Prenatal diagnosis of autosomal dominant polycystic kidney disease (PKD1) presenting in utero and prognosis for very early onset disease

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.

Kidney Measurement and Glomerular Filtration Rate Evolution in Children with Polycystic Kidney Disease

Autosomal dominant polycystic kidney disease (ADPKD) is an inherited disorder characterized by renal tubular cystic dilatations. The cysts can develop anywhere along the nephron, and over time the cystic dilatation leads to kidney enlargement. On the other hand, the cysts begin to reduce the number of functional nephrons as a consequence of cystic expansion that further contributes to the decline in renal function over the years. The pressure exerted by the dilated cysts leads to compensatory mechanisms that further contribute to the decline in renal function. These structural changes are responsible of glomerular hyperfiltration states, albuminuria, proteinuria, and hematuria. However, the presentation of ADPKD varies in children, from a completely asymptomatic child with incidental ultrasound detection of cysts to a rapidly progressive disease. There have been reports of early onset ADPKD in children younger than 2 years that showed a more rapid decline in renal function. ADPKD is caused by a mutation in PKD1 and PKD2 genes. Today, the PKD1 gene mutation seems to account for up to 85% of the cases worldwide, and it is associated with worse renal outcomes. Individuals with PKD2 gene mutation seem to present a milder form of the disease, with a more delayed onset of end-stage kidney disease. The cardinal sign of ADPKD is the presence of renal cysts during renal ultrasound. The current guidelines provide clinicians the recommendations for genetic testing in children with a positive family history. Given that the vast majority of children with ADPKD present with normal or supra-normal kidney function, we explored the glomerular filtration rates dynamics and the renal ultrasound-adjusted percentiles. In total, 14 out of 16 patients had kidney percentiles over 90%. The gene mutations were equally distributed among our cohort. In addition, we compared the modified Schwartz formula to the quadratic equation after adjusting the serum creatinine measurements. It seems that even though children with ADPKD have enlarged kidneys, the renal function is more likely normal or near normal when the quadratic estimation of glomerular filtration rate is used (qGFR tended to be lower, 111.95 ± 12.43 mL/min/1.73 m2 when compared to Schwartz eGFR 126.28 ± 33.07 mL/min/1.73 m2, p = 0.14). Also, when the quadratic equation was employed, not even a single patient reached the glomerular hyperfiltration threshold. The quadratic formula showed that glomerular filtration rates are linear or slightly decreasing after 1 year of follow-up (quadratic ΔeGFR = -0.32 ± 5.78 mL/min/1.73 m2), as opposed to the Schwartz formula that can falsely classify children in a hyperfiltration state (ΔeGFR = 7.51 ± 19.46 mL/min/1.73 m2), p = 0.019.

Autosomal dominant and autosomal recessive polycystic kidney disease: hypertension and secondary cardiovascular effect in children

Autosomal dominant (ADPKD) and autosomal recessive (ARPKD) polycystic kidney disease are the most widely known cystic kidney diseases. They are significantly different from each other in terms of genetics and clinical manifestations. Hypertension is one of the main symptoms in both diseases, but the age of onset and secondary cardiovascular complications are significantly different. Most ARPKD children are hypertensive in the first year of life and need high doses of hypertensive drugs. ADPKD patients with a very early onset of the disease (VEOADPKD) develop hypertension similarly to patients with ARPKD. Conversely, a significantly lower percentage of patients with classic forms of ADPKD develops hypertension during childhood, although probably more than originally thought. Data published in the past decades show that about 20%–30% of ADPKD children are hypertensive. Development of hypertension before 35 years of age is a known risk factor for more severe disease in adulthood. The consequences of hypertension on cardiac geometry and function are not well documented in ARPKD due to the rarity of the disease, the difficulties in collecting homogeneous data, and differences in the type of parameters evaluated in different studies. Overall, left ventricular hypertrophy (LVH) has been reported in 20%–30% of patients and does not always correlate with hypertension. Conversely, cardiac geometry and cardiac function are preserved in the vast majority of hypertensive ADPKD children, even in patients with faster decline of kidney function. This is probably related to delayed onset of hypertension in ADPKD, compared to ARPKD. Systematic screening of hypertension and monitoring secondary cardiovascular damage during childhood allows initiating and adapting antihypertensive treatment early in the course of the disease, and may limit disease burden later in adulthood.

Genetic diagnosis of common fetal renal abnormalities detected on prenatal ultrasound

OBJECTIVES

This retrospective study aimed to investigate the correlations between phenotypes of fetal renal abnormalities on prenatal ultrasound and genetic aetiologies detected using chromosomal microarray analysis (CMA) and whole-exome sequencing (WES).

METHODS

Fetuses with renal abnormalities were subjected to CMA and were further analysed by WES when CMA-negative. The detection rates for chromosomal abnormalities and monogenic variants among different types of isolated renal abnormalities and those with extrarenal abnormalities (non-isolated cases) were determined and compared.

RESULTS

CMA detected chromosomal abnormalities in 78 of 577 fetuses (13.52%). WES detected monogenic variants in 31 of 160 fetuses (19.38%) that had non-diagnostic CMA results. In cases of isolated hyperechogenic kidney, polycystic kidney disease, and multicystic dysplastic kidney, the detection rates of copy number variants (CNVs) by CMA and monogenic variants by WES were not significantly different (P > 0.05). However, monogenic variants were more frequently detected than CNVs when kidney abnormalities were accompanied by reduced amniotic fluid (P < 0.05). Other renal abnormalities identified on prenatal ultrasound had different detection rates.

CONCLUSIONS

Our findings contribute to the overall knowledge of genetic variants associated with prenatally identified renal anomalies and may aid in decision making regarding prenatal genetic testing options for affected pregnancies. This article is protected by copyright. All rights reserved.

