Prognosis of autosomal dominant polycystic kidney disease diagnosed in utero or at birth

Ultrasound and magnetic resonance imaging features of fetal urogenital anomalies: A pictorial essay

This pictorial essay focuses on ultrasound (US) and magnetic resonance imaging (MRI) features of fetal urogenital anomalies. Fetal urogenital malformations account for 30%-50% of all anomalies discovered during pregnancy or at birth. They are usually detected by fetal ultrasound exams. However, when ultrasound data on their characteristics is insufficient, MRI is the best option for detecting other associated anomalies. The prognosis highly depends on their type and whether they are associated with other fetal abnormalities.

Case Report: Autosomal dominant polycystic kidney disease and Wilms' tumor in infancy and childhood

Background

Autosomal dominant polycystic kidney disease (ADPKD) is rare but one of the most common inherited kidney diseases. Normal kidney function is maintained until adulthood in most patients. About 7 in 10 patients with ADPKD develop kidney failure in the latter half of their fifth decade of life. Wilms' tumor, or nephroblastoma, is the most common malignant tumor stemming from kidney cells in the pediatric age group. This type of tumor is the most frequently occurring kidney malignancy in children between the ages of 0 and 5 years. The exact cause of Wilms' tumor is unknown, though about 10% of cases have a genetic predisposition. Wilms' tumor is one of the most successfully treated childhood oncological diseases. Overall, the 5-year survival rates were approximately 90% in both the National Wilms Tumor Study (NWTS) and Paediatric Oncology SIOP studies, showing similar results.

Case presentation

We report a case of a girl diagnosed with autosomal polycystic kidney disease, who subsequently developed Wilms' tumor and underwent successful treatment with chemotherapy. Polycystic kidney disease was suspected in the fetus during prenatal ultrasound and confirmed after birth with ultrasound and genetic testing. The Wilms tumor was an accidental finding during abdominal MRI at the age of 2 years old to rule out liver pathology.

Conclusion

Reports on whether a diagnosis of ADPKD is a risk factor for malignancy are conflicting. In this particular case, Wilms' tumor is present in the background of polycystic kidney disease and was timely diagnosed by an incidental MRI.

Mutation Analysis of PKD1 and PKD2 Genes in a Large Italian Cohort Reveals Novel Pathogenic Variants Including a Novel Complex Rearrangement

BACKGROUND

Autosomal dominant polycystic kidney disease (ADPKD) is the most common inherited disease of the kidney. It occurs in adulthood but is also rarely diagnosed in early childhood. The majority of the disease-causing variants observed in ADPKD patients are in two genes: PKD1 and PKD2.

METHODS

237 patients from 198 families with a clinical diagnosis of ADPKD were screened for PKD1 and PKD2 genetic variants using Sanger sequencing and multiple ligation-dependent probe amplification analysis.

RESULTS

Disease-causing (diagnostic) variants were identified in 173 families (211 patients), 156 on PKD1 and 17 on PKD2. Variants of unknown significance were detected in 6 additional families, while no mutations were found in the remaining 19 families. Among the diagnostic variants detected, 51 were novel. In ten families, seven large rearrangements were found and the molecular breakpoints of 3 rearrangements were identified. Renal survival was significantly worse for PKD1-mutated patients, particularly those carrying truncating mutations. In patients with PKD1 truncating (PKD1-T) mutations, disease onset was significantly earlier than in patients with PKD1 non-truncating variants or PKD2-mutated patients.

CONCLUSIONS

Comprehensive genetic testing confirms its utility in diagnosing patients with ADPKD and contributes to explaining the clinical heterogeneity observed in this disease. Moreover, the genotype-phenotype correlation can allow for a more accurate disease prognosis.

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.

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.

The wind of change in the management of autosomal dominant polycystic kidney disease in childhood

Significant progress has been made in understanding the genetic basis of autosomal dominant polycystic kidney disease (ADPKD), quantifying disease manifestations in children, exploring very-early onset ADPKD as well as pharmacological delay of disease progression in adults. At least 20% of children with ADPKD have relevant, yet mainly asymptomatic disease manifestations such as hypertension or proteinuria (in line with findings in adults with ADPKD, where hypertension and cardiovascular damage precede decline in kidney function). We propose an algorithm for work-up and management based on current recommendations that integrates the need to screen regularly for hypertension and proteinuria in offspring of affected parents with different options regarding diagnostic testing, which need to be discussed with the family with regard to ethical and practical aspects. Indications and scope of genetic testing are discussed. Pharmacological management includes renin-angiotensin system blockade as first-line therapy for hypertension and proteinuria. The vasopressin receptor antagonist tolvaptan is licensed for delaying disease progression in adults with ADPKD who are likely to experience kidney failure. A clinical trial in children is currently ongoing; however, valid prediction models to identify children likely to suffer kidney failure are lacking. Non-pharmacological interventions in this population also deserve further study.

