The spectrum of autosomal dominant polycystic kidney disease in children and adolescents

Diseases of the primary cilia: a clinical characteristics review

Ciliopathies encompass a broad spectrum of diseases stemming from dysfunction of the primary (non-motile) cilia, present on almost all cells in the human body. These disorders include autosomal dominant and recessive polycystic kidney diseases, nephronophthisis, and multisystem ciliopathies such as Joubert, Meckel, Bardet-Biedl, Alström, oral-facial-digital syndromes, and skeletal ciliopathies. The majority of these ciliopathies are associated with fibrocystic kidney disease resulting in progressive kidney dysfunction. In addition, many ciliopathies are associated with extra-renal manifestations including congenital hepatic fibrosis, retinal dystrophy, obesity, and brain and skeletal anomalies. The diagnoses may be challenging due to their overlapping clinical features and molecular heterogeneity. To date, over 190 genes encoding proteins that localize to the primary cilia have been identified as disease-causing. This review will discuss the clinical features of the most frequently encountered disorders of primary cilia.

Overview of clinical status, treatment, and long-term outcomes of pediatric autosomal-dominant polycystic kidney disease: a nationwide survey in Taiwan

This retrospective study investigated the incidence, medication use, and outcomes in pediatric autosomal-dominant polycystic kidney disease (ADPKD) using Taiwan's National Health Insurance Research Database (NHIRD). A 1:4 matched control group of individuals included in the NHIRD during the same period was used for comparative analyses. A total of 621 pediatric patients were identified from 2009 to 2019 (mean age, 9.51 ± 6.43 years), and ADPKD incidence ranged from 2.32 to 4.45 per 100,000 individuals (cumulative incidence, 1.26-1.57%). The incidence of newly developed hypertension, anti-hypertensive agent use, nephrolithiasis, and proteinuria were significantly higher in the ADPKD group than the non-ADPKD group (0.7 vs. 0.04, 2.26 vs. 0.30, 0.4 vs. 0.02, and 0.73 vs. 0.05 per 100 person-years, respectively). The adjusted hazard ratios for developing hypertension, proteinuria, nephrolithiasis and anti-hypertensive agent use in cases of newly-diagnosed pediatric ADPKD were 12.36 (95% CI 4.92-31.0), 13.49 (95% CI 5.23-34.79), 13.17 (95% CI 2.48-69.98), and 6.38 (95% CI 4.12-9.89), respectively. The incidence of congenital cardiac defects, hematuria, urinary tract infections, gastrointestinal diverticulosis, dyslipidemia, and hyperuricemia were also higher in the ADPKD group. Our study offers valuable insights into the epidemiology of pediatric ADPKD in Taiwan and could help in formulating guidelines for its appropriate management.

Severe parental phenotype associates with hypertension in children with ADPKD

BACKGROUND

Early detection of hypertension in children with autosomal polycystic kidney disease (ADPKD) may be beneficial, but screening children at risk of ADPKD remains controversial. We investigated determinants of hypertension in children with ADPKD to help identify a subgroup of children at risk of ADPKD for whom screening for the disease and/or its complications would be more relevant.

METHODS

In a retrospective study including consecutive children with ADPKD aged 5-18 years and followed at Saint-Luc Hospital Brussels between 2006 and 2020, we investigated the potential association between genotype, clinical characteristics and parental phenotype, and presence of hypertension. Hypertension was defined as blood pressure > P95 during 24-h ambulatory monitoring or anti-hypertensive therapy use. Parental phenotype was considered severe based on age at kidney failure, Mayo Clinic Imaging Classification and rate of eGFR decline.

RESULTS

The study enrolled 55 children with ADPKD (mean age 9.9 ± 2.2 years, 45% male), including 44 with a PKD1 mutation and 5 with no mutation identified. Nine (16%) children had hypertension. Hypertension in children was associated with parental phenotype severity (8/27 (30%) children with severe parental phenotype vs. 1/23 (4%) children with non-severe parental phenotype (p = 0.03)) and height-adjusted bilateral nephromegaly (6/9 (67%) children with bilateral nephromegaly vs. 3/44 (7%) children without bilateral nephromegaly (p < 0.001)).

CONCLUSIONS

Severe parental phenotype is associated with higher prevalence of hypertension in children with ADPKD. Hence, children of parents with severe ADPKD phenotype may be those who will most benefit from screening of the disease and/or yearly BP measures. A higher resolution version of the Graphical abstract is available as Supplementary information.