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.

Neonatal polycystic kidney disease: a novel variant

Polycystic kidney disease (PKD) is a condition typified by multiple renal cysts and renal enlargement. Classification is usually determined by mode of inheritance-autosomal dominant PKD (ADPKD) or autosomal recessive PKD (ARPKD). ARPKD frequently presents in fetal life, but here we report a rare case of a family with two siblings diagnosed with ADPKD manifesting in utero with novel genetic findings. During the first pregnancy, enlarged cystic kidneys were noted at the gestational age (GA) of 18 weeks, which became progressively larger and anyhdramnios ensued by GA of 25 weeks. The couple opted to terminate the pregnancy. The second pregnancy similarly presented with bilateral enlarged cystic kidneys, but amniotic fluid remained normal throughout and she delivered at GA of 36 weeks. Genetic testing revealed the fetus to be heterozygous in AD PKD1, which is known to cause ADPKD and heterozygous for a hypomorphic allele for ADPKD of uncertain significance. The fetus was also found to be heterozygous in the AR PKHD1 gene with a variant not previously described in the literature. Where fetal features consistent with ARPKD are identified in the setting of familial ADPKD, this fetal manifestation of ADPKD, resulting from combined variants in the PKD1 gene, should be considered.

Cardiac Involvement in Autosomal Dominant Polycystic Kidney Disease

Cardiovascular disorders are the main complication in autosomal dominant polycystic kidney disease (ADPKD). contributing to both morbidity and mortality. This review considers clinical studies unveiling cardiovascular features in patients with ADPKD. Additionally, it focuses on basic science studies addressing the dysfunction of the polycystin proteins located in the cardiovascular system as a contributing factor to cardiovascular abnormalities. In particular, the effects of polycystin proteins’ deficiency on the cardiomyocyte function have been considered.

Management of antenatally detected kidney malformations

Congenital anomalies of the kidneys and the urinary tract (CAKUT) are one of the most common sonographically identified antenatal malformations. Dilatation of the renal pelvis accounts for the majority of cases, but this is usually mild rather than an indicator of obstructive uropathy. Other conditions such as small through large hyperechogenic and/or cystic kidneys present a significant diagnostic dilemma on routine scanning. Accurate diagnosis and prediction of prognosis is often not possible without a positive family history, although maintenance of adequate amniotic fluid is usually a good sign. Both pre- and postnatal genetic screening is possible for multiple known CAKUT genes but less than a fifth of non-syndromic sporadic cases have detectable monogenic mutations with current technology. In utero management options are limited, with little evidence of benefit from shunting of obstructed systems or installation of artificial amniotic fluid. Often outcome hinges on associated cardiac, neurological or other abnormalities, particularly in syndromic cases. Hence, management centres on a careful assessment of all anomalies and planning for postnatal care. Early delivery is rarely indicated since this exposes the baby to the risks of prematurity in addition to their underlying CAKUT. Parents value discussions with a multidisciplinary team including fetal medicine and paediatric nephrology or urology, with neonatologists to plan perinatal care and clinical geneticists for future risks of CAKUT.

Clinical presentation and outcome of autosomal dominant polycystic kidney disease in Nigeria

INTRODUCTION

Autosomal Dominant Polycystic Kidney Disease (ADPKD) is presumably rare in Africa. Knowledge about the disease in Nigeria is limited as demonstrated by scanty articles on the subject.

OBJECTIVES

To determine the pattern of clinical presentation and outcome of ADPKD among ADPKD patients.

METHOD

ADPKD subjects were prospectively studied between January 1996 and December 2010. Their demographics, clinical and investigation parameters were documented. Dependency on dialysis, renal transplant and death were the final outcomes.

RESULTS

Forty one patients (M:F=1.3:1) with mean age of 48.6±4.6 years were studied. ADPKD was diagnosed at 2.73 cases per annum. Family history of ADPKD and hypertension were present in 56.1% and 82.9% respectively. Their mean systolic and diastolic blood pressures were 166.9 ±23.6 and 104 ±21.2 respectively.Nocturia (78.0%) and loin pain (68.3%) were the most common presenting symptoms. Liver cysts (31.7%) and aortic regurgitation (22.0%) were the predominant extra-renal manifestations.Twenty three (56.1%) received haemodialysis; no renal transplantation. Death rate was 51.2%. Presence of uraemia and intra-cerebral aneurysm contributed significantly to mortality.

CONCLUSION

ADPKD may not be so rare in Nigeria. Awareness campaign to change attitude of family members to screening and further studies using newer criteria for diagnosis of ADPKD should be conducted.

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.

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

Autosomal dominant polycystic kidney disease (ADPKD) is the most common hereditary renal disorder. It is characterized by the development of renal cysts and kidney enlargement and ultimately leads to renal failure typically in the sixth decade of life. Although most patients are asymptomatic until well into adulthood, renal cysts develop much earlier, often in utero. Significant renal anatomic and cystic expansion typically occurs before clinical manifestations in children and young adults with AKPKD. The cyst burden detected by imaging represents the minority of cyst burden, and renal and cardiovascular abnormalities are the most common manifestations in children with ADPKD. Here we review the molecular pathogenesis of ADPKD, discuss the screening, diagnosis and clinical manifestations of this renal disorder in childhood and adolescents and review treatment options and potential therapies currently being tested.

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.