The term CAKUT has outlived its usefulness: the case for the prosecution

CAKUT stands for Congenital Anomalies of the Kidney and Urinary Tract, and the acronym first appeared in a review article published in 1998. Since then, CAKUT has become a familiar term encountered in the medical literature, especially in nephrology journals. I reason that the term CAKUT was conceived as not a simple description of various diseases, but more as shorthand for a bold conceptual package that linked the occurrence of diverse types of anatomical malformations with insights from genetic and developmental biology research. Moreover, the angiotensin II receptor type 2 was seen as a paradigmatic molecule in the pathobiology of CAKUT. I contend that the acronym, while appearing as an intellectually good idea at the time it was conceived, has outlived its usefulness. To reach these conclusions, I focus on the complex of research observations that led to the theory behind CAKUT, and then question whether these scientific foundations still stand firm. In addition, it is noted that not all clinicians have adopted the acronym, and I speculate why this is the case. I proceed to demonstrate that there is an incompatibility between the semantic meaning of CAKUT and the diseases for which the term was originally conceived. Instead, I suggest the acronym UTM, standing for Urinary Tract Malformation, is a simpler and less ambiguous one to use. Finally, I contend that the continued use of the acronym is a regressive step for the disciplines of nephrology and urology, taking us back two centuries when all kidney diseases were simply called Bright's disease.

Generation of heterozygous PKD1 mutant pigs exhibiting early-onset renal cyst formation

Autosomal dominant polycystic kidney disease (ADPKD) is the most common inherited kidney disease, manifesting as the progressive development of fluid-filled renal cysts. In approximately half of all patients with ADPKD, end-stage renal disease results in decreased renal function. In this study, we used CRISPR-Cas9 and somatic cell cloning to produce pigs with the unique mutation c.152_153insG (PKD1^insG/+). Pathological analysis of founder cloned animals and progeny revealed that PKD1^insG/+ pigs developed many pathological conditions similar to those of patients with heterozygous mutations in PKD1. Pathological similarities included the formation of macroscopic renal cysts at the neonatal stage, number and cystogenic dynamics of the renal cysts formed, interstitial fibrosis of the renal tissue, and presence of a premature asymptomatic stage. Our findings demonstrate that PKD1^insG/+ pigs recapitulate the characteristic symptoms of ADPKD.

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.

PKD1-Dependent Renal Cystogenesis in Human Induced Pluripotent Stem Cell-Derived Ureteric Bud/Collecting Duct Organoids

BACKGROUND

Autosomal dominant polycystic kidney disease (ADPKD) is the most common hereditary kidney disease leading to renal failure, wherein multiple cysts form in renal tubules and collecting ducts derived from distinct precursors: the nephron progenitor and ureteric bud (UB), respectively. Recent progress in induced pluripotent stem cell (iPSC) biology has enabled cyst formation in nephron progenitor-derived human kidney organoids in which PKD1 or PKD2, the major causative genes for ADPKD, are deleted. However, cysts have not been generated in UB organoids, despite the prevalence of collecting duct cysts in patients with ADPKD.

METHODS

CRISPR-Cas9 technology deleted PKD1 in human iPSCs and the cells induced to differentiate along pathways leading to formation of either nephron progenitor or UB organoids. Cyst formation was investigated in both types of kidney organoid derived from PKD1-deleted iPSCs and in UB organoids generated from iPSCs from a patient with ADPKD who had a missense mutation.

RESULTS

Cysts formed in UB organoids with homozygous PKD1 mutations upon cAMP stimulation and, to a lesser extent, in heterozygous mutant organoids. Furthermore, UB organoids generated from iPSCs from a patient with ADPKD who had a heterozygous missense mutation developed cysts upon cAMP stimulation.

CONCLUSIONS

Cysts form in PKD1 mutant UB organoids as well as in iPSCs derived from a patient with ADPKD. The organoids provide a robust model of the genesis of ADPKD.

Monkeys mutant for PKD1 recapitulate human autosomal dominant polycystic kidney disease

Autosomal dominant polycystic kidney disease (ADPKD) caused by PKD1 mutations is one of the most common hereditary disorders. However, the key pathological processes underlying cyst development and exacerbation in pre-symptomatic stages remain unknown, because rodent models do not recapitulate critical disease phenotypes, including disease onset in heterozygotes. Here, using CRISPR/Cas9, we generate ADPKD models with PKD1 mutations in cynomolgus monkeys. As in humans and mice, near-complete PKD1 depletion induces severe cyst formation mainly in collecting ducts. Importantly, unlike in mice, PKD1 heterozygote monkeys exhibit cyst formation perinatally in distal tubules, possibly reflecting the initial pathology in humans. Many monkeys in these models survive after cyst formation, and cysts progress with age. Furthermore, we succeed in generating selective heterozygous mutations using allele-specific targeting. We propose that our models elucidate the onset and progression of ADPKD, which will serve as a critical basis for establishing new therapeutic strategies, including drug treatments.