Autosomal Dominant Polycystic Kidney Disease in Children and Adolescents: Assessing and Managing Risk of Progression

The clinical management of autosomal dominant polycystic kidney disease (ADPKD) in adults has shifted from managing complications to delaying disease progression through newly emerging therapies. Regarding pediatric management of the disease, there are still specific hurdles related to the management of children and adolescents with ADPKD and, unlike adults, there are no specific therapies for pediatric ADPKD or stratification models to identify children and young adults at risk of rapid decline in kidney function. Therefore, early identification and management of factors that may modify disease progression, such as hypertension and obesity, are of most importance for young children with ADPKD. Many of these risk factors could promote disease progression in both ADPKD and chronic kidney disease. Hence, nephroprotective measures applied early in life can represent a window of opportunity to prevent the decline of the glomerular filtration rate especially in young patients with ADPKD. In this review, we highlight current challenges in the management of patients with pediatric ADPKD, the importance of early modifying factors in disease progression as well as the gaps and future perspectives in the pediatric ADPKD research field.

Cystic kidney diseases in children

Cystic kidney disease comprises a broad group of heterogeneous diseases, which differ greatly in age at onset, disease manifestation, systemic involvement, disease progression, and long-term prognosis. As our understanding of these diseases continues to evolve and new treatment strategies continue to emerge, correctly differentiating and diagnosing these diseases becomes increasingly important. In this review, we aim to highlight the key features of the most relevant cystic kidney diseases, underscore important diagnostic characteristics of each disease, and present specific management options if applicable.

Novel multi-allelic variants, two BBS2 and one PKD1 variant, of renal ciliopathies: A case report and literature review

BACKGROUND

Bardet-Biedl syndrome (BBS) and autosomal dominant polycystic kidney disease (ADPKD) are renal ciliopathies. BBS has 22 pathogenic genes, and ADPKD is mainly caused by PKD1 and PKD2 variants. Cases with tri-allelic variants of BBS and PKD1 are rare.

CASE PRESENTATION

The proband was an 11-year-old Chinese male with cysts in both kidneys, blurred vision, hyperopia, and short fingers and toes. The patient underwent a kidney transplant due to rapid deterioration of renal failure. During follow-up, a smaller field of vision, a slow increase in height, and a weight gain were observed. In addition, renal function and anemia were improved. High-throughput sequencing analysis showed two heterozygous variants in BBS2 (c.563delT (p.I188Tfs*13) inherited from the father and c.534+1G > t (splicing) from the mother) and one heterozygous variant in PKD1 (c.6223C > T (p.R2075C)) inherited from the mother.

CONCLUSION

This paper reported a ciliopathy patient with multi-allelic variants (two BBS2 variants and one PKD1 variant) that may lead to early symptoms and more rapid progression. An early genetic diagnosis may contribute to predicting disease progression and guiding management and follow-up.

Consensus document on autosomal dominant polycystic kindey disease from the Spanish Working Group on Inherited Kindey Diseases. Review 2020

Autosomal dominant polycystic kidney disease (ADPKD) is the most frequent cause of genetic renal disease and accounts for 6-10% of patients on kidney replacement therapy (KRT). Very few prospective, randomized trials or clinical studies address the diagnosis and management of this relatively frequent disorder. No clinical guidelines are available to date. This is a revised consensus statement from the previous 2014 version, presenting the recommendations of the Spanish Working Group on Inherited Kidney Diseases, which were agreed to following a literature search and discussions. Levels of evidence mostly are C and D according to the Centre for Evidence-Based Medicine (University of Oxford). The recommendations relate to, among other topics, the use of imaging and genetic diagnosis, management of hypertension, pain, cyst infections and bleeding, extra-renal involvement including polycystic liver disease and cranial aneurysms, management of chronic kidney disease (CKD) and KRT and management of children with ADPKD. Recommendations on specific ADPKD therapies are provided as well as the recommendation to assess rapid progression.

Polycystic Kidney Disease–Related Disease Burden in Adolescents With Autosomal Dominant Polycystic Kidney Disease: An International Qualitative Study

Rationale & Objective

Little is known about symptoms and disease impacts in adolescents with autosomal dominant polycystic kidney disease (ADPKD). The objective of the study was to explore these issues from the adolescent patient’s perspective.

Study Design

Observational, qualitative study.

Setting & Participants

Eligible participants were 12-17 years old and had a diagnosis of ADPKD. Semi-structured interviews were conducted in 18 cities in 13 countries to elicit participant experiences of ADPKD-related symptoms and physical, social, and emotional impacts.

Analytical Approach

Interviews were recorded, transcribed, and coded. Symptom and impact frequencies from the interviews were calculated, and representative quotes concerning elicited concepts were collated.

