity disorder (ADHD) was made by pediatric psychiatrists.

RESULTS

The subjects consisted of 43 pediatric recipients of 28 LT and 15 KT. There were 20 boys (46.5%). Median age was 3.1 years (range, 0.5-15.3 years) at Tx. Median age at cognitive evaluation was 12.9 years (range, 3.4-18.4 years). Median pre-Tx duration of illness was 1.6 years (range, 0-13.5 years). The prevalence of ID, LI, and ADHD was 11.6%, 32.5%, and 32.5%, respectively. On multivariate analysis, longer pre-Tx duration of illness was a significant factor for LI (OR, 1.263; 95%CI: 1.033-1.544, P = 0.023).

CONCLUSION

Longer pre-Tx duration may negatively affect intellectual ability in Korean children. Pre-Tx duration was more significant than the age at Tx or total disease duration per se. Early Tx may be beneficial for cognitive function in children.

Long-term repeated rituximab treatment for childhood steroid-dependent nephrotic syndrome

BACKGROUND

Rituximab (RTX) can be used as a rescue therapy for steroid-dependent nephrotic syndrome (SDNS). However, the efficacy and safety of long-term, repeated use of RTX are not established. This study was conducted to assess the efficacy and safety of long-term, repeated RTX treatment in children.

METHODS

Eighteen consecutive child patients with SDNS who were treated with three or more cycles of RTX for one year or longer were recruited, and their medical records were retrospectively reviewed.

RESULTS

The patients were followed for 4.7 ± 1.9 years and received 5.2 ± 2.3 cycles of RTX over 2.8 ± 1.1 years. Approximately 70% of the additional RTX cycles were administered due to recovery of B-cells without relapse. The relapse rate decreased from 3.4 ± 2.0 per year initially to 0.4 ± 0.8 per year at the third year after RTX treatment. Approximately 10% of the RTX infusions were accompanied by mild infusion reactions. Eight patients showed sustained remission without any oral medication after the last cycle of RTX, while 10 patients had one or more episodes of relapse after the last cycle of RTX. The relapse rate in the latter group decreased from 2.8 ± 1.5 per year before RTX treatment to 1.3 ± 0.8 per year after cessation of RTX treatment. No significant differences in clinical parameters were found between the two groups.

CONCLUSION

This retrospective study showed that pre-emptive and long-term, repeated RTX treatment is relatively effective and safe in children with SDNS. However, well-designed prospective studies are needed to confirm these findings.

Influence of the Method of Definition on the Prevalence of Left-Ventricular Hypertrophy in Children with Chronic Kidney Disease: Data from the Know-Ped CKD Study

BACKGROUND/AIMS

Children with chronic kidney disease (CKD) have a high risk of cardiovascular disease. Left-ventricular (LV) hypertrophy (LVH) is an early marker of cardiovascular disease in pediatric CKD, and the prevalence of LVH in pediatric CKD is approximately 20-30% in pre-dialysis CKD patients. However, there is no consensus on the ideal method of defining LVH in pediatric CKD patients. Previous studies have typically used the LV mass index (LVMI), which is calculated as LV mass in grams divided by height in meters to the 2.7th power ≥ 38 g/m2.7, to diagnose LVH in children with CKD. Recently, age-specific reference values for LVMI ≥ 95th percentile and LV wall-thickness z-score > 1.64 in children were addressed. The aim of this study was to assess the prevalence and contributing factors of LVH in pediatric CKD patients according to each measurement and evaluate the concordance between each measurement.

METHODS

We used the baseline data of the KoreaN cohort study for Outcome in patients With Pediatric Chronic Kidney Disease (KNOW-Ped CKD), which is a nationwide, 10-year, prospective, observational cohort study of pediatric CKD. A total of 469 patients were enrolled, and 458 patients were included in the final analysis. Univariate and multiple logistic regression analysis were performed to evaluate the association of the variables with LVH. Kappa statistics were used to analyze the concordance.