International consensus statement on the diagnosis and management of autosomal dominant polycystic kidney disease in children and young people

These recommendations were systematically developed on behalf of the Network for Early Onset Cystic Kidney Disease (NEOCYST) by an international group of experts in autosomal dominant polycystic kidney disease (ADPKD) from paediatric and adult nephrology, human genetics, paediatric radiology and ethics specialties together with patient representatives. They have been endorsed by the International Pediatric Nephrology Association (IPNA) and the European Society of Paediatric Nephrology (ESPN). For asymptomatic minors at risk of ADPKD, ongoing surveillance (repeated screening for treatable disease manifestations without diagnostic testing) or immediate diagnostic screening are equally valid clinical approaches. Ultrasonography is the current radiological method of choice for screening. Sonographic detection of one or more cysts in an at-risk child is highly suggestive of ADPKD, but a negative scan cannot rule out ADPKD in childhood. Genetic testing is recommended for infants with very-early-onset symptomatic disease and for children with a negative family history and progressive disease. Children with a positive family history and either confirmed or unknown disease status should be monitored for hypertension (preferably by ambulatory blood pressure monitoring) and albuminuria. Currently, vasopressin antagonists should not be offered routinely but off-label use can be considered in selected children. No consensus was reached on the use of statins, but mTOR inhibitors and somatostatin analogues are not recommended. Children with ADPKD should be strongly encouraged to achieve the low dietary salt intake that is recommended for all children.

Prenatal ultrasonography of autosomal dominant polycystic kidney disease mimicking recessive type: case series

BACKGROUND

Autosomal dominant polycystic kidney disease (ADPKD) is the most common inherited renal disease. This pathology has been increasingly diagnosed in utero and several sonographic patterns are well described in the literature.

OBJECTIVE

To present a series of fetuses with an unusual imaging pattern of ADPKD, mimicking autosomal recessive polycystic kidney disease (ARPKD).

MATERIALS AND METHODS

We retrospectively reviewed second-line ultrasound (US) scans performed for suspicion of fetal kidney pathology between 2006 and 2018. Inclusion criteria were (1) proven ADPKD on the basis of a known family history and/or of genetic testing and (2) US features suggestive of ARPKD. We recorded the clinical, imaging, genetic and pathological findings in cases with pregnancy termination.

RESULTS

Three out of 12 patients with proven ADPKD diagnosed in utero presented with US features suggestive of ARPKD. Furthermore, an additional patient observed at another institution was added to the series. History of familial ADPKD was present in three cases. US showed enlarged kidneys with increased cortical echogenicity, decreased corticomedullary differentiation, multiple medullary cysts and decreased amniotic fluid in all four cases. Pregnancy was terminated in two cases (histology confirmed features in keeping with ADPKD), one premature neonate died (histology in progress) and one child is alive. Genetic testing showed a homozygous mutation of the PKD1 gene in two patients, a heterozygous mutation of the PKD1 gene in one patient and was not performed in the remaining patient.

CONCLUSION

This series describes an unusual sonographic prenatal presentation of ADPKD, not yet well described in the radiologic literature, mimicking ARPKD.

Clinical practice guideline monitoring children and young people with, or at risk of developing autosomal dominant polycystic kidney disease (ADPKD)

Autosomal Dominant Polycystic Kidney Disease (ADPKD) is thought to affect about 1 in 1000 people in the UK. ADPKD causes a progressive decline in kidney function, with kidney failure tending to occur in middle age. Children and young people with ADPKD may not have any symptoms. However they may have high blood pressure, which may accelerate progression to later stages of chronic kidney disease.There is uncertainty and variation in how health professionals manage children and young people with confirmed or a family history of ADPKD, because of a lack of evidence. For example, health professionals may be unsure about when to test children's blood pressure and how often to monitor it in the hospital clinic or at the GP. They may have different approaches in recommending scanning or genetic testing for ADPKD in childhood, with some recommending waiting until the young person is mature enough to make this decision his or herself.This guideline is intended to help families affected by ADPKD by making sure that: health professionals with specialist knowledge in ADPKD offer you information on inheritance and potential benefits and harms of testing for ADPKD. the decision to test and the method of testing for ADPKD in children and young people is shared between you or your family and the health professionals blood pressure assessment is undertaken regularly in children and young people at risk of developing ADPKD.

Affected parent sex and severity of autosomal dominant polycystic kidney disease: a retrospective cohort study

Objective: Parental inheritance may differentially affect autosomal dominant polycystic kidney disease (ADPKD) severity via genetic imprinting or in utero epigenetic modifications; however, evidence is inconsistent. We conducted a longitudinal retrospective cohort study to assess the association between sex of the affected parent and time to hypertension diagnosis, end-stage renal disease (ESRD), and death in patients with the PKD1 genotype. Materials and methods: 814 individuals who participated in research at the University of Colorado were studied. Kaplan-Meier survival analysis was performed. The predictor was parental sex, and outcomes were diagnosis of hypertension, progression to ESRD, and death. We also examined associations in four strata according to affected parent and participant sex, as previous studies have reported earlier onset of ESRD in males compared to females. Results: The median follow-up for each outcome was as follows: hypertension, 30 (interquartile range (IQR): 18, 37); ESRD, 43 (IQR: 31, 52), death 39 (IQR: 25, 52) years of age. Among affected offspring in the entire cohort, there was no difference in hypertension diagnosis (p = 0.97) or progression to ESRD (p = 0.79) according to affected parent sex; however, participants with an affected mother were more likely to die than participants with an affected father (p < 0.05). In stratified analyses, males were more likely than females to develop hypertension and reach ESRD when the affected parent was the father (p < 0.01) but not when the affected parent was the mother (p ≥ 0.11). Conclusions: Our results are largely in contrast to the hypothesis that severity of ADPKD is worse with maternal inheritance of disease.