Results

Thirty-three participants (mean age, 14.6 years; 42.4% female) completed interviews. Frequently reported symptoms included urinary urgency (n = 10; 30.3%) and back pain (n = 9; 27.3%). Consistent with previous findings in adults, participants experienced 3 primary types of pain: dull kidney pain, severe or sharp kidney pain, and a feeling of fullness and/or discomfort. Reported disease impacts included avoiding sports and physical activity (n = 10; 30.3%), missing school (n = 6; 18.2%) and social activities (n = 6; 18.2%), and feeling worried (n = 6; 18.2%), sad (n = 4; 12.1%), or frustrated (n = 3; 9.1%) about the disease and their future. Approximately one-fifth of participants (n = 7; 21.2%) reported that they were bothered or impacted by dietary limitations (primarily the need for reduced sodium intake and increased water intake).

Limitations

The study had a small sample size. The researchers were unable to conduct focus groups with participants because of parental preferences.

Conclusions

The findings from this exploratory study indicate that a substantial proportion of adolescents with ADPKD experience physical, social, and emotional impacts from their disease.

Tolvaptan in Pediatric Autosomal Dominant Polycystic Kidney Disease: From Here to Where?

Background

Autosomal dominant polycystic kidney disease (ADPKD) is the most common inherited kidney disorder, accounting for approximately 5% of all ESRD cases worldwide. As a vasopressin receptor 2 antagonist, tolvaptan is the FDA-approved therapeutic agent for ADPKD, which is only made available to a limited number of adult patients; however, its efficacy in pediatric patients has not been reported widely.

Summary

Tolvaptan was shown to delay ADPKD progression in the Tolvaptan Efficacy and Safety in Management of Autosomal Dominant Polycystic Kidney Disease and Its Outcomes (TEMPO) 3:4 study, Replicating Evidence of Preserved Renal Function: an Investigation of Tolvaptan Safety and Efficacy in ADPKD (REPRISE) trial, and other clinical studies. In addition to its effects on aquaretic adverse events and alanine aminotransferase elevation, the effect of tolvaptan on ADPKD is clear, sustained, and cumulative. While ADPKD is a progressive disease, the early intervention has been shown to be important and beneficial in hypotheses as well as in trials. The use of tolvaptan in pediatric ADPKD involves the following challenges: patient assessment, quality of life assessment, cost-effectiveness, safety, and tolerability. The ongoing, phase 3b, 2-part study (ClinicalTrials.gov identifier: NCT02964273) on the evaluation of tolvaptan in pediatric ADPKD (patients aged 12-17 years) may help obtain some insights.

Key Messages

This review focuses on the rationality of tolvaptan use in pediatric patients with ADPKD, the associated challenges, and the suggested therapeutic approaches.

Demographic and clinical characteristics of children with autosomal dominant polycystic kidney disease: a single center experience

Background/aim

In children with autosomal dominant polycystic kidney disease (ADPKD), clinical manifestations range from severe neonatal presentation to renal cysts found by chance. We aimed to evaluate demographic, clinical, laboratory findings, and genetic analysis of children with ADPKD.

Materials and methods

We evaluated children diagnosed with ADPKD between January 2006 and January 2019. The diagnosis was established by family history, ultrasound findings, and/or genetic analysis. The demographic, clinical, and laboratory findings were evaluated retrospectively. Patients <10 years and ≥10 years at the time of diagnosis were divided into 2 groups and parameters were compared between the groups.

Results

There were 41 children (M/F: 18/23) diagnosed with ADPKD. The mean age at diagnosis was 7.2 ± 5.1 (0.6–16.9) years and the follow-up duration was 59.34 ± 40.56 (8–198) months. Five patients (12%) were diagnosed as very early onset ADPKD. All patients had a positive family history. Genetic analysis was performed in 29 patients ( PKD1 mutations in 21, PKD2 mutations in 1, no mutation in 3). Cysts were bilateral in 35 (85%) of the patients. Only one patient had hepatic cysts. No valvular defect was defined in 12 patients detected. Only 1 patient had hypertension. None of them had chronic kidney disease. No difference could be demonstrated in sex, laterality of the cysts, maximum cyst diameter, cyst or kidney enlargement, follow-up duration, or GFR at last visit between Groups 1 and 2.

Conclusion

The majority of children with ADPKD had preserved renal functions and slight cyst enlargement during their follow-up. However, they may have different renal problems deserving closed follow-up.