RESULTS

According to an LVH diagnosis of LVMI ≥ 38 g/m2.7, 188 patients (41.0%) were diagnosed with LVH, and the prevalence of LVH was high in younger patients (< 2 years of age). Using the age-specific reference values, 116 patients (25.3%) were diagnosed with LVH, and there was no difference in the prevalence of LVH according to age. Thirty-one patients (6.8%) were diagnosed with LVH using an LV wall-thickness z-score > 1.64. There is poor concordance between the diagnosis of LVH using the LV wall-thickness z-score and the LVMI method.

CONCLUSIONS

The results of this study show that there is poor concordance between the diagnosis of LVH using the wall-thickness z-score and the LVMI2.7 criteria. Further investigation is needed to estimate the correlation between LVH and cardiac dysfunction and to find a better method for defining LVH in the pediatric CKD cohort and thereby predicting cardiac dysfunction.

Posttransplantation lymphoproliferative disorder after pediatric solid organ transplantation: experiences of 20 years in a single center

PURPOSE

To evaluate the clinical spectrum of posttransplantation lymphoproliferative disorder (PTLD) after solid organ transplantation (SOT) in children.

METHODS

We retrospectively reviewed the medical records of 18 patients with PTLD who underwent liver (LT) or kidney transplantation (KT) between January 1995 and December 2014 in Seoul National University Children's Hospital.

RESULTS

Eighteen patients (3.9% of pediatric SOTs; LT:KT, 11:7; male to female, 9:9) were diagnosed as having PTLD over the last 2 decades (4.8% for LT and 2.9% for KT). PTLD usually presented with fever or gastrointestinal symptoms in a median period of 7 months after SOT. Eight cases had malignant lesions, and all the patients except one had evidence of Epstein-Barr virus (EBV) involvement, assessed by using in situ hybridization of tumor tissue or EBV viral load quantitation of blood. Remission was achieved in all patients with reduction of immunosuppression and/or rituximab therapy or chemotherapy, although 1 patient had allograft kidney loss and another died from complications of chemotherapy. The first case of PTLD was encountered after the introduction of tacrolimus for pediatric SOT in 2003. The recent increase in PTLD incidence in KT coincided with modification of clinical practice since 2012 to increase the tacrolimus trough level.

CONCLUSION

While the outcome was favorable in that all patients achieved complete remission, some patients still had allograft loss or mortality. To prevent PTLD and improve its outcome, monitoring for EBV infection is essential, which would lead to appropriate modification of immunosuppression and enhanced surveillance for PTLD.

Three cases of Gordon syndrome with dominant KLHL3 mutations

BACKGROUND

Gordon syndrome (GS) is a rare form of monogenic hypertension characterized by low renin hypertension, hyperkalemia, hyperchloremic metabolic acidosis, and normal glomerular filtration rate. To date, four genes causing GS have been identified as: WNK1, WNK4, CUL3, and KLHL3.

CASE PRESENTATION

We report three cases of GS in two families. All patients presented with typical clinical features of GS and had a known dominant KLHL3 mutation. Oral thiazide treatment with low salt diet resulted in normalization of blood pressure and serum electrolytes in all three cases.

CONCLUSIONS

GS should be considered in patients with low renin hypertension and hyperkalemia. Although it is a rare disease, the correct diagnosis of GS is clinically important, as it can easily be treated with a low sodium diet or thiazides. In addition, family studies can identify individuals with undiagnosed GS as all mutations causing this disease, except for some recessive KLHL3 mutations, are dominant mutations.

Markers of disease and steroid responsiveness in paediatric idiopathic nephrotic syndrome: Whole-transcriptome sequencing of peripheral blood mononuclear cells

Objective

To identify markers of disease and steroid responsiveness in paediatric idiopathic nephrotic syndrome.