Renal cystic disease and associated ciliopathies

PURPOSE OF REVIEW

To review disorders that are associated with renal cystic disease during prenatal life and to highlight the strong association between renal cystic disease and ciliopathies.

RECENT FINDINGS

There are numerous causative genes for ciliopathies that can present with cystic kidney disease. In the group of single gene ciliopathies, autosomal dominant polycystic kidney disease is by far the most prevalent one. Other examples are autosomal recessive polycystic kidney disease, nephronophthisis, Bardet-Biedl syndrome, Meckel-Gruber syndrome, Joubert syndrome and related disorders as well as X-linked orofaciodigital syndrome type 1, respectively. The prevalence of these inherited disorders sums up to about in 1 : 2000 people. These disorders with their hepatorenal fibrocystic character should be classified as multisystem diseases.

SUMMARY

Understanding of the origin of renal cystic disease and associated disorders is important to make the appropriate prenatal diagnosis and for counseling affected parents. In the future, understanding of the pathophysiology may help to develop new treatment strategies.

Prenatal ultrasound, genotype, and outcome in a large cohort of prenatally affected patients with autosomal-recessive polycystic kidney disease and other hereditary cystic kidney diseases

PURPOSE

To investigate the sonographic and clinical genotype-phenotype correlations in autosomal recessive polycystic kidney disease (ARPKD) and other cystic kidney diseases (CKD) in a large cohort of prenatally detected fetuses with hereditary CKD.

METHODS

We retrospectively studied the clinical and diagnostic data of 398 patients referred with prenatal ultrasound findings suggestive of CKD between 1994 and 2010. Cases with confirmed hereditary CKD (n = 130) were analyzed as to their prenatal ultrasound findings, genotype, and possible predictors of clinical outcome.

RESULTS

ARPKD was most common in our non-representative sample. Truncating PKHD1 mutations led to a significantly reduced neonatal prognosis, with two such mutations being invariably lethal. Sonographically visible kidney cysts occurred in only 3% of ARPKD cases. Renal abnormalities in Meckel syndrome (MKS) appeared earlier than in ADPKD (19.6 ± 3.7 vs. 29.8 ± 5.1 GW) or ARPKD (19.6 ± 3.7 vs. 30.2 ± 1.2 GW). Additional CNS malformations were not found in ARPKD, but were highly sensitive for MKS. Pulmonary hypoplasia, oligo/anhydramnios (OAH), and kidney enlargement were associated with a significantly worse neonatal prognosis.

CONCLUSION

Genotype, sonographic signs of OAH, enlarged kidney size, and pulmonary hypoplasia can be useful predictors of neonatal survival. We propose sonographic morphological criteria for ARPKD, ADPKD, MKS, and renal cyst and diabetes syndrome (RCAD). We further propose a clinical diagnostic algorithm for differentiating cystic kidney diseases.

Hypertension in autosomal dominant polycystic kidney disease: a meta-analysis

CONTEXT

Autosomal dominant polycystic kidney disease (ADPKD) is a common disorder that can cause hypertension during childhood, but the true prevalence of hypertension during childhood is not known.

OBJECTIVE

We undertook a systematic review and meta-analysis to determine the prevalence of hypertension in children with ADPKD.

DATA SOURCES

Systematic review of articles published between 1980 and 2015 in MEDLINE and EMBASE.

STUDY SELECTION

Studies selected by two authors independently if reporting data on prevalence of hypertension in children and young persons aged <21 years with a diagnosis of ADPKD. Observational series were included with study populations of >15 children. Articles were excluded if inadequate diagnostic criteria for hypertension were used. Studies with selection bias were included but analysed separately.

DATA EXTRACTION

Data extracted on prevalence of hypertension, proteinuria and reduced renal function using standardised form. Meta-analysis was performed to calculate weighted mean prevalence.

RESULTS

903 articles were retrieved from our search; 14 studies met the inclusion criteria: 1 prospective randomised controlled trial; 8 prospective observational studies; and 5 retrospective cross-sectional studies. From 928 children with clinically confirmed ADPKD, 20% (95% CI 15% to 27%) were hypertensive. The estimated prevalence of proteinuria in children with ADPKD is 20% (8 studies; 95% CI 9% to 40%) while reduced renal function occurred in 8% (5 studies; 95% CI 2% to 26%).