Metabolic profiling in children and young adults with autosomal dominant polycystic kidney disease

Autosomal dominant polycystic kidney disease (ADPKD) is the most commonly inherited kidney disease. Although children with ADPKD show normal renal function, cyst development is already occurring. In this study, we aimed to identify markers and associated molecular pathways of disease progression in children and young adults with ADPKD. Plasma samples were collected during a 3-year randomized, double-blind, placebo-controlled, phase III clinical trial that was designed to test the efficacy of pravastatin on slowing down ADPKD progression in pediatric patients. Samples from 58 patients were available at baseline and at the 3-year endpoint of the study, respectively. Furthermore, plasma samples from 98 healthy children were used as controls. Metabolomic analysis was performed using liquid chromatography-tandem mass spectrometry and differences in metabolic profiles over time and within study groups were evaluated. While pravastatin therapy led to a decrease in a percent change of total kidney volume (HtTKV) in ADPKD patients, it had minimal effects on metabolite changes. Oxidative stress, endothelial dysfunction, inflammation and immune response were the most affected signaling pathways that distinguished healthy from diseased children. Pathway analysis revealed that metabolites in the arginine metabolism (urea and nitric oxide cycles), asparagine and glutamine metabolism, in the methylation cycle and kynurenine pathway were significantly changed between healthy and children with ADPDK and continued to diverge from the control levels while the disease progressed. Detected metabolite changes were primarily governed by disease progression, and less by pravastatin treatment. Identified metabolic pathways, from arginine and asparagine to kynurenine metabolism could present therapeutic targets and should be further investigated for potential to treat ADPKD progression at an early stage.

Prostatic cyst in a pediatric patient with autosomal dominant polycystic kidney disease

Autosomal dominant polycystic kidney disease (ADPKD) is the most common inheritable form of renal cystic disease and is associated with cysts in other organs. Prostatic cysts are rare though and have not been reported in the paediatric population. Reported is the presence of a prostatic cyst that was incidentally noted on routine sonogram in a 15 year old with ADPKD.

European ADPKD Forum multidisciplinary position statement on autosomal dominant polycystic kidney disease care: European ADPKD Forum and Multispecialist Roundtable participants

Autosomal dominant polycystic kidney disease (ADPKD) is a chronic, progressive condition characterized by the development and growth of cysts in the kidneys and other organs and by additional systemic manifestations. Individuals with ADPKD should have access to lifelong, multidisciplinary, specialist and patient-centred care involving: (i) a holistic and comprehensive assessment of the manifestations, complications, prognosis and impact of the disease (in physical, psychological and social terms) on the patient and their family; (ii) access to treatment to relieve symptoms, manage complications, preserve kidney function, lower the risk of cardiovascular disease and maintain quality of life; and (iii) information and support to help patients and their families act as fully informed and active partners in care, i.e. to maintain self-management approaches, deal with the impact of the condition and participate in decision-making regarding healthcare policies, services and research. Building on discussions at an international roundtable of specialists and patient advocates involved in ADPKD care, this article sets out (i) the principles for a patient-centred, holistic approach to the organization and delivery of ADPKD care in practice, with a focus on multispecialist collaboration and shared-decision making, and (ii) the rationale and knowledge base for a route map for ADPKD care intended to help patients navigate the services available to them and to help stakeholders and decision-makers take practical steps to ensure that all patients with ADPKD can access the comprehensive multispecialist care to which they are entitled. Further multispecialty collaboration is encouraged to design and implement these services, and to work with patient organizations to promote awareness building, education and research.

Is polycystic kidney disease associated with malignancy in children?

Background

Polycystic kidney disease (PKD) is an inherited condition characterized by progressive development of end‐stage renal disease, hypertension, hepatic fibrosis, and cysts in the kidney, liver, pancreas, spleen, thyroid, and epididymis. While malignancies have been reported in association with PKD in adults, the incidence of malignancies in children with PKD is not currently known.

Methods

We report on five patients with a known history of PKD who developed a malignancy as children at the University of California, Los Angeles and the University of Colorado Anschutz Medical Campus. Patients were included from 2012 to 2017.

Results

We present five patients with a history of PKD diagnosed with a malignancy during childhood without any additional known mutations to suggest a genetic predisposition to develop cancer. This includes the first reported case of hepatocellular carcinoma in a patient with autosomal recessive polycystic kidney disease.

Conclusion

Our report illustrates the potential that PKD may be associated with an increased risk for developing cancer, even in children. Further research is necessary to better understand this relationship.

Oxidative stress in autosomal dominant polycystic kidney disease: player and/or early predictor for disease progression?