Methods

Whole-transcriptome sequencing was performed of peripheral blood mononuclear cells (PBMCs) from patients with NS. Differentially expressed genes (DEGs) were identified in patients with active NS vs those in remission, and those with steroid-sensitive NS (SSNS) vs steroid-resistant NS (SRNS).

Results

A total of 1065 DEGs were identified in patients with NS (n = 10) vs those in remission (n = 9). These DEGs correlated with cytokine and/or immune system signalling and the extracellular matrix. Comparisons between SSNS (n = 6) and SRNS (n = 4) identified 1890 DEGs. These markers of steroid responsiveness were enriched with genes related to the cell cycle, targets of microRNAs, and genes related to cytokines.

Conclusions

Meaningful DEGs were identified. Additional studies with larger numbers of patients will provide more comprehensive data.

Genotype-phenotype analysis of pediatric patients with WT1 glomerulopathy

BACKGROUND

WT1 is one of the genes commonly reported as mutated in children with steroid-resistant nephrotic syndrome (SRNS). We analyzed genotype-phenotype correlations in pediatric SRNS patients with WT1 mutations.

METHODS

From 2001 to 2015, WT1 mutations were detected in 21 out of 354 children with SRNS by genetic screening (5.9 %). The patients were grouped into missense (n = 11) and KTS splicing (n = 10) mutation groups.

RESULTS

Nine (82 %) patients with missense mutations presented with congenital/infantile nephrotic syndrome, while 8 (80 %) with KTS splicing mutations presented with childhood-onset SRNS. Progression to end-stage renal disease (ESRD) was noted in all patients with missense mutations (median age, 2.6 months; interquartile range [IQR], 0.8 months to 1.7 years) and in 5 patients with KTS splicing mutations (median, 9.3 years; IQR, 3.3-16.5 years). Disorders of sexual development (DSDs) were noted in all 12 patients with a 46, XY karyotype and in only 1 of the 8 patients with a 46, XX karyotype. One patient developed a Wilms tumor and another developed gonadoblastoma. Three patients had a diaphragmatic defect or hernia.

CONCLUSIONS

WT1 mutations manifest as a wide spectrum of renal and extra-renal phenotypes. Genetic diagnosis is essential for overall management and to predict the genotype-specific risk of DSDs and the development of malignancies.

A familial case of Blau syndrome caused by a novel NOD2 genetic mutation

Blau syndrome (BS) is a rare autosomal dominant, inflammatory syndrome that is characterized by the clinical triad of granulomatous dermatitis, symmetric arthritis, and recurrent uveitis. Mutations in the nucleotide oligomerization domain 2 (NOD2) gene are responsible for causing BS. To date, up to 30 Blau-associated genetic mutations have been identified within this gene. We report a novel NOD2 genetic mutation that causes BS. A girl, aged 8 years, and her brother, aged 10 years, developed erythematous skin rashes and uveitis. The computed tomography angiogram of the younger sister showed features of midaortic dysplastic syndrome. The brother had more prominent joint involvement than the sister. Their father (38 years) was also affected by uveitis; however, only minimal skin involvement was observed in his case. The paternal aunt (39 years) and her daughter (13 years) were previously diagnosed with sarcoidosis. Mutational analysis revealed a novel c.1439 A>G mutation in the NOD2 gene in both siblings. The novel c.1439 A>G mutation in the NOD2 gene was found in a familial case of BS. Although BS is rare, it should always be considered in patients presenting with sarcoidosis-like features at a young age. Early diagnosis of BS and prompt multisystem workup including the eyes and joints can improve the patient's outcome.

A nonsense PAX6 mutation in a family with congenital aniridia

Congenital aniridia is a rare ocular malformation that presents with severe hypoplasia of the iris and various ocular manifestations. Most cases of congenital aniridia are known to be related to mutations in the paired box gene-6 (PAX6), which is an essential gene in eye development. Herein, we report a familial case of autosomal dominant congenital aniridia with four affected members in 3 consecutive generations and describe the detailed ophthalmologic findings for one of these members. As expected, mutational analysis revealed a nonsense mutation (p.Ser122^*) in the PAX6 gene. Thus, our findings reiterate the importance of PAX6 mutations in congenital aniridia.