LIMITATIONS

Studies showed a high degree of methodological heterogeneity (I²=73.4%, τ²=0.3408, p<0.0001). Most studies did not use ambulatory blood pressure (BP) monitoring to diagnose hypertension.

CONCLUSIONS

In this meta-analysis we estimate 20% of children with ADPKD have hypertension. In the population, many children with ADPKD are not under regular follow-up and remain undiagnosed. We recommend that all children at risk of ADPKD have regular BP measurement.

Long-Term Outcomes in Patients with Very-Early Onset Autosomal Dominant Polycystic Kidney Disease

BACKGROUND

Long-term clinical outcomes in children with very-early onset (VEO; diagnosis in utero or within the first 18 months of life) autosomal dominant polycystic kidney disease (ADPKD) are currently not well understood. We conducted a longitudinal retrospective cohort study to assess the association between VEO status and adverse clinical outcomes.

METHODS

Seventy patients with VEO-ADPKD matched (by year of birth, sex and race/ethnicity) to 70 patients with non-VEO-ADPKD who participated in research at the University of Colorado were studied. Kaplan-Meier survival analysis was performed. The predictor was VEO status, and outcomes were progression to end-stage renal disease (ESRD), development of hypertension, progression to estimated glomerular filtration rate (eGFR <90 ml/min/1.73 m2), glomerular hyperfiltration (eGFR ≥140 ml/min/1.73 m2) and height-adjusted total kidney volume (htTKV) measured by MRI ≥600 ml/m.

RESULTS

Median follow-up was until 16.0 years of age. There were only 4 ESRD events during the follow-up period, all in the VEO group (p < 0.05). VEO patients were more likely to develop hypertension (hazard ratio, HR 3.15, 95% CI 1.86-5.34; p < 0.0001) and to progress to eGFR <90 ml/min/1.73 m2 (HR 1.97, 95% CI 1.01-3.84; p < 0.05) than non-VEO patients. There was no difference between groups in the development of glomerular hyperfiltration (HR 0.89, 95% CI 0.56-1.42; p = 0.62). There were only 7 patients who progressed to htTKV ≥600 ml/m, 4 in the VEO group and 3 in the non-VEO group (p < 0.01).

CONCLUSIONS

Several clinical outcomes are worse in patients with VEO-ADPKD compared to non-VEO ADPKD. Children with VEO-ADPKD represent a particularly high-risk group of ADPKD patients.

Proteinuria and hematuria in the neonate

PURPOSE OF REVIEW

Neonatal proteinuria and hematuria while not common can have potentially devastating consequences if left undiagnosed and untreated. It is important to distinguish between inherited and acquired causes of proteinuria to initiate appropriate and timely treatment. With regards to hematuria, it is critical to identify true hematuria from pseudo-hematuria to balance between thorough investigation and unnecessary laboratory work up. This review provides an overview of the common causes of hematuria and proteinuria in a neonate.

RECENT FINDINGS

The identification of genetic mutations in nephrotic syndrome has improved our understanding of the role of various proteins that play an important role in maintaining the glomerular filtration barrier. With the advancement in our ability to provide care for extreme premature neonates, the incidence of acute kidney injury has increased in these neonates along with proteinuria and hematuria.

SUMMARY

Persistent proteinuria after neonatal acute kidney injury would be of interest in regards to the risk of developing future chronic kidney disease and hypertension.

The Role of G-Protein-Coupled Receptor Proteolysis Site Cleavage of Polycystin-1 in Renal Physiology and Polycystic Kidney Disease

Polycystin-1 (PC1) plays an essential role in renal tubular morphogenesis, and PC1 dysfunction causes human autosomal dominant polycystic kidney disease. A fundamental characteristic of PC1 is post-translational modification via cleavage at the juxtamembrane GPCR proteolysis site (GPS) motif that is part of the larger GAIN domain. Given the considerable biochemical complexity of PC1 molecules generated in vivo by this process, GPS cleavage has several profound implications on the intracellular trafficking and localization in association with their particular function. The critical nature of GPS cleavage is further emphasized by the increasing numbers of PKD1 mutations that significantly affect this cleavage process. The GAIN domain with the GPS motif therefore represents the key structural element with fundamental importance for PC1 and might be polycystic kidney disease’s (PKD) Achilles’ heel in a large spectrum of PKD1 missense mutations. We highlight the central roles of PC1 cleavage for the regulation of its biogenesis, intracellular trafficking and function, as well as its significance in polycystic kidney disease.