Autosomal dominant polycystic kidney disease (ADPKD), caused by mutations in PKD1 or PKD2 genes, is the most common hereditary renal disease. Renal manifestations of ADPKD are gradual cyst development and kidney enlargement ultimately leading to end-stage renal disease. ADPKD also causes extrarenal manifestations, including endothelial dysfunction and hypertension. Both of these complications are linked with reduced nitric oxide levels related to excessive oxidative stress (OS). OS, defined as disturbances in the prooxidant/antioxidant balance, is harmful to cells due to the excessive generation of highly reactive oxygen and nitrogen free radicals. Next to endothelial dysfunction and hypertension, there is cumulative evidence that OS occurs in the early stages of ADPKD. In the current review, we aim to summarize the cardiovascular complications and the relevance of OS in ADPKD and, more specifically, in the early stages of the disease. First, we will briefly introduce the link between ADPKD and the early cardiovascular complications including hypertension. Secondly, we will describe the potential role of OS in the early stages of ADPKD and its possible importance beyond the chronic kidney disease (CKD) effect. Finally, we will discuss some pharmacological agents capable of reducing reactive oxygen species and OS, which might represent potential treatment targets for ADPKD.

ADPedKD: A Global Online Platform on the Management of Children With ADPKD

Background

Autosomal dominant polycystic kidney disease (ADPKD) is the most common monogenic cause of renal failure. For several decades, ADPKD was regarded as an adult-onset disease. In the past decade, it has become more widely appreciated that the disease course begins in childhood. However, evidence-based guidelines on how to manage and approach children diagnosed with or at risk of ADPKD are lacking. Also, scoring systems to stratify patients into risk categories have been established only for adults. Overall, there are insufficient data on the clinical course during childhood. We therefore initiated the global ADPedKD project to establish a large international pediatric ADPKD cohort for deep characterization.

Methods

Global ADPedKD is an international multicenter observational study focusing on childhood-diagnosed ADPKD. This collaborative project is based on interoperable Web-based databases, comprising 7 regional and independent but uniformly organized chapters, namely Africa, Asia, Australia, Europe, North America, South America, and the United Kingdom. In the database, a detailed basic data questionnaire, including genetics, is used in combination with data entry from follow-up visits, to provide both retrospective and prospective longitudinal data on clinical, radiologic, and laboratory findings, as well as therapeutic interventions.

Discussion

The global ADPedKD initiative aims to characterize in detail the most extensive international pediatric ADPKD cohort reported to date, providing evidence for the development of unified diagnostic, follow-up, and treatment recommendations regarding modifiable disease factors. Moreover, this registry will serve as a platform for the development of clinical and/or biochemical markers predicting the risk of early and progressive disease.

Early Urinary Biomarkers in Pediatric Autosomal Dominant Polycystic Kidney Disease (ADPKD): No Evidence in the Interest of Urinary Neutrophil Gelatinase-Associated Lipocalin (uNGAL)

Background: Autosomal Dominant Polycystic Kidney Disease (ADPKD) is increasingly diagnosed during childhood by the presence of renal cysts in patients with a positive familial history. No curative treatment is available and early detection and diagnosis confronts pediatricians with the lack of early markers to decide whether to introduce renal-protective agents and prevent the progression of renal failure. Neutrophil Gelatinase-Associated Lipocalin (NGAL) is a tubular protein that has been recently proposed as an early biomarker of renal impairment in the ADPKD adult population. Methods: Urinary NGAL (uNGAL) levels were measured in 15 ADPKD children and compared with 15 age and gender matched controls using parametric, non-parametric, and Bayesian statistics. We also tested the association of uNGAL levels with markers of disease progression, such as proteinuria, albuminuria, blood pressure, and Total Kidney Volume (TKV) using correlation analysis. TKV was calculated by ultrasound, using the ellipsoid method. Results: No difference in mean uNGAL levels was observed between groups (ADPKD: 26.36 ng/ml; Controls: 27.24 ng/ml; P = 0.96). Moreover, no correlation was found between uNGAL and proteinuria (P = 0.51), albuminuria (P = 0.69), TKV (P = 0.68), or mean arterial pressure (P = 0.90). By contrast, TKV was positively correlated with proteinuria (P = 0.04), albuminuria (P = 0.001), and mean arterial pressure (P = 0.03). Conclusion: uNGAL did not confirm its superiority as a marker of disease progression in a pediatric ADPKD population. In the contrary, TKV appears to be an easy measurable variable and may be promising as a surrogate marker to follow ADPKD progression in children.