Targeted exome sequencing resolves allelic and the genetic heterogeneity in the genetic diagnosis of nephronophthisis-related ciliopathy

Nephronophthisis-related ciliopathy (NPHP-RC) is a common genetic cause of end-stage renal failure during childhood and adolescence and exhibits an autosomal recessive pattern of inheritance. Genetic diagnosis is quite limited owing to genetic heterogeneity in NPHP-RC. We designed a novel approach involving the step-wise screening of Sanger sequencing and targeted exome sequencing for the genetic diagnosis of 55 patients with NPHP-RC. First, five NPHP-RC genes were analyzed by Sanger sequencing in phenotypically classified patients. Known pathogenic mutations were identified in 12 patients (21.8%); homozygous deletions of NPHP1 in 4 juvenile nephronophthisis patients, IQCB1/NPHP5 mutations in 3 Senior–Løken syndrome patients, a CEP290/NPHP6 mutation in 1 Joubert syndrome patient, and TMEM67/MKS3 mutations in 4 Joubert syndrome patients with liver involvement. In the remaining undiagnosed patients, we applied targeted exome sequencing of 34 ciliopathy-related genes to detect known pathogenic mutations in 7 (16.3%) of 43 patients. Another 18 likely damaging heterozygous variants were identified in 13 NPHP-RC genes in 18 patients. In this study, we report a variety of pathogenic and candidate mutations identified in 55 patients with NPHP-RC in Korea using a step-wise application of two genetic tests. These results support the clinical utility of targeted exome sequencing to resolve the issue of allelic and genetic heterogeneity in NPHP-RC.

Bilateral iliac and popliteal arterial thrombosis in a child with focal segmental glomerulosclerosis

Thromboembolic complications (TECs) are clinically important sequelae of nephrotic syndrome (NS). The incidence of TECs in children is approximately 2%–5%. The veins are the most commonly affected sites, particularly the deep veins in the legs, the inferior vena cava, the superior vena cava, and the renal veins. Arterial thrombosis, which is less common, typically occurs in the cerebral, pulmonary, and femoral arteries, and is associated with the use of steroids and diuretics. Popliteal artery thrombosis in children has been described in cases of traumatic dissection, osteochondroma, Mycoplasma pneumoniae infection, and fibromuscular dysplasia. We report of a 33-month-old girl with bilateral iliac and popliteal arterial thrombosis associated with steroid-resistant NS due to focal segmental glomerulosclerosis. Her treatment involved thrombectomy and intravenous heparinization, followed by oral warfarin for 8 months. Herein, we report a rare case of spontaneous iliac and popliteal arterial thrombosis in a young child with NS.

KNOW-Ped CKD (KoreaN cohort study for outcomes in patients with pediatric CKD): Design and methods

Background

The global prevalence of chronic kidney disease (CKD) is increasing. In children, CKD exhibits unique etiologies and can have serious impacts on children’s growth and development. Therefore, an aggressive approach to preventing the progression of CKD and its complications is imperative. To improve the understanding and management of Asian pediatric patients with CKD, we designed and launched KNOW-Ped CKD (KoreaN cohort study for Outcome in patients With Pediatric Chronic Kidney Disease), a nationwide, prospective, and observational cohort study of pediatric CKD with funding from the Korean government.

Methods/design

From seven major centers, 450 patients <20 years of age with CKD stages I to V are recruited for the comprehensive assessment of clinical findings, structured follow-up, and bio-specimen collection. The primary endpoints include CKD progression, defined as a decline of estimated glomerular filtration rate by 50 %, and a requirement for renal replacement therapy or death. The secondary outcomes include the development of left ventricular hypertrophy or hypertension, impairment of growth, neuropsychological status, behavioral status, kidney growth, and quality of life.