Comprehensive PKD1 and PKD2 Mutation Analysis in Prenatal Autosomal Dominant Polycystic Kidney Disease

Prenatal forms of autosomal dominant polycystic kidney disease (ADPKD) are rare but can be recurrent in some families, suggesting a common genetic modifying background. Few patients have been reported carrying, in addition to the familial mutation, variation(s) in polycystic kidney disease 1 (PKD1) or HNF1 homeobox B (HNF1B), inherited from the unaffected parent, or biallelic polycystic kidney and hepatic disease 1 (PKHD1) mutations. To assess the frequency of additional variations in PKD1, PKD2, HNF1B, and PKHD1 associated with the familial PKD mutation in early ADPKD, these four genes were screened in 42 patients with early ADPKD in 41 families. Two patients were associated with de novo PKD1 mutations. Forty patients occurred in 39 families with known ADPKD and were associated with PKD1 mutation in 36 families and with PKD2 mutation in two families (no mutation identified in one family). Additional PKD variation(s) (inherited from the unaffected parent when tested) were identified in 15 of 42 patients (37.2%), whereas these variations were observed in 25 of 174 (14.4%, P=0.001) patients with adult ADPKD. No HNF1B variations or PKHD1 biallelic mutations were identified. These results suggest that, at least in some patients, the severity of the cystic disease is inversely correlated with the level of polycystin 1 function.

Fetal imaging prompts maternal diagnosis: autosomal dominant polycystic kidney disease

Autosomal dominant polycystic kidney disease (ADPKD) is a common inherited disorder. Ultrasound (US) findings can include enlarged echogenic kidneys in utero and cysts in multiple organs in adults. Though a highly penetrant disease, due to varied clinical expression and the typical late onset of symptoms, reproductive-aged women may not know their carrier status. We present two cases in which fetal US findings suggested ADPKD and additional evaluation identified likely maternal ADPKD as well.

[Pathophysiology, epidemiology, clinical presentation, diagnosis and treatment options for autosomal dominant polycystic kidney disease]

Autosomal dominant polycystic kidney disease (ADPKD) is the leading genetic cause of end-stage renal disease (ESRD) worldwide. Its prevalence is evaluated according to studies and population between 1/1000 and 1/4000 live births and it accounts for 6 to 8% of incident ESRD patients in developed countries. ADPKD is characterized by numerous cysts in both kidneys and various extrarenal manifestations that are detailed in this review. Clinico-radiological and genetic diagnosis are also discussed. Mutations in the PKD1 and PKD2 codifying for polycystin-1 (PC-1) and polycystin-2 (PC-2) are responsible for the 85 and 15% of ADPKD cases, respectively. In primary cilia of normal kidney epithelial cells, PC-1 and PC-2 interact forming a complex involved in flow- and cilia-dependant signalling pathways where intracellular calcium and cAMP play a central role. Alteration of these multiple signal transduction pathways leads to cystogenesis accompanied by dysregulated planar cell polarity, excessive cell proliferation and fluid secretion, and pathogenic interactions of epithelial cells with an abnormal extracellular matrix. The mass effect of expanding cyst is responsible for the decline in glomerular filtration rate that occurs late in the course of the disease. For many decades, the treatment for ADPKD aims to lessen the condition's symptoms, limit kidney damage, and prevent complications. Recently, the development of promising specific treatment raises the hope to slow the growth of cysts and delay the disease. Treatment strategies targeting cAMP signalling such as vasopressin receptor antagonists or somatostatin analogs have been tested successfully in clinical trials with relative safety. Newer treatments supported by preclinical trials will become available in the next future. Recognizing early markers of renal progression (clinical, imaging, and genetic markers) to identify high-risk patients and multidrug approaches with synergistic effects may provide new opportunities for the treatment of ADPKD.

Autosomal dominant polycystic kidney disease: the changing face of clinical management

Autosomal dominant polycystic kidney disease is the most common inherited kidney disease and accounts for 7-10% of all patients on renal replacement therapy worldwide. Although first reported 500 years ago, this disorder is still regarded as untreatable and its pathogenesis is poorly understood despite much study. During the past 40 years, however, remarkable advances have transformed our understanding of how the disease develops and have led to rapid changes in diagnosis, prognosis, and treatment, especially during the past decade. This Review will summarise the key findings, highlight recent developments, and look ahead to the changes in clinical practice that will likely arise from the adoption of a new management framework for this major kidney disease.

Spanish guidelines for the management of autosomal dominant polycystic kidney disease

Autosomal dominant polycystic kidney disease (ADPKD) is the most frequent cause of genetic renal disease and accounts for 6-10% of patients on renal replacement therapy (RRT). 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 consensus statement 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 found were 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 RRT and management of children with ADPKD. Recommendations on specific ADPKD therapies are not provided since no drug has regulatory approval for this indication.

Looking at the (w)hole: magnet resonance imaging in polycystic kidney disease

Inherited cystic kidney diseases, including autosomal dominant polycystic kidney disease (ADPKD) and autosomal recessive polycystic kidney disease (ARPKD), are the most common monogenetic causes of end-stage renal disease (ESRD) in children and adults. While ARPKD is a rare and usually severe pediatric disease, the more common ADPKD typically shows a slowly progressive course leading to ESRD in adulthood. At the present time there is no established disease-modifying treatment for either ARPKD or ADPKD. Various therapeutic approaches are currently under investigation, such as V2 receptor antagonists, somatostatins, and mTOR inhibitors. Renal function remains stable for decades in ADPKD, and thus clinically meaningful surrogate markers to assess therapeutic efficacy are needed. Various studies have pointed out that total kidney volume (TKV) is a potential surrogate parameter for disease severity in ADPKD. Recent trials have therefore measured TKV by magnet resonance imaging (MRI) to monitor and to predict disease progression. Here, we discuss novel insights on polycystic kidney disease (PKD), the value of MRI, and the measurement of TKV in the diagnosis and follow-up of PKD, as well as novel emerging therapeutic strategies for ADPKD.