Unmet needs and challenges for follow-up and treatment of autosomal dominant polycystic kidney disease: the paediatric perspective

Awareness is growing that the clinical course of autosomal dominant polycystic kidney disease (ADPKD) already begins in childhood, with a broad range of both symptomatic and asymptomatic features. Knowing that parenchymal destruction with cyst formation and growth starts early in life, it seems reasonable to assume that early intervention may yield the best chances for preserving renal outcome. Interventions may involve lifestyle modifications, hypertension control and the use of disease-modifying treatments once these become available for the paediatric population with an acceptable risk and side-effect profile. Until then, screening of at-risk children is controversial and not generally recommended since this might cause psychosocial and financial harm. Also, the clinical and research communities are facing important questions as to the nature of potential interventions and their optimal indications and timing. Indeed, challenges include the identification and validation of indicators, both measuring and predicting disease progression from childhood, and the discrimination of slow from rapid progressors in the paediatric population. This discrimination will improve both the cost-effectiveness and benefit-to-risk ratio of therapies. Furthermore, we will need to define outcome measures, and to evaluate the possibility of a potential therapeutic window of opportunity in childhood. The recently established international register ADPedKD will help in elucidating these questions. In this review, we provide an overview of the current knowledge on paediatric ADPKD as a future therapeutic target population and its unmet challenges.

Retrospective analysis of simple and stage II renal cysts: Pediatric nephrology point of view

BACKGROUND

Increased ultrasonography (US) use has been correlated with an increased incidence of pediatric renal cysts. For simple and stage II cysts, the malignancy risk is low in adulthood, no follow up is recommended; but there is no consensus on childhood management. Given that pediatric renal cysts may be manifestations of hereditary cystic diseases, a different approach and follow up should be taken for these patients. Herein we present the clinical characteristics and follow-up data of pediatric patients with simple and stage II renal cysts.

METHODS

This cross-sectional study involved 57 children (mean age, 12.44 ± 3.65 years) with simple (n = 35) and stage II cysts (n = 22) who were diagnosed and followed at the present institution for ≥2 years.

RESULTS

The median follow-up period was 2.84 years for simple and 3.10 years for stage II cysts. None of the patients developed complications. No change in cyst diameter was detected in 65.7% of simple or in 45.5% of stage II cysts, whereas 13 simple cysts (37.1%) and eight stage II cysts (36.4%) increased in diameter. The diameter change per year was significantly higher in the stage II cysts than in the simple cysts (P = 0.017). Overall, 13 patients (22%) had an estimated glomerular filtration rate <90 mL/min/1.73 m² , and two patients had hypertension.

CONCLUSION

Although the malignancy risk of simple and stage II kidney cysts is low for this age group, potential complications such as renal dysfunction, hypertension and hereditary cystic disease should be closely monitored.

Urologic Diseases Germane to the Medical Renal Biopsy: Review of a Large Diagnostic Experience in the Context of the Renal Architecture and Its Environs

The kidney is one of the most complicated organs in development and is susceptible to more types of diseases than other organs. The disease spectrum includes developmental and cystic diseases, involvement by systemic diseases, iatrogenic complications, ascending infections and urinary tract obstruction, and neoplastic diseases. The diagnosis of kidney disease is unique involving 2 subspecialties, urologic pathology and renal pathology. Both renal and urologic pathologists employ the renal biopsy as a diagnostic modality. However, urologic pathologists commonly have a generous specimen in the form of a nephrectomy or partial nephrectomy while a renal pathologist requires ancillary modalities of immunofluorescence and electron microscopy. The 2 subspecialties differ in the disease spectrum they diagnose. This separation is not absolute as diseases of one subspecialty not infrequently appear in the diagnostic materials of the other. The presence of medical renal diseases in a nephrectomy specimen is well described and recommendations for reporting these findings have been formalized. However, urologic diseases appearing in a medical renal biopsy have received less attention. This review attempts to fill that gap by first reviewing the perirenal anatomy to illustrate why inadvertent biopsy of adjacent organs occurs and determine its incidence in renal biopsies followed by a discussion of gross anatomic features relevant to the microscopic domain of the medical renal biopsy. Unsuspected neoplasms and renal cysts and cystic kidney diseases will then be discussed as they create a diagnostic challenge for the renal pathologist who often has limited training and experience in these diseases.

Early cardiovascular manifestations in children and adolescents with autosomal dominant polycystic kidney disease: a single center study

BACKGROUND

This study aims to describe the cardiovascular manifestations in children with autosomal dominant polycystic kidney disease (ADPKD) and detect their relation with kidney disease and type of gene mutation.

METHODS

Twenty-one patients (7 to 19 years old) were included. Cardiovascular evaluation involved blood pressure (BP), indexed left ventricular mass (LVMI), pulse wave velocity (PWV), and carotid intima media thickness (cIMT) measurement. Patients were classified according to percentile reference values of these parameters in healthy children. The 95th percentile was the highest level of normal values. Glomerular filtration rate (GFR) and microalbuminuria were also measured.