Neonatal hypertension

Neonatal hypertension (HT) is a frequently under reported condition and is seen uncommonly in the intensive care unit. Neonatal HT has defined arbitrarily as blood pressure more than 2 standard deviations above the base as per the age or defined as systolic BP more than 95% for infants of similar size, gestational age and postnatal age. It has been diagnosed long back but still is the least studied field in neonatology. There is still lack of universally accepted normotensive data for neonates as per gestational age, weight and post-natal age. Neonatal HT is an important morbidity that needs timely detection and appropriate management, as it can lead to devastating short-term effect on various organs and also poor long-term adverse outcomes. There is no consensus yet about the treatment guidelines and majority of treatment protocols are based on the expert opinion. Neonate with HT should be evaluated in detail starting from antenatal, perinatal, post-natal history, and drug intake by neonate and mother. This review article covers multiple aspects of neonatal hypertension like definition, normotensive data, various etiologies and methods of BP measurement, clinical features, diagnosis and management.

Autosomal dominant polycystic kidney disease in children

PURPOSE OF REVIEW

Autosomal dominant polycystic kidney disease (ADPKD) is the most common hereditary renal disease, affecting one in 500 individuals. The cardinal manifestation of ADPKD is progressive cystic dilatation of renal tubules with kidney enlargement and progression to end-stage renal disease in approximately half of cases by 60 years of age. Although previously considered a condition of adults, it is clear that children and young adults are subject to the complications of ADPKD.

RECENT FINDINGS

It has been increasingly recognized that interventions early in life are necessary in order to confer the best long-term outcome in this common condition. Therefore, it is imperative for pediatricians to recognize the manifestations and complications of this disease. Until recently ADPKD management focused on general principles of chronic kidney disease. However, several recent clinical trials in children and adults with ADPKD have focused on disease-specific therapies.

SUMMARY

This review will highlight the clinical manifestations, diagnosis, and appropriate management of ADPKD in childhood and will review recent relevant clinical trials in children and adults with this condition.

Effect of pravastatin on total kidney volume, left ventricular mass index, and microalbuminuria in pediatric autosomal dominant polycystic kidney disease

BACKGROUND AND OBJECTIVES

In autosomal dominant polycystic kidney disease (ADPKD), progressive kidney cyst formation commonly leads to ESRD. Because important manifestations of ADPKD may be evident in childhood, early intervention may have the largest effect on long-term outcome. Statins are known to slow progressive nephropathy in animal models of ADPKD. This randomized double-blind placebo-controlled phase III clinical trial was conducted from 2007 to 2012 to assess the effect of pravastatin on height-corrected total kidney volume (HtTKV) and left ventricular mass index (LVMI) by magnetic resonance imaging (MRI) and urine microalbumin excretion (UAE) in children and young adults with ADPKD.

DESIGNS, SETTING, PARTICIPANTS, & MEASUREMENTS

There were 110 pediatric participants with ADPKD and normal kidney function receiving lisinopril who were randomized to treatment with pravastatin or placebo for a 3-year period with evaluation at 0, 18, and 36 months. The primary outcome variable was a ≥ 20% change in HtTKV, LVMI, or UAE over the study period.

RESULTS

Ninety-one participants completed the 3-year study (83%). Fewer participants receiving pravastatin achieved the primary endpoint compared with participants receiving placebo (69% versus 88%; P=0.03). This was due primarily to a lower proportion reaching the increase in HtTKV (46% versus 68%; P=0.03), with similar findings observed between study groups for LVMI (25% versus 38%; P=0.18) and UAE (47% versus 39%; P=0.50). The percent change in HtTKV adjusted for age, sex, and hypertension status over the 3-year period was significantly decreased with pravastatin (23% ± 3% versus 31% ± 3%; P=0.02).

CONCLUSIONS

Pravastatin is an effective agent to slow progression of structural kidney disease in children and young adults with ADPKD. These findings support a role for early intervention with pravastatin in this condition.

Hypertension in infancy: diagnosis, management and outcome

Advances in the ability to identify, evaluate, and care for infants with hypertension, coupled with advances in the practice of Neonatology, have led to an increased awareness of hypertension in modern neonatal intensive care units. This review will present updated data on blood pressure values in neonates, with a focus on the changes that occur over the first days and weeks of life in both term and preterm infants. Optimal blood pressure measurement techniques as well as the differential diagnosis of hypertension in the neonate and older infants will be discussed. Recommendations for the optimal immediate and long-term evaluation and treatment, including potential treatment parameters, will be presented. We will also review additional information on outcome that has become available over the past decade.

Glomerular hyperfiltration and renal progression in children with autosomal dominant polycystic kidney disease

BACKGROUND AND OBJECTIVES

The purpose of this study was to determine whether glomerular hyperfiltration (GH) occurring early in autosomal dominant polycystic kidney disease (ADPKD) is indicative of more rapid disease progression in children.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

One hundred eighty children with ADPKD (ages 4 to 18 years) with normal renal function were examined by renal ultrasound. Renal volume was calculated using a standard formula for a modified ellipsoid. Creatinine clearance was calculated from serum creatinine and 24-hour urine creatinine. GH was defined as creatinine clearance ≥140 ml/min per 1.73 m(2).

RESULTS

Thirty-two children had GH (mean age 11.4 ± 3.6 years) and 148 had normal renal function (mean age 10.8 ± 3.9 years). Patients with GH at baseline demonstrated an increased rate of total renal volume growth (β: rate of change = +19.3 ± 10.8 cm(3)/year) over 5 years compared with those without GH at baseline (β = -4.3 ± 7.7 cm(3)/year), P = 0.008. Those with GH at baseline experienced a faster decline in creatinine clearance in subsequent years (β = -5.0 ± 0.8 ml/min per 1.73 m(2) per year) compared with those without GH at baseline (β = +1.0 ± 0.4 ml/min per 1.73 m(2) per year), P < 0.0001.

CONCLUSIONS

This study revealed that occurrence of GH in ADPKD children is associated with a significantly faster decline in renal function and higher rate of kidney enlargement over time. GH combined with the increased renal volume may therefore be used as an early marker for a more severe progression of ADPKD in children.