Discussion

With this study, we expect to obtain more information on pediatric CKD, which can be translated to better management for the patients.

Trial registration

NCT02165878 (ClinicalTrials.gov), submitted on June 11, 2014.

Risk factors for loss of residual renal function in children treated with chronic peritoneal dialysis

In dialyzed patients, preservation of residual renal function is associated with better survival, lower morbidity, and greater quality of life. To analyze the evolution of residual diuresis over time, we prospectively monitored urine output in 401 pediatric patients in the global IPPN registry who commenced peritoneal dialysis (PD) with significant residual renal function. Associations of patient characteristics and time-variant covariates with daily urine output and the risk of developing oligoanuria (under 100 ml/m²/day) were analyzed by mixed linear modeling and Cox regression analysis including time-varying covariates. With an average loss of daily urine volume of 130 ml/m² per year, median time to oligoanuria was 48 months. Residual diuresis significantly subsided more rapidly in children with glomerulopathies, lower diuresis at start of PD, high ultrafiltration volume, and icodextrin use. Administration of diuretics significantly reduced oligoanuria risk, whereas the prescription of renin–angiotensin system antagonists significantly increased the risk oligoanuria. Urine output on PD was significantly associated in a negative manner with glomerulopathies (−584 ml/m²) and marginally with the use of icodextrin (−179 ml/m²) but positively associated with the use of biocompatible PD fluid (+111 ml/m²). Children in both Asia and North America had consistently lower urine output compared with those in Europe perhaps due to regional variances in therapy. Thus, in children undergoing PD, residual renal function depends strongly on the cause of underlying kidney disease and may be modifiable by diuretic therapy, peritoneal ultrafiltration, and choice of PD fluid.

Familial IPEX syndrome: different glomerulopathy in two siblings

Immune dysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX) syndrome (OMIM 304790) is a rare hereditary disorder of the immune regulatory system caused by FOXP3 mutations. The clinical features of this syndrome include a wide spectrum of severe autoimmune diseases and renal involvement, mostly due to tubulointerstitial diseases, in some patients. Glomerulopathy of membranous nephropathy (MN) and minimal change nephrotic syndrome (MCNS), however, have also been reported. We encountered two children with IPEX syndrome from the same family. Interestingly, they had different glomerular lesions: one had MN and the other had MCNS. Herein we describe the cases of these siblings and review the possible mechanisms for the development of two different renal lesions.

Atypical retinopathy in patients with nephronophthisis type 1: an uncommon ophthalmological finding

BACKGROUND

Progressive retinal degeneration without retinal pigmentation has been repeatedly observed in Korean nephronophthisis (NPHP) type 1 patients with a total homozygous deletion of NPHP1.

DESIGN

Retrospective case series.

PARTICIPANTS

Patients with clinical diagnosis of NPHP and genetic diagnosis of total deletion of NPHP1 (n = 5) were included in this study.

METHODS

Patients with clinical diagnosis of NPHP (n = 57) were screened for total deletion of NPHP1 by polymerase chain reaction (PCR) for the 20 exons of NPHP1. The clinical and ophthalmological findings of NPHP type 1 patients were reviewed. Additionally, four exons of MALL, a gene adjacent to NPHP1, were amplified using PCR, and amplification failure was considered a homozygous deletion encompassing the corresponding exons.

MAIN OUTCOME MEASURE

Ophthalmological findings in NPHP type 1 patients.

RESULTS

Five of 57 patients with clinical diagnosis of NPHP were diagnosed as having NPHP type 1 by genetic analysis. Chronic renal failure was diagnosed in these five patients at 7.9-15.4 years of age. All the patients with NPHP type 1 had progressive decline in visual acuity with various ages of onset (2-17 years). Ophthalmological examinations revealed unexpected findings of retinopathy with large or small flecks, which was compatible with Stargardt-like retinopathy or albipunctatus retinopathy in majority of them (four of five). The genetic study revealed an additional deletion of exon 1 of the adjacent gene MALL.