Similar renal outcomes in children with ADPKD diagnosed by screening or presenting with symptoms

Autosomal dominant polycystic kidney disease (ADPKD) in children is sometimes considered to be a benign condition, with morbidity manifesting in adulthood. Therefore, diagnostic screening of children at risk is controversial. The aim of our study was to to compare the manifestations of ADPKD in children diagnosed by postnatal ultrasound (US) screening versus those presenting with symptoms. This was a retrospective chart review of children with ADPKD assessed in a single centre between 1987 and 2007. Age and reason for diagnosis were noted, and children were separated into two groups: (1) those diagnosed on the basis of family-based screening; (2) those presenting with a symptom. The two groups were compared for renal size, number of cysts, estimated glomerular filtration rate (eGFR), the presence of hypertension and microalbuminuria. In the 47 children with ADPKD (21 females) from 33 families who satisfied the enrollment criteria, mean (standard deviation) age at referral and last follow-up was 7.2 (4.4) and 12.9 (5.1) years, respectively, and the mean follow-up duration was 5.7 (3.6) years. Diagnosis was based on postnatal US screening in 31 children, whereas 16 were diagnosed after presenting with symptoms. The proportions of children with nephromegaly, hypertension, microalbuminuria and decreased eGFR, respectively, were similar in both groups. Based on these results, we conclude that renal-related morbidities, including hypertension and microalbuminia, do occur in children with ADPKD and at a similar frequency in those diagnosed after presenting with symptoms and those diagnosed upon postnatal screening. We suggest that at-risk children should have regular checks to detect hypertension. Moreover, affected children may benefit from novel therapies to minimise cystic disease progression.

[Autosomal dominant polycystic kidney disease: light at the end of the tunnel?]

Autosomal dominant polycystic kidney disease, characterized by numerous cysts in both kidneys, is the most frequent, potentially lethal monogenic disorder. Its prevalence is evaluated between 1/400 and 1/1000 live births and it accounts for 7 to 8 % of end-stage renal disease in developed countries. As yet, the pathogenesis of this disease is not fully understood and there is no specific treatment available. Nevertheless, in the last few years, fundamental and clinical research has been highly efficient in these fields. The purpose of this review is to update the practical implications of this research in terms of clinical manifestations, diagnosis and treatment.

[Cystic and hyperechogenic kidneys in children]

Thanks to prenatal ultrasound scan, cystic kidneys, as well as obstructive uropathies, are the most frequent renal anomalies identified during pregnancy. They should be recognized because of genetic and clinical implications. The most frequent are autosomal dominant and recessive polycystic kidney diseases, followed by renal developmental anomalies linked to TCF2 gene. Renal cysts are also observed in other hereditary diseases or multiple malformation syndromes (tuberosis sclerosis, Meckel-Grubber syndrome, Oro-facial digital type 1 syndrome...). The diagnosis is based on a sonographic and morphological analysis of renal abnormalities, on the search for family histories and extra-renal manifestations. A better classification of these patients allows tailor-made follow-up and care improvement.

Evidence of extraordinary growth in the progressive enlargement of renal cysts

BACKGROUND AND OBJECTIVES

In autosomal dominant polycystic kidney disease, cysts derived from tubules are detected at birth by ultrasound (threshold for detection >7.0 mm); thus, fetal cyst growth rates must exceed 2300%/yr. In adults, the combined renal cyst component enlarges at approximately 12%/yr by growth of individual cysts. To explore this discrepancy, the growth rates of individual cysts were determined in adult polycystic kidneys.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Diameter, volume, and growth rates of individual cysts were measured by magnetic resonance in 30 individual cysts in three adult patients over a span of 3 years. Results were confirmed in 22 cysts measured in five patients by computed tomography over a span of 11 years.

RESULTS

Mean cyst diameters were 20.4 +/- 9.9 mm (range 7.1 to 40.5 mm) at baseline and 25.8 +/- 15.6 mm (range 7.8 to 49.6 mm) after 3 years. Mean cyst volumes, determined by manual segmentation and summation of magnetic resonance cross sections, were 8.7 +/- 12.9 cm(3) (0.3 to 43.3 cm(3)) and 24.2 +/- 66.3 cm(3) (0.3 to 364.8 cm(3)) after 3 years. Mean cyst growth rates ranged from 6.9 to 23.9%/yr; the maximum growth rate was 71.1%/yr, far less than required to develop a 7-mm diameter cyst in utero. Results were similar in 22 cysts examined by computed tomography.

CONCLUSIONS

It was concluded that renal cysts detected by ultrasound in newborns must have grown at exuberant rates in utero; thereafter, expansion appears to proceed at much slower rates.