Diagnosis and management of childhood polycystic kidney disease

A number of syndromic disorders have renal cysts as a component of their phenotypes. These disorders can generally be distinguished from autosomal dominant polycystic kidney disease (ADPKD) and autosomal recessive polycystic kidney disease (ARPKD) by imaging studies of their characteristic, predominantly non-renal associated abnormalities. Therefore, a major distinction in the differential diagnosis of enlarge echogenic kidneys is delineating ARPKD from ADPKD. ADPKD and ARPKD can be diagnosed by imaging the kidney with ultrasound, computed tomography, or magnetic resonance imaging (MRI), although ultrasound is still the method of choice for diagnosis in utero and in young children due to ease of use, cost, and safety. Differences in ultrasound characteristics, the presence or absence of associated extrarenal abnormalities, and the screening of the parents >40 years of age usually allow the clinician to make an accurate diagnosis. Early diagnosis of ADPKD and ARPKD affords the opportunity for maximal anticipatory care (i.e. blood pressure control) and in the not-too-distant future, the opportunity to benefit from new therapies currently being developed. If results are equivocal, genetic testing is available for both ARPKD and ADPKD. Specialized centers are now offering preimplantation genetic diagnosis and in vitro fertilization for parents who have previously had a child with ARPKD. For ADPKD patients, a number of therapeutic interventions are currently in clinical trial and may soon be available.

Fetal genitourinary anomalies--a pictorial review with postnatal correlation

An accurate diagnosis of fetal genitourinary abnormality is essential because some genitourinary abnormalities are associated with pulmonary hypoplasia, which ultimately affects the neonatal outcome. Adrenal masses are rare; however, presence of any lesion located at the superior pole of the kidney should raise the possibility of an adrenal mass. Fetal genital anomalies are rare as well and some of the most difficult to diagnose. A combination and pattern of findings allows for specific diagnosis of renal tract abnormalities. This article reviews the imaging appearance of fetal genitourinary abnormalities with perinatal imaging correlation where available.

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.

Renal ultrasonographic evaluation in children at risk of autosomal dominant polycystic kidney disease

BACKGROUND

To date, there are no criteria for diagnosing autosomal dominant polycystic kidney disease (ADPKD) in at-risk children 15 years or younger.

STUDY DESIGN

Longitudinal (retrospective cohort study).

SETTING & PARTICIPANTS

420 children (mean age, 8.3 +/- 4.2 years) with a family history of ADPKD were studied.

MEASUREMENTS

Renal ultrasonography was performed for cyst detection. Urine protein was measured using two 24-hour urine collections. Glomerular filtration rate was calculated using the Schwartz formula. Blood pressure measurements were performed in the arm with the highest blood pressure, using an appropriate cuff size. Standard 2-dimensional and Doppler echocardiography was performed for measuring left ventricular mass index.

PREDICTORS

None.

OUTCOME

Presence of renal cysts.

RESULTS

Renal cysts were detected in 193 children and no cysts were detected in 227 children. In children with renal cysts, 150 had bilateral and 43 had unilateral cysts. Children with bilateral cysts had larger kidneys and more hypertension than children with unilateral or no cysts. Follow-up in 77 children 15 years or younger showed bilateral cysts in 14 and unilateral cysts in 4 of the children who had no detectable renal cysts using ultrasonography at baseline. Similar follow-up of 26 children 15 years or younger with unilateral cysts detected at baseline showed bilateral cysts in 17 children using ultrasonography. By 15 years of age, 181 patients in the total group of 420 showed bilateral cysts. Overall, 193 of 304 children (63.4%) who had follow-up at any age developed bilateral cysts detected using ultrasonography.

LIMITATIONS

Follow-up unavailable for all participants.

CONCLUSION

The present results in 420 at-risk children with ADPKD 15 years or younger detected bilateral renal cysts using ultrasonography in 181 of the children who had a family history of this genetic disease.

Renal volume, renin-angiotensin-aldosterone system, hypertension, and left ventricular hypertrophy in patients with autosomal dominant polycystic kidney disease

The relationship between renal volume and hypertension in autosomal dominant polycystic kidney disease (ADPKD) occurs in childhood. Hypertension is associated not only with increased kidney volume but also with significantly increased left ventricular mass index. Moreover, this increase in left ventricular mass index occurs in children who have ADPKD with borderline hypertension (75th to 95th percentile) and is prevented with angiotensin-converting enzyme inhibitor (ACEI) monotherapy. Progression from borderline to overt hypertension (> or =95th percentile) occurs during a 5-yr follow-up in approximately 50% of children with ADPKD and borderline hypertension. Renal cyst enlargement in ADPKD in adults is associated with stimulation of both the circulating and intrarenal renin-angiotensin-aldosterone system. In addition to hypertension, the resultant angiotensin in ADPKD is a pivotal factor in cyst proliferation and expansion, increased sympathetic and endothelin activity, oxidant injury, and fibrosis. There is a close correlation between the level of hypertension, left ventricular hypertrophy, deterioration of GFR, and the progressive enlargement of the cystic kidneys in adult ADPKD. Randomized clinical investigation indicates that ACEI and a BP goal of 120/80 mmHg are associated in a 7-yr study to reverse left ventricular hypertrophy. The effect of renin-angiotensin-aldosterone system inhibition with dual blockade, ACEI and angiotensin receptor antagonists, on renal volume and kidney function is under study in the Halt Progression of Polycystic Kidney Disease (HALT PKD) trial.

The diversity of PKD1 alleles: implications for disease pathogenesis and genetic counseling

Rossetti et al. identify non- and incompletely penetrant alleles of PKD1. Although such alleles are well recognized in other human mendelian disorders, they have not been associated with autosomal dominant polycystic kidney disease (ADPKD). These alleles produce atypical, mild, or severe disease depending on whether they are inherited in the heterozygous or homozygous state or in trans with another mutation, providing an intriguing potential mechanism for the considerable phenotypic variability seen in families with ADPKD.

