Baseline characteristics of the Korean genetic cohort of inherited cystic kidney disease

Identifying genetic mutations in individuals with inherited cystic kidney disease is necessary for precise treatment. We aimed to elucidate the genetic characteristics of cystic kidney disease in the Korean population. Methods: We conducted a 3-year prospective, multicenter cohort study at eight hospitals from May 2019 to May 2022. Patients with more than three renal cysts were enrolled and classified into two categories, typical autosomal dominant polycystic kidney disease (ADPKD) and atypical PKD. We identified the clinical characteristics and performed a genetic analysis using a targeted gene panel. Results: A total of 725 adult patients were included in the study, of which 560 (77.2%) were diagnosed with typical ADPKD and 165 (22.8%) had atypical PKD. Among the typical ADPKD cases, the Mayo imaging classification was as follows: 1A (55, 9.9%), 1B (149, 26.6%), 1C (198, 35.8%), 1D (90, 16.3%), and 1E (61, 11.0%). The atypical PKD cases were classified as bilateral cystic with bilateral atrophic (31, 37.3%), lopsided (27, 32.5%), unilateral (nine, 10.8%), segmental (eight, 9.6%), bilateral cystic with unilateral atrophic (seven, 8.4%), and asymmetric (one, 1.2%). Pathogenic variants were found in 64.3% of the patients using the ciliopathy-related targeted gene panel. The typical ADPKD group demonstrated a higher discovery rate (62.3%) than the atypical PKD group (41.8%). Conclusion: We present a nationwide genetic cohort’s baseline clinical and genetic characteristics for Korean cystic kidney disease.

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.

Clinical Outcomes of Non-carbapenem Treatment for Urinary Tract Infections Caused by Extended-spectrum β-lactamase-producing Escherichia coli

Purpose@#The purpose of this study was to investigate the clinical outcomes of non-carbapenem treatment for urinary tract infections (UTIs) caused by extended-spectrum β-lactamase (ESBL)-producing Escherichia coli (E. coli) in young children. @*Methods@#We retrospectively reviewed the medical records of children under 2 years of age who were diagnosed and treated for UTIs caused by ESBL-producing E. coli from September 2014 to March 2020. @*Results@#Forty-three children under 2 years of age were treated with non-carbapenem antimicrobials for UTIs caused by ESBL-producing E. coli without bloodstream infections. The overall clinical and microbiological success rates for empirical antimicrobial treatment were 90.7% and 97.7%. Three of the patients (7.0%) experienced a relapse of UTI within a month. An in vitro susceptibility test showed that two patients were sensitive and one was resistant to the antimicrobial treatments. Furthermore, there were no significant differences in the time to defervescence, clinical success, microbiological success, and relapse rate between the susceptible (n=13) and non-susceptible groups (n=30). @*Conclusion@#In this study, the overall relapse rate of patients treated with non-carbapenem antimicrobials was 7.0%. The patients showed high success rates in the clinical and microbiological responses to the non-carbapenems regardless of the results of the in vitro antimicrobial susceptibility test. These results provide evidence that non-carbapenems may be viable alternative treatments for UTIs caused by ESBL-producing E. coli.

Enuresis as a Presenting Symptom of Graves’ Disease: A Case Report

Enuresis is intermittent urinary incontinence during sleep at night in children aged 5 years or older. The main pathophysiology of enuresis involves nocturnal polyuria, abnormal sleep arousal, and low functional bladder capacity. In rare cases, enuresis is an early symptom of endocrine disorders such as diabetes or thyroid disorders. Herein, we report a case of a 12-year-old girl with enuresis as a rare initial presentation of Graves’ disease. She complained of nocturnal enuresis from a month before visiting our clinic. She also complained of urinary frequency, headache, and weight loss. On physical examination, she had tachycardia, intention tremors, and a diffuse goiter on her anterior neck with bruit on auscultation. Her thyroid function test results revealed hyperthyroidism, and Graves’ disease was diagnosed as the thyroid stimulating hormone receptor autoantibody was positive. After treatment for Graves’ disease with methimazole, symptoms of enuresis resolved within 2 weeks as she became clinically and biochemically euthyroid. In children with secondary enuresis, Graves’ disease should be considered as a differential diagnosis, and signs of hyperthyroidism should be checked for carefully.

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.