RESULTS

Antihypertensive treatment, large LVMI, high PWV, and increased cIMT were observed in 6 (28.6%), 2 (9.5%), 4 (19%), and 8 (38.1%) patients respectively. Antihypertensive treatment was not associated with either high PWV or increased cIMT. Linear correlation was noticed between LVMI and PWV (r² = 0.243, p = 0.023) and also between LVMI and cIMT (r² = 0.203, p = 0.041). The median age of patients with high PWV, increased cIMT, and large LVMI was 9.5, 13, and 18 years old. GFR was normal in all patients. Patients with increased cIMT presented higher levels of urine microalbumin to creatinine ratio (p = 0.025). Genetic mutation was available in 18 patients. Antihypertensive treatment was more frequent in patients without PKD1 missense mutation (p = 0.044).

CONCLUSIONS

High PWV and increased cIMT indicating arterial stiffness and hypertrophic vasculopathy may be present in children with ADPKD regardless BP status, and prior to GFR decline, suggesting that vascular disease precedes chronic kidney disease in ADPKD.

Prevalence of Hypertension in Children with Early-Stage ADPKD

BACKGROUND AND OBJECTIVES

Autosomal dominant polycystic kidney disease is the most common inheritable kidney disease, frequently thought to become symptomatic in adulthood. However, patients with autosomal dominant polycystic kidney disease may develop signs or symptoms during childhood, in particular hypertension. Although ambulatory BP monitoring is the preferred method to diagnose hypertension in pediatrics, data in children with autosomal dominant polycystic kidney disease are limited.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Our retrospective multicenter study was conducted to collect ambulatory BP monitoring recordings from patients with autosomal dominant polycystic kidney disease age <18 years old. Basic anthropometric parameters as well as data on kidney function, BP treatment, and kidney ultrasound were also collected.

RESULTS

Data from 310 children with autosomal dominant polycystic kidney disease with a mean age of 11.5±4.1 years old were collected at 22 European centers. At the time when ambulatory BP monitoring was performed, 95% of children had normal kidney function. Reference data for ambulatory BP monitoring were available for 292 patients. The prevalence rates of children with hypertension and/or those who were treated with antihypertensive drugs were 31%, 42%, and 35% during daytime, nighttime, or the entire 24-hour cycle, respectively. In addition, 52% of participants lacked a physiologic nocturnal BP dipping, and 18% had isolated nocturnal hypertension. Logistic regression analysis showed a significant association between a categorical cyst score that was calculated on the basis of the number of cysts >1 cm per kidney and daytime hypertension (odds ratio, 1.70; 95% confidence interval, 1.21 to 2.4; P=0.002), nighttime hypertension (odds ratio, 1.31; 95% confidence interval, 1.05 to 1.63; P=0.02), or 24-hour hypertension (odds ratio, 1.39; 95% confidence interval, 1.08 to 1.81; P=0.01). Kidney length, expressed as SD score, was also significantly associated with nighttime hypertension (odds ratio, 1.23; 95% confidence interval, 1.06 to 1.42; P=0.10).

CONCLUSIONS

These data indicate high prevalence of hypertension in children with autosomal dominant polycystic kidney disease starting at young ages.

3DUS as an alternative to MRI for measuring renal volume in children with autosomal dominant polycystic kidney disease

BACKGROUND

Total kidney volume, measured by magnetic resonance imaging (MRI), is a validated disease progression marker in adults with autosomal dominant polycystic kidney disease (ADPKD). However, in childhood, MRI is burdensome, explaining the need for alternatives.

METHODS

Kidney volume (KV) was evaluated in 30 children with ADPKD, using three-dimensional ultrasound (3DUS), applying the ellipsoid method and manual contouring (KV_{3DUS-ellipsoid,} KV_3DUS-contour respectively); manual contouring on MRI (KV_MRI), and the ellipsoid method on two-dimensional ultrasound (2DUS, KV_2DUS). Correlations and differences were evaluated using Pearson's r and Wilcoxon signed-rank tests, and variability using Bland-Altman plots.

RESULTS

All ultrasound volumetry methods showed significantly lower mean (± SD) KV (mL), compared with MRI-KV_2DUS: 159 (±101); K_{3DUS-ellipsoid}: 169 (±105); KV_3DUS-contour: 185 (±110); KV_MRI: 206 (±130); all p < 0.001. All had a strong correlation with KV_MRI: 2DUS: r = 0.96; 3DUS-ellipsoid: r = 0.89 and 3DUS-contour: r = 0.94. Both before and after correction factor application, Bland-Altman plots showed lower variability and absolute error for KV_3DUS-contour vs KV_2DUS and KV_{3DUS-ellipsoid}.

CONCLUSIONS

Compared with MRI, ultrasound volumetry was prone to underestimation. However, KV_3DUS-contour represents a valuable alternative for MRI in early ADPKD. Although more time-consuming, KV_3DUS-contour is recommended over KV_2DUS for estimation and follow-up of KV in ADPKD children, given its smaller error.