Prospective change in renal volume and function in children with ADPKD

BACKGROUND AND OBJECTIVES

Autosomal dominant polycystic kidney disease (ADPKD) is a progressive hereditary disorder affecting children and young adults. Early intervention may be necessary to significantly affect the long-term consequences of this disease.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

The authors conducted a 5-yr randomized clinical trial to assess the effect of BP control with angiotensin-converting enzyme inhibition (ACEI) on disease progression in 85 children and young adults with ADPKD. Study groups were determined by subject BP, including hypertension (BP >or= 95th percentile), borderline hypertension (BP 75 to 95th percentile), and severe ADPKD (BP <or=75th percentile with > 10 renal cysts). The primary outcome variable was renal volume by ultrasound, with secondary outcome variables including left ventricular mass index (LVMI) and microalbuminuria. In secondary analysis, the authors compared results between hypertensive and normotensive groups.

RESULTS

The authors were not able to demonstrate a significant effect of ACEI on renal growth in young subjects with ADPKD. Hypertensive children were at particular risk for increases in renal volume and LVMI and decreased renal function as compared with the other study groups, and borderline hypertensive children were at high risk to develop hypertension over time. However, ACEI treatment was associated with stable renal function and LVMI in this group of children.

CONCLUSIONS

Close monitoring of cardiovascular and renal status is indicated in ADPKD children with hypertension or borderline hypertension. In contrast to effects in hypertensive ADPKD children, ACEI treatment in normotensive or borderline hypertensive ADPKD children may prevent the development of increased LVMI and deterioration in renal function.

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.

Incompletely penetrant PKD1 alleles suggest a role for gene dosage in cyst initiation in polycystic kidney disease

Autosomal dominant polycystic kidney disease (ADPKD) caused by mutations in PKD1 is significantly more severe than PKD2. Typically, ADPKD presents in adulthood but is rarely diagnosed in utero with enlarged, echogenic kidneys. Somatic mutations are thought crucial for cyst development, but gene dosage is also important since animal models with hypomorphic alleles develop cysts, but are viable as homozygotes. We screened for mutations in PKD1 and PKD2 in two consanguineous families and found PKD1 missense variants predicted to be pathogenic. In one family, two siblings homozygous for R3277C developed end stage renal disease at ages 75 and 62 years, while six heterozygotes had few cysts. In the other family, the father and two children with moderate to severe disease were homozygous for N3188S. In both families homozygous disease was associated with small cysts of relatively uniform size while marked cyst heterogeneity is typical of ADPKD. In another family, one patient diagnosed in childhood was found to be a compound heterozygote for the PKD1 variants R3105W and R2765C. All three families had evidence of developmental defects of the collecting system. Three additional ADPKD families with in utero onset had a truncating mutation in trans with either R3277C or R2765C. These cases suggest the presence of incompletely penetrant PKD1 alleles. The alleles alone may result in mild cystic disease; two such alleles cause typical to severe disease; and, in combination with an inactivating allele, are associated with early onset disease. Our study indicates that the dosage of functional PKD1 protein may be critical for cyst initiation.

Increased left ventricular mass in children with autosomal dominant polycystic kidney disease and borderline hypertension

Autosomal dominant polycystic kidney disease (ADPKD) is a common hereditary condition that may be diagnosed in utero. Our goal was to evaluate symptoms of ADPKD in children, including left ventricular mass index (LVMI), renal volume, renal function and microalbuminuria in relation to systolic and diastolic blood pressure. Eighty-five children were stratified by blood pressure into three cohorts: hypertensive (95th percentile and over), borderline hypertensive (75-95th percentile) and normotensive (75th percentile and below). There were no differences in gender, age, height, renal function, or microalbuminuria between the groups. Both the hypertensive and borderline hypertensive children had a significantly higher LVMI than normotensive children, with no significant difference between hypertensive and borderline hypertensive groups. There was a significant correlation between renal volume and both systolic and diastolic blood pressures in all subjects. Renal volume in hypertensive children was significantly larger than in the borderline hypertensive group, with no significant difference between normotensive and borderline hypertensive groups. These findings show that an increase in LVMI may be detected earlier than an increase in renal volume in children with ADPKD and borderline hypertension, suggesting that close monitoring of cardiac status is indicated in these children.

Determinants of renal volume in autosomal-dominant polycystic kidney disease

The Consortium of Radiologic Imaging Studies of Polycystic Kidney Disease (CRISP) recently showed that renal enlargement in autosomal-dominant polycystic kidney disease mimicked exponential growth. We determined the effects of cyst initiation rate, total number, and growth rate on the time-dependent change of total cyst volume (TCV). Mathematical models with equations integrating cyst surface area, volume, and an invariant growth rate constant were used to compute the time-dependent change in volume of solitary and multiple cysts. Multiple expanding cysts increased TCV in an exponential-like pattern even when individual cysts formed at different rates or exhibited different but constant growth rates. TCV depended on the rate of cyst initiation and on the total number of cysts; however, the compounding effect of exponential-like growth was the most powerful determinant of long-term cyst expansion. Extrapolation of TCV data plots for individual subjects back to an age of 18 predicted TCV values within an established range. We conclude that cysts started early in life were the main contributor to eventual TCV while their growth rate primarily determined renal size; although the rate of formation and the ultimate number of cysts also contributed. The good fit between the exponential models and the extrapolated CRISP data indicates that the TCV growth rate is a defining trait for individual patients and may be used as a prognostic marker.

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.