Clinical Outcomes of Non-carbapenem Treatment for Urinary Tract Infections Caused by Extended-spectrum β-lactamase-producing Escherichia coli

Purpose@#The purpose of this study was to investigate the clinical outcomes of non-carbapenem treatment for urinary tract infections (UTIs) caused by extended-spectrum β-lactamase (ESBL)-producing Escherichia coli (E. coli) in young children. @*Methods@#We retrospectively reviewed the medical records of children under 2 years of age who were diagnosed and treated for UTIs caused by ESBL-producing E. coli from September 2014 to March 2020. @*Results@#Forty-three children under 2 years of age were treated with non-carbapenem antimicrobials for UTIs caused by ESBL-producing E. coli without bloodstream infections. The overall clinical and microbiological success rates for empirical antimicrobial treatment were 90.7% and 97.7%. Three of the patients (7.0%) experienced a relapse of UTI within a month. An in vitro susceptibility test showed that two patients were sensitive and one was resistant to the antimicrobial treatments. Furthermore, there were no significant differences in the time to defervescence, clinical success, microbiological success, and relapse rate between the susceptible (n=13) and non-susceptible groups (n=30). @*Conclusion@#In this study, the overall relapse rate of patients treated with non-carbapenem antimicrobials was 7.0%. The patients showed high success rates in the clinical and microbiological responses to the non-carbapenems regardless of the results of the in vitro antimicrobial susceptibility test. These results provide evidence that non-carbapenems may be viable alternative treatments for UTIs caused by ESBL-producing E. coli.

Enuresis as a Presenting Symptom of Graves’ Disease: A Case Report

Enuresis is intermittent urinary incontinence during sleep at night in children aged 5 years or older. The main pathophysiology of enuresis involves nocturnal polyuria, abnormal sleep arousal, and low functional bladder capacity. In rare cases, enuresis is an early symptom of endocrine disorders such as diabetes or thyroid disorders. Herein, we report a case of a 12-year-old girl with enuresis as a rare initial presentation of Graves’ disease. She complained of nocturnal enuresis from a month before visiting our clinic. She also complained of urinary frequency, headache, and weight loss. On physical examination, she had tachycardia, intention tremors, and a diffuse goiter on her anterior neck with bruit on auscultation. Her thyroid function test results revealed hyperthyroidism, and Graves’ disease was diagnosed as the thyroid stimulating hormone receptor autoantibody was positive. After treatment for Graves’ disease with methimazole, symptoms of enuresis resolved within 2 weeks as she became clinically and biochemically euthyroid. In children with secondary enuresis, Graves’ disease should be considered as a differential diagnosis, and signs of hyperthyroidism should be checked for carefully.

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

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

The authors regret that there were errors in (Text/Table 1). This notice corrects on page 4 and page 5.

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

The authors regret that there were errors in (Text/Table 1). This notice corrects on page 4 and page 5.

Genetic Basis of Steroid Resistant Nephrotic Syndrome

Steroid-resistant nephrotic syndrome (SRNS) has long been a challenge for clinicians due to its poor responsiveness to immunosuppressants, and rapid progression to end-stage renal disease. Identifying a monogenic cause for SRNS may lead to a better understanding of podocyte structure and function in the glomerular filtration barrier. This review focuses on genes associated with slit diaphragm, actin cytoskeleton, transcription factors, nucleus, glomerular basement membrane, mitochondria, and other proteins that affect podocyte biology.

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

BACKGROUND: Post-transplant lymphoproliferative disease (PTLD) is one of the major complications of organ transplantation, especially in children with Epstein-Barr virus (EBV) viremia (EV). We performed a retrospective study to evaluate risk factors for PTLD in children with EV. METHODS: Among 199 pediatric kidney transplantation (KT) recipients at our center from January 2001 to October 2015, records of those with EBV viral loads of > 1,000 copies/mL and/or PTLD were reviewed. RESULTS: Diagnosis of PTLD was made in seven patients (PTLD group), and 39 patients had EV only (EV only group). The median time from KT to EV and PTLD diagnosis was 6.7 (range 0.4–47.8) months and 8.2 (range, 2.8–98.9) months, respectively. There were no significant differences between the groups in terms of sex, age at transplantation, donor type, EBV viral load, or EV-free duration after KT. Higher tacrolimus level before EV (hazard ratio, 44.5; P = 0.003) was an independent risk factor for PTLD in multivariate Cox regression analysis. Six patients with a high EBV load (median 171,639 copies/mL) were treated with preemptive rituximab (RTX) therapy, resulting in transient reduction of EBV load. None of these patients developed PTLD (median follow-up 51.5 months); however, two had neutropenia and two developed infection requiring hospital admission. CONCLUSION: In pediatric KT recipients, higher tacrolimus levels were associated with a higher incidence of PTLD. Conversely, those who received preemptive RTX for EV did not develop PTLD.

Reninoma: a rare cause of curable hypertension / 소아과

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.

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.