Evidence for Bone and Mineral Metabolism Alterations in Children With Autosomal Dominant Polycystic Kidney Disease

CONTEXT

Autosomal dominant polycystic kidney disease (ADPKD) is the most common hereditary kidney disease. Hypophosphatemia was demonstrated in adult patients with preserved renal function, together with high fibroblast growth factor 23 (FGF23) and low soluble Klotho levels. The latter explained the relative FGF23 hyporesponsiveness in this cohort.

OBJECTIVE

Evaluating phosphate and bone mineral metabolism in children with ADPKD compared with what is known in adult ADPKD patients.

DESIGN

Observational cross-sectional study.

SETTING

Multicenter study via ambulatory care in tertiary centers.

PARTICIPANTS

Ninety-two children with ADPKD (52 males; mean ± standard deviation age, 10.2 ± 5.0 years) and 22 healthy controls (HCs, 10 males; mean ± standard deviation age, 10.3 ± 4.1 years).

MAIN OUTCOME MEASURES

The predictor was early ADPKD stage. Bone mineral metabolism and renal phosphate handling were the main outcome measures. Performed measurements were serum phosphate, tubular maximum phosphorus reabsorption per glomerular filtration rate, FGF23, soluble Klotho, sclerostin, and bone alkaline phosphatase.

RESULTS

ADPKD children had significantly lower serum phosphate levels compared with HC. Low tubular maximum phosphorus reabsorption per glomerular filtration rate was observed in 24% of patients, although not significantly different from HC. Serum FGF23 and soluble Klotho levels were comparable between patients and HC. In addition, we showed decreased bone alkaline phosphatase levels in ADPKD children, suggesting suppressed bone formation.

CONCLUSIONS

This report demonstrates hypophosphatemia and suppressed bone formation in a pediatric ADPKD cohort, with preserved renal function, compared with HC. Although FGF23 levels were not different from controls, they should be considered inappropriate, given the concomitant hypophosphatemia. Further studies are required to elucidate underlying pathophysiology and potential clinical consequences.

Clinicians' attitude towards family planning and timing of diagnosis in autosomal dominant polycystic kidney disease

Several ethical aspects in the management of Autosomal Dominant Polycystic Kidney Disease (ADPKD) are still controversial, including family planning and testing for disease presence in at-risk individuals. We performed an online survey aiming to assess the opinion and current clinical practice of European pediatric and adult nephrologists, as well as geneticists. A total of 410 clinicians (53% male, mean (SD) age of 48 (10) years) responded, including 216 pediatric nephrologists, 151 adult nephrologists, and 43 clinical geneticists. While the 3 groups agreed to encourage clinical testing in asymptomatic ADPKD minors and adults, only geneticists would recommend genetic testing in asymptomatic at-risk adults (P<0.001). Statistically significant disagreement between disciplines was observed regarding the ethical justification of prenatal genetic diagnosis, termination of pregnancy and pre-implantation genetic diagnosis (PGD) for ADPKD. Particularly, PGD is ethically justified according to geneticists (4.48 (1.63)), whereas pediatric (3.08 (1.78); P<0.001) and adult nephrologists (3.66 (1.88); P<0.05) appeared to be less convinced. Our survey suggests that most clinicians support clinical testing of at-risk minors and adults in ADPKD families. However, there is no agreement for genetic testing in asymptomatic offspring and for family planning, including PGD. The present data highlight the need for a consensus among clinicians, to avoid that ADPKD families are being given conflicting information.

Is Autosomal Dominant Polycystic Kidney Disease Becoming a Pediatric Disorder?

Autosomal dominant polycystic kidney disease (ADPKD) affects 1 in 400 to 1,000 live births, making it the most common monogenic cause of renal failure. Although no definite cure is available yet, it is important to affect disease progression by influencing modifiable factors such as hypertension and proteinuria. Besides this symptomatic management, the only drug currently recommended in Europe for selected adult patients with rapid disease progression, is the vasopressin receptor antagonist tolvaptan. However, the question remains whether these preventive interventions should be initiated before extensive renal damage has occurred. As renal cyst formation and expansion begins early in life, frequently in utero, ADPKD should no longer be considered an adult-onset disease. Moreover, the presence of hypertension and proteinuria in affected children has been reported to correlate well with disease severity. Until now, it is controversial whether children at-risk for ADPKD should be tested for the presence of the disease, and if so, how this should be done. Herein, we review the spectrum of pediatric ADPKD and discuss the pro and contra of testing at-risk children and the challenges and unmet needs in pediatric ADPKD care.