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

The use of prenatal ultrasonography has resulted in increased numbers of fetuses being diagnosed with autosomal dominant polycystic kidney disease (ADPKD), but the long-term prognosis is still not well-known. Between 1981 and 2006 we followed 26 consecutive children with enlarged hyperechoic kidneys detected between the 12th week of pregnancy and the first day of life (Day 1) as well as one affected parent. Three other fetuses were excluded following the termination of the pregnancy. The mother was the transmitting parent in 16 of the 26 children (ns, p=0.1). Clinical features that presented during follow-up were oligoamnios (5/26), neonatal pneumothorax (3/26), pyelonephritis (5/26), gross hematuria (2/26), hypertension (5/26), proteinuria (2/26) and chronic renal insufficiency (CRI) (2/26). At the last follow-up (mean duration of follow-up: 76 months; range: 0.5-262 months), 19 children (mean age: 5.5 years) were asymptomatic, five (mean age: 8.5 years) had hypertension, two (mean age: 9.7 years) had proteinuria and two (mean age: 19 years) had CRI. Children presenting enlarged kidneys postnatally tended to have more clinical manifestations than their counterparts who did not. Of 25 siblings of the patients, seven had renal cysts; these were detected during childhood in five siblings and in utero in two siblings. In conclusion, prognosis is favourable in most children with prenatal ADPKD, at least during childhood. The sex of the transmitting parent is not a risk factor of prenatal ADPKD. A high proportion of siblings develop early renal cysts. Abnormalities visualized by ultrasonography appear to be associated to more clinical manifestations.

Differential diagnosis of fetal hyperechogenic cystic kidneys unrelated to renal tract anomalies: A multicenter study

OBJECTIVES

To identify important factors in the differential diagnosis of renal cysts associated with hyperechogenic kidneys.

METHODS

This was a retrospective multicenter study. We identified 93 fetuses presenting between 1990 and 2002 with hyperechogenic kidneys and which had a diagnosis of nephropathy confirmed later. We analyzed retrospectively the prenatal ultrasound findings of those fetuses which were found sonographically to have renal cysts.

RESULTS

Of the 93 fetuses presenting with hyperechogenic kidneys and with a later diagnosis of nephropathy, there were 28 with autosomal dominant polycystic kidney disease (ADPKD), 31 with autosomal recessive polycystic kidney disease (ARPKD), 11 with Bardet-Biedl syndrome, nine with Meckel-Gruber syndrome, six with Ivemark II syndrome, one with Jarcho-Levin syndrome, one with Beemer syndrome and one with Meckel-like syndrome. One third of the fetuses (30/93) had renal cysts. Cystic characteristics (size, location, number) were not very useful for diagnosis; more useful was diagnosis of an associated malformation. Three (11%) of the fetuses with ADPKD had cysts, as did nine (29%) of those with ARPKD, three (27%) of those with Bardet-Biedl syndrome, all (100%) of those with Meckel-Gruber syndrome, three (50%) of those with Ivemark II syndrome, and each of the three cases with other syndromes (Jarcho-Levin, Beemer and Meckel-like syndromes). None of the cases with trisomy 13 had cysts. There were no associated malformations in the 12 cases with renal cysts and polycystic kidney disease; the other 18 cases with renal cysts were associated with malformations that were often specific, such as polydactyly in Bardet-Biedl and Beemer syndromes, occipital defect and Dandy-Walker malformation in Meckel-Gruber or Meckel-Gruber-like syndromes, and thoracic and/or vertebral abnormalities in Jarcho-Levin and Beemer syndromes.

CONCLUSION

Renal cysts associated with hyperechogenic kidneys are not rare. The clue to diagnosis is the demonstration of an associated malformation. If no malformation is found, the main diagnosis remains polycystic kidney disease, i.e. ARPKD or ADPKD.

Pax2 gene dosage influences cystogenesis in autosomal dominant polycystic kidney disease

Mutations in PKD1 cause dominant polycystic kidney disease (PKD), characterized by large fluid-filled kidney cysts in adult life, but the molecular mechanism of cystogenesis remains obscure. Ostrom et al. [Dev. Biol., 219, 250-258 (2000)] showed that reduced dosage of Pax2 caused increased apoptosis, and ameliorated cystogenesis in Cpk mutant mice with recessive PKD. Pax2 is expressed in condensing metanephrogenic mesenchyme and arborizing ureteric bud, and plays an important role in kidney development. Transient Pax2 expression during fetal kidney mesenchyme-to-epithelial transition, as well as in nascent tubules, is followed by marked down-regulation of Pax2 expression. Here, we show that in humans with PKD, as well as in Pkd1(del34/del34) mutant mice, Pax2 was expressed in cyst epithelial cells, and facilitated cyst growth in Pkd1(del34/del34) mutant mice. In Pkd1(del34/del34) mutant kidneys, the expression of Pax2 persisted in nascent collecting ducts. In contrast, homozygous Pkd1(del34/del34) fetal mice carrying mutant Pax2 exhibited ameliorated cyst growth, although reduced cystogenesis was not associated with increased apoptosis. Pax2 expression was attenuated in nascent collecting ducts and absent from remnant cysts of Pkd1(del34/del34)/Pax2(1Neu/+) mutant mice. To investigate whether the Pkd1 gene product, Polycystin-1, regulates Pax2, MDCK cells were engineered constitutively expressing wild-type Pkd1; Pax2 protein levels and promoter activity were both repressed in MDCK cells over-expressing Pkd1, but not in cells without transgenic Pkd1. These data suggest that polycystin-1-deficient tubular epithelia persistently express Pax2 in ADPKD, and that Pax2 or its pathway may be an appropriate target for the development of novel therapies for ADPKD.

Autosomal-dominant polycystic kidney disease in infancy and childhood: progression and outcome

BACKGROUND

The natural history of autosomal-dominant polycystic kidney disease (ADPKD) has not been well described in children and infants.