CONCLUSIONS

We report the unexpectedly common retinal involvement of NPHP type 1 with an additional MALL deletion in a Korean cohort.

Recurrence of idiopathic focal segmental glomerulosclerosis after kidney transplantation: experience of a Korean tertiary center

FSGS is the second most common cause of idiopathic NS in children. It often progresses to ESRD and commonly recurs after KT. To investigate the risk factors and the prognosis of recurrence in pediatric idiopathic FSGS in Korea, retrospective review of 43 KT in 38 children with idiopathic FSGS of last two decades was conducted. The patients presented at the median age of 5.1 yr (range 1.1-13.8 yr) and received KT 5.7 yr later (range 1.3-17.6 yr). FSGS recurred in 20 allografts immediately after transplantation, only in those who presented with NS but not in those who presented with AUA. The risk factors for recurrence were age of onset >5 yr and progression to ESRD within six yr but not sooner than 18 months. CR was achieved in 13 patients with FSGS recurrence and sustained in nine without subsequent relapse over a median of six and a half yr (0.6-20.7 yr). Pediatric idiopathic FSGS presenting with NS recurred in more than half of patients after transplantation. Interestingly, more rapid progression within less than 18 months did not predict recurrence. To identify high-risk patients of recurrence, an international cooperative study would be necessary.

Conversion of twice-daily tacrolimus to once-daily tacrolimus formulation in stable pediatric kidney transplant recipients: pharmacokinetics and efficacy

The pharmacokinetics, efficacy and safety of once-daily tacrolimus formulation (Tac-OD) were assessed in 34 stable pediatric kidney transplant recipients. Enrolled patients received their dose of twice-daily tacrolimus formulation (Tac-BID) on study Days 0 through 7. On the morning of study Day 8, the total daily doses for patients were converted to Tac-OD on a 1:1 basis and maintained on a once-daily morning dosing regimen. Tacrolimus pharmacokinetic profiles were obtained on study Days 7, 14 and 28 (after dose adjustment). Although the mean C0 concentrations (4.10 ± 1.16-3.53 ± 1.10 ng/mL, p = 0.004), and AUC0-24 (151.8 ± 41.6-129.8 ± 39.3 ng h/mL, p < 0.001) were decreased significantly after a 1:1 based conversion, there was high interindividual variability. The dose of Tac-OD was decreased in 26.5% and increased in 44.1% of patients. The resultant tacrolimus dose and pharmacokinetic profiles on study Day 28 were comparable to those on Day 7. There were no serious adverse events. In conclusion, Tac-BID can be safely converted to Tac-OD in stable pediatric kidney transplant patients with the heightened therapeutic drug monitoring. Effects of drug conversion on the cardiovascular risk factors, neurological side effects and adherence should be further evaluated.

Intravenous fluid prescription practices among pediatric residents in Korea

Purpose

Recent studies have established the association between hypotonic fluids administration and hospital-acquired hyponatremia in children. The present paper investigated the pattern of current practice in intravenous fluid prescription among Korean pediatric residents, to underscore the need for updated education.

Methods

A survey-based analysis was carried out. Pediatric residents at six university hospitals in Korea completed a survey consisting of four questions. Each question proposed a unique scenario in which the respondents had to prescribe either a hypotonic or an isotonic fluid for the patient.

Results

Ninety-one responses were collected and analyzed. In three of the four scenarios, a significant majority prescribed the hypotonic fluids (98.9%, 85.7%, and 69.2%, respectively). Notably, 69.2% of the respondents selected the hypotonic fluids for postoperative management. Almost all (96.7%) selected the isotonic fluids for hydration therapy.

Conclusion

In the given scenarios, the majority of Korean pediatric residents would prescribe a hypotonic fluid, except for initial hydration. The current state of pediatric fluid management, notably, heightens the risk of hospital-acquired hyponatremia. Updated clinical practice education on intravenous fluid prescription, therefore, is urgently required.