The diagnostic value of ultrasound in cystic kidney diseases

Renal cysts in childhood can be found in a variety of diseases, which can be congenital or acquired, or renal cysts may be part of a multiorgan disease or restricted to the kidneys only. Ultrasonography is the first-line diagnostic tool and is informative in many cases. However, there is a broad spectrum in the sonographic appearance of renal cysts, and family or genetic studies, a search for extrarenal organ involvement, or additional imaging modalities may be required to make a definitive diagnosis. The aim of this article is to summarize the diagnostic potential and limitations of ultrasonography and depict typical examples of the most important cystic entities.

Autosomal dominant polycystic kidney disease: the last 3 years

Autosomal dominant polycystic kidney disease is the most prevalent, potentially lethal monogenic disorder. It has large inter- and intra-familial variability explained to a large extent by its genetic heterogeneity and modifier genes. An increased understanding of its underlying genetic, molecular, and cellular mechanisms and a better appreciation of its progression and systemic manifestations have laid out the foundation for the development of clinical trials and potentially effective therapies. The purpose of this review is to update the core of knowledge in this area with recent publications that have appeared during 2006-2009.

Genotype-phenotype correlation in children with autosomal dominant polycystic kidney disease

Adults with autosomal dominant polycystic kidney disease (ADPKD) and PKD1 mutations have a more severe disease than do patients with PKD2 mutations. The aim of this study was to compare phenotypes between children with mutations in the PKD1/PKD2 genes. Fifty PKD1 children and ten PKD2 children were investigated. Their mean age was similar (8.6 +/- 5.4 years and 8.9 +/- 5.6 years). Renal ultrasound was performed, and office blood pressure (BP), ambulatory BP, creatinine clearance and proteinuria were measured. The PKD1 children had, in comparison with those with PKD2, significantly greater total of renal cysts (13.3 +/- 12.5 vs 3.0 +/- 2.1, P = 0.004), larger kidneys [right/left kidney length 0.89 +/- 1.22 standard deviation score (SDS) vs 0.17 +/- 1.03 SDS, P = 0.045, and 1.19 +/- 1.42 SDS vs 0.12 +/- 1.09 SDS, P = 0.014, successively] and higher ambulatory day-time and night-time systolic BP (day-time/night-time BP index 0.93 +/- 0.10 vs 0.86 +/- 0.05, P = 0.021 and 0.94 +/- 0.07 vs 0.89 +/- 0.04, P = 0.037, successively). There were no significant differences in office BP, creatinine clearance or proteinuria. Prenatal renal cysts (14%), hypertension defined by ambulatory BP (27%) and enlarged kidneys (32%) were observed only in the PKD1 children. This is the first study on genotype-phenotype correlation in children with ADPKD. PKD1 children have more and larger renal cysts, larger kidneys and higher ambulatory BP than do PKD2 children. Renal cysts and enlarged kidneys detected prenatally are highly specific for children with PKD1.

Treatment of autosomal dominant polycystic kidney disease (ADPKD): the new horizon for children with ADPKD

Polycystic kidney disease (PKD) is the most common inherited renal disorder. Patients with PKD remain clinically asymptomatic for decades, while significant anatomic and physiologic systemic changes take place. Sequencing of the responsible genes and identification of their protein products have significantly expanded our understanding of the pathophysiology of PKD. The molecular basis for cystogenesis is being unraveled, leading to new targets for therapy and giving hope to millions of people suffering from PKD. This has direct implications for children with PKD with regard to screening for the disease and identification of high-risk individuals. In this article we provide a review of the clinical manifestations in children with autosomal dominant polycystic kidney disease (ADPKD), the genetic and molecular basis for the disease, and a concise review of potential therapies being evaluated.

Autosomal Dominant Polycystic Kidney Disease: Time for a Change?

Diagnosis and treatment of autosomal dominant polycystic kidney disease (ADPKD) is rapidly changing. Cellular pathways that involve the polycystins are being mapped and involve the primary cilium, intracellular calcium and cAMP regulation, and the mammalian target of rapamycin (mTOR) pathway. With the use of new imaging approaches, earlier diagnosis of hepatic cystic disease is possible, and measurement of kidney and cystic growth as well as kidney blood flow is possible over relatively short periods. PKD gene type, gender, proteinuria, and the presence of hypertension relate to the rate of kidney growth in ADPKD. On the basis of risk factors for progression to ESRD and the pathogenic roles that intracellular cAMP and mTOR play in cystogenesis, novel therapies are now being tested, including maximal inhibition of the renin-angiotensin system, inhibition of renal intracellular cAMP using vasopressin V2 receptor antagonists, and somatostatin analogues, as well as inhibitors of mTOR. This review addresses the current understanding of the pathogenesis and the natural history of ADPKD; accuracy and reliability of diagnostic approaches in utero, childhood, and adulthood; the value of reliable magnetic resonance imaging to measure disease progression early in the course of ADPKD; and novel therapeutic approaches that are being evaluated in ADPKD.