METHODS

The present study analyzed the characteristics of 46 ADPKD children diagnosed before 18 months of life (VEO) and 153 children diagnosed between 18 months of age and 18 years of age (non-VEO).

RESULTS

VEO children had more cysts and larger renal volumes than non-VEO children when adjusted for age. In both VEO and non-VEO children, the presence of signs or symptoms at the time of diagnosis as well as the presence of hematuria or proteinuria at the study visit were associated with larger renal volumes. Children diagnosed early (VEO) or diagnosed due to signs or symptoms were also more likely to have high blood pressure. Two VEO children and no non-VEO children reached end-stage renal disease during follow-up.

CONCLUSION

In contrast to many published case reports suggesting the occurrence of early end-stage renal disease in VEO children, the results of the present study were much more optimistic. Over 90% of the VEO children maintained preserved renal function well into childhood.

Fetal hyperechogenic kidney with normal amniotic fluid volume: a diagnostic dilemma

OBJECTIVE

To determine the prognostic value of sonographically detected fetal hyperechogenic kidneys with normal amniotic fluid volume.

METHODS

Seven cases of hyperechogenic fetal kidneys were identified by sonography over a 7-year period (1996--2002). Increased renal echogenicity was diagnosed when the renal parenchyma was of greater echogenicity than adjacent liver tissue. Amniotic fluid volume was measured by the semiquantitative sonographic technique known as the amniotic fluid index (AFI).

RESULTS

Three of the live-born infants had autosomal dominant polycystic kidney disease and one had autosomal recessive polycystic kidney. In the remainder, autopsy study revealed multifocal renal dysplasia in two cases and normal kidneys in one.

CONCLUSIONS

Increased renal echogenicity with normal amniotic fluid volume in a fetus without other anomalies is a difficult diagnostic dilemma. Although it is usually indicative of renal parenchymal disease with possible renal failure after birth or in early childhood, in some cases, it represents a normal variant. .

Disruption of polycystin-1 function interferes with branching morphogenesis of the ureteric bud in developing mouse kidneys

The polycystic kidney disease (PKD1) gene-encoded protein, polycystin-1, is developmentally regulated, with highest expression levels seen in normal developing kidneys, where it is distributed in a punctate pattern at the basal surface of ureteric bud epithelia. Overexpression in ureteric epithelial cell membranes of an inhibitory pMyr-GFP-PKD1 fusion protein via a retroviral (VVC) delivery system and microinjection into the ureteric bud lumen of embryonic day 11 mouse metanephric kidneys resulted in disrupted branching morphogenesis. Using confocal quantitative analysis, significant reductions were measured in the numbers of ureteric bud branch points and tips, as well as in the total ureteric bud length, volume and area, while significant increases were seen as dilations of the terminal branches, where significant increases in outer diameter and volumes were measured. Microinjection of an activating 5TM-GFP-PKD1 fusion protein had an opposite effect and showed significant increases in ureteric bud length and area. These are the first studies to experimentally manipulate polycystin-1 expression by transduction in the embryonic mouse kidney and suggest that polycystin-1 plays a critical role in the regulation of epithelial morphogenesis during renal development.

Autosomal dominant polycystic kidney disease (ADPKD, MIM 173900, PKD1 and PKD2 genes, protein products known as polycystin-1 and polycystin-2)

Autosomal dominant polycystic kidney disease (ADPKD) is a common inherited nephropathy affecting over 1:1000 of the worldwide population. It is a systemic condition with frequent hepatic and cardiovascular manifestations in addition to the progressive development of renal cysts that eventually result in loss of renal function in the majority of affected individuals. The diagnosis of ADPKD is typically made using renal imaging despite the identification of mutations in PKD1 and PKD2 that account for virtually all cases. Mutations in PKD1 are associated with more severe clinical disease and earlier onset of renal failure. Most PKD gene mutations are loss of function and a 'two-hit' mechanism has been demonstrated underlying focal cyst formation. The protein products of the PKD genes, the polycystins, form a calcium-permeable ion channel complex that regulates the cell cycle and the function of the renal primary cilium. Abnormal cilial function is now thought to be the primary defect in several types of PKD including autosomal recessive polycystic kidney disease and represents a novel and exciting mechanism underlying a range of human diseases.

Prenatal sonographic patterns in autosomal dominant polycystic kidney disease: a multicenter study

OBJECTIVE

To determine whether a specific prenatal sonographic pattern can be identified for autosomal dominant polycystic kidney disease (ADPKD) and if so whether it would be helpful in orienting complementary analysis, properly counseling parents and adapting pregnancy management.

METHODS

A retrospective multicenter study was conducted in four prenatal diagnostic centers. The records of fetuses with a prenatal ultrasound examination revealing abnormal kidneys and with a final diagnosis of ADPKD were analyzed. Ultrasound analysis included: amount of amniotic fluid, bladder size, renal length, presence or absence of renal cysts and size of renal pelves, and was focused on parenchyma echogenicity and status of corticomedullary differentiation. Postnatal follow-up was reviewed.

RESULTS

Of the 27 patients included in the study, 25 had hyperechogenic renal cortex and 20 had hypoechogenic medulla resulting in increased corticomedullary differentiation (CMD). In six cases, the medulla was hyperechogenic leading to absent or decreased CMD. One patient had normal cortical echogenicity and CMD. Renal cysts were present during the prenatal period in four patients (at 22 weeks in one case and after 30 weeks in three cases). In 12 patients, the cysts appeared after birth (within the first 6 months of postnatal life in 10 cases and by the age of 1 year in two cases). Elevated blood pressure was observed in only two cases and moderate chronic renal failure in one case.