Primary Autosomal Recessive Distal Renal Tubular Acidosis Caused by a Common Homozygous SLC4A1 Mutation in Two Lao Families

Primary distal renal tubular acidosis (dRTA) caused by mutations of the SLC4A1 gene, which encodes for erythroid and kidney isoforms of anion exchanger, shows marked difference in inheritance patterns and clinical features in different parts of the world. While the disease shows autosomal dominant inheritance without any red cell morphological abnormalities in the temperate countries, it is almost invariably recessive, and often accompanies red cell morphological abnormalities or hemolytic anemia in the tropics, especially in Southeast Asia. Here, we report three patients with autosomal recessive (AR) dRTA, presenting with typical findings of failure to thrive and rickets, from two unrelated Lao families. The mutational analyses revealed that all three patients harbored the same homozygous SLC4A1 mutation, p.Gly701Asp. Adequate supplementation of alkali and potassium resulted in remarkable improvement of growth retardation and skeletal deformities of the patients. This is the first case report of Lao patients with AR dRTA caused by SLC4A1 mutations.

Kidney Transplantation in Patients with Atypical Hemolytic Uremic Syndrome due to Complement Factor H Deficiency: Impact of Liver Transplantation

BACKGROUND: Atypical hemolytic uremic syndrome (aHUS) is a rare disease that is often associated with genetic defects. Mutations of complement factor H (CFH) are the most common genetic defects that cause aHUS and often result in end-stage renal disease. Since CFH is mainly produced in the liver, liver transplantation (LT) has been performed in patients with defective CFH. METHODS: The clinical courses of four kidney allograft recipients who lost their native kidney functions due to aHUS associated with a CFH mutation were reviewed. RESULTS: Subject A underwent kidney transplantation (KT) twice, aHUS recurred and the allograft kidney failed within a few years. Subject B received a KT and soon experienced a recurrence of aHUS coinciding with infection. Her allograft kidney function has worsened, and she remains on plasma infusion therapy. Subject C underwent LT followed by KT. She is doing well without plasma infusion therapy after combined LT-KT for 3 years. Subject D received KT following LT and is now recurrence-free from aHUS. CONCLUSION: In patients with aHUS associated with a CFH mutation, KT without LT was complicated with a recurrence of aHUS, which might lead to allograft loss. Conversely, LT was successful in preventing the recurrence of aHUS and thus might be another option for a recurrence-free life for aHUS patients associated with CFH mutation.

A Pediatric Case of Inflammatory Bowel Disease with Renal Amyloidosis

Amyloidosis is a rare disease that results from the deposition of extracellular protein in various body tissues, causing progressive organ dysfunction. Secondary renal amyloidosis is a rare but serious complication of chronic inflammatory bowel disease, particularly in patients with Crohn's disease or ulcerative colitis. We report a case of secondary renal amyloidosis in a pediatric patient who reported a 16-year history of “very early onset inflammatory bowel disease”. Intensive treatment including repeated infliximab infusions improved clinical parameters of inflammatory bowel disease, although renal dysfunction showed progression. Amyloidosis should be considered in patients with IBD, particularly if they suffered disease progression.

A Case of an Ureteropelvic Junction Obstruction Caused by a Crossing Vessel

Ureteropelvic junction obstruction is one of the common causes of hydronephrosis in infancy and childhood. Most cases of ureteropelvic junction obstruction are diagnosed prenatally and are usually asymptomatic. Although less common, older children can experience ureteropelvic junction obstruction that presents with symptoms including flank or abdominal pain. Here, we present the case of a nine-year-old healthy girl who had repeated flank pain and abdominal symptoms, with mild left hydronephrosis, for several months. Computed tomography that was performed during the period of acute flank pain revealed aggravated hydronephrosis on her left kidney, which was secondary to an ureteropelvic junction obstruction. She underwent laparoscopic pyeloplasty, and a crossing vessel that passed the ureteropelvic junction was identified. In addition, we reviewed the current literature of this rare entity.

Disseminated adenovirus infection in a 10-year-old renal allograft recipient

Disseminated adenovirus infection can result in high mortality and morbidity in immunocompromised patients. Here, we report the case of a 10-year-old renal allograft recipient who presented with hematuria and dysuria. Adenovirus was isolated from his urine. His urinary symptoms decreased after intravenous hydration and reduction of immunosuppressants. However, 2 weeks later he presented with general weakness and laboratory tests indicated renal failure necessitating emergency hemodialysis. Adenovirus was detected in his sputum; therefore, intravenous ganciclovir and immunoglobulin therapy were initiated. Renal biopsy revealed diffuse necrotizing granulomatous tubulointerstitial nephritis compatible with renal involvement of the viral infection. Adenovirus was detected in his serum. Despite cidofovir administration for 2 weeks, adenovirus was also detected in the cerebrospinal fluid, resulting in generalized tonic-clonic seizure. The patient died 7 weeks after the onset of urinary symptoms. Adenovirus should be considered in screening tests for post-renal transplantation patients who present with hemorrhagic cystitis.

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.