CONCLUSION

We have described the sonographic presentation in fetuses with ADPKD: moderately enlarged hyperechogenic kidneys with increased CMD. Although not specific to ADPKD, these findings should prompt familial screening. Other prenatal sonographic features (absent or decreased CMD and cortical cysts) are less frequent.

Phenotypic heterogeneity in pediatric autosomal dominant polycystic kidney disease at first presentation: a single-center, 20-year review

BACKGROUND

The presentation of autosomal dominant polycystic kidney disease (ADPKD) in childhood provides an insight into comorbidities and potential areas for interventions and investigation.

METHODS

Phenotypic heterogeneity at the time of first presentation was studied with respect to age of diagnosis, mode of presentation, parental inheritance pattern, renal function, associated hypertension, and hyperlipidemia. Fifty-five children (median age of presentation, 8.7 years; 27% < 1 year) with ADPKD from 44 families followed up between March 1983 and March 2003 were reviewed. The diagnosis was based on family history and ultrasound confirmation of cysts. Progression of renal disease was followed over the study period (mean duration of follow-up, 4.9 years).

RESULTS

A family history of ADPKD was known at presentation in 89%, which precipitated the screening diagnostic imaging in 59% of these children. Maternal inheritance was displayed in 51%, whereas 5% had no known family history of ADPKD. Bilateral renal findings were present in 78%. Hypertension (>95(th) percentile for age) was present in 22%, and hyperlipidemia was present in 54%. Renal function was not significantly diminished in 98% of patients with creatinine clearance > or =3rd percentile for age, and 7% had persistent proteinuria (>150 mg/d). No subjects had hepatic, splenic, or pancreatic cysts on ultrasound scan. A subpopulation of 10 patients had features of ADPKD dating back to prenatal ultrasound scans. All prenatal cases were characterized by bilateral renal findings, 90% had a known family history of ADPKD at the time of presentation, and 89% of these patients displayed maternal inheritance. Follow-up studies showed a persistence of hyperlipidemia despite pharmacotherapeutic treatment of hypertension, infrequent proteinuria, and sustained renal function in most patients.

CONCLUSION

The results of this study show that many children at the time of first presentation have a significant prevalence of modifiable risk factors: hypertension, proteinuria, and hyperlipidemia, in the face of normal renal function. The results also show a unique presentation existing in prenatal subjects.

Fetal renal anomalies and genetic syndromes

Renal abnormalities are some of the commonest and most easily detectable anomalies on ultrasound. Many are an isolated finding but the prognosis may be altered considerably by the detection of other anomalies which could indicate a genetic disorder or syndrome. It is often easier to detect presupposed anomalies and the purpose of this article is to introduce and discuss those syndromes that may present with a renal abnormality on ultrasound. Common renal findings are presented with the range of additional anomalies that should be sought and suggested diagnostic tests. It should be remembered that although for many genetic conditions specific mutation analysis is now available, this usually requires pre-pregnancy investigations. Furthermore, in some cases the definitive diagnosis may not be suspected until post mortem. By this time it may be too late to establish a cell line to confirm the suspicion using laboratory methods. It is therefore important to take tissue samples antenatally where possible, or at delivery, as postnatal samples may have a high culture failure rate.

Dysplastic and polycystic kidneys: diagnosis, associations and management

Cystic and bright kidneys can pose a significant diagnostic dilemma when discovered as an incidental finding at the time of a routine fetal ultrasound scan. There are diverse aetiologies with equally variable implications for the prognosis in the affected fetus, and for future pregnancies. Accurate antenatal diagnosis in the absence of any positive family history is often not possible and a team approach to management (to include the fetal medicine specialist, paediatric nephrologist or urologist, geneticists and in some cases, pathologist) is essential. In this review we will attempt to describe the embryology and aetiology of these conditions and suggest an approach to management.

Prenatal diagnosis and management of abnormalities in the urologic system

We have reviewed the prenatal diagnosis and management of abnormalities in the urologic system. Urologic anomalies may be caused by embryologic aberrations, genetic disease, or a nonrandom association with other structural abnormalities. There is a wide range of prognoses, depending on the cause and the impact of the anomaly on the production of amniotic fluid. Management focuses on obtaining an accurate prenatal diagnosis, providing appropriate counseling, and ensuring the proper surveillance or treatment before and after birth.

Cystic kidney disease presenting in infancy

AIM

The clinical, histological and imaging findings of 12 children with ultrasound features of severe renal cystic disease presenting in the first year of life were reviewed.

METHODS AND RESULTS

Two children had cystic dysplasia and four had autosomal dominant polycystic disease. Two had a malformation syndrome, one a variant of Meckel syndrome and the other Bardet Biedl syndrome. One had autosomal recessive polycystic disease and in three there was no final diagnosis. Intravenous urography gave non-specific information. In six cases clinical findings combined with imaging established a diagnosis. Diagnosis was established by biopsy in two and gave supportive evidence in one. Outlook for renal function is variable. One child has had a transplant and one is on dialysis awaiting a transplant. Three have a degree of renal failure and one has died. Six have normal renal function. Renal cystic disease is the common pathway for a heterogeneous group of disorders as shown in these children.

CONCLUSION

It is emphasized that a specific diagnosis could not be made from the renal sonographic appearances alone, nor could any prognostic implications for renal function be made. Contrast retention on intravenous urography was also insufficiently specific to be of value. Ultrasound of the parents was the most useful imaging procedure and should be done in all cases.

Renal cystic disease

Renal cystic diseases constitute the most common genetic cause for end-stage renal disease in children and young adults. Recently, there has been rapid progress regarding the identification or chromosomal localization of some of the responsible disease genes. Studies of the respective gene products and of related animal models have led to new insights into the pathophysiology of these disorders. In this review, very recent developments are discussed as they pertain to molecular genetic diagnosis, the understanding of pathophysiology, and potential novel therapeutic approaches to renal cystic diseases.