The renal lesion of the Laurence-Moon-Biedl syndrome

Bardet-Biedl syndrome: Delayed diagnosis in a 14-year-old child with end-stage renal disease

Bardet-Biedl syndrome (BBS) is a rare autosomal recessive ciliopathic disorder. Because of its low prevalence and wide spectrum of clinical features, many patients remain undiagnosed. We report a case of a 14-year-old boy with a typical phenotype of BBS who remains undiagnosed until the development of end-stage renal disease.

Modelling renal defects in Bardet-Biedl syndrome patients using human iPS cells

Bardet-Biedl syndrome (BBS) is a ciliopathy with pleiotropic effects on multiple tissues, including the kidney. Here we have compared renal differentiation of iPS cells from healthy and BBS donors. High content image analysis of WT1-expressing kidney progenitors showed that cell proliferation, differentiation and cell shape were similar in healthy, BBS1, BBS2, and BBS10 mutant lines. We then examined three patient lines with BBS10 mutations in a 3D kidney organoid system. The line with the most deleterious mutation, with low BBS10 expression, expressed kidney marker genes but failed to generate 3D organoids. The other two patient lines expressed near normal levels of BBS10 mRNA and generated multiple kidney lineages within organoids when examined at day 20 of organoid differentiation. However, on prolonged culture (day 27) the proximal tubule compartment degenerated. Introducing wild type BBS10 into the most severely affected patient line restored organoid formation, whereas CRISPR-mediated generation of a truncating BBS10 mutation in a healthy line resulted in failure to generate organoids. Our findings provide a basis for further mechanistic studies of the role of BBS10 in the kidney.

Retinitis pigmentosa and deafness

Seventeen patients with retinitis pigmentosa (RP) have been investigated audiologically. Of 9 found to have a significant hearing loss, 6 were examples of Usher's syndrome; these patients had a cochlear pattern of hearing loss. The other 3 were examples of Senior's syndrome, Kearne-Sayre syndrome and Lawrence-Moon-Biedle syndrome respectively. Two of these patients had absent stapedius reflexes. It is suggested that patients with different RP-deafness syndromes may have lesions in different parts of the auditory system.

Mutations in DCDC2 (doublecortin domain containing protein 2) in neonatal sclerosing cholangitis

BACKGROUND & AIMS

Neonatal sclerosing cholangitis (NSC) is a severe neonatal-onset cholangiopathy commonly leading to liver transplantation (LT) for end-stage liver disease in childhood. Liver biopsy findings histopathologically resemble those in biliary atresia (BA); however, in NSC extrahepatic bile ducts are patent, whilst in BA their lumina are obliterated. NSC is commonly seen in consanguineous kindreds, suggesting autosomal recessive inheritance.

METHODS

From 29 NSC patients (24 families) identified, DNA was available in 24 (21 families). Thirteen (7 male) patients (12 families) of consanguineous parentage were selected for whole exome sequencing. Sequence variants were filtered for homozygosity, pathogenicity, minor allele frequency, quality score, and encoded protein expression pattern.

RESULTS

Four of 13 patients were homozygous and two were compound heterozygous for mutations in the doublecortin domain containing 2 gene (DCDC2), which encodes DCDC2 protein and is expressed in cholangiocyte cilia. Another 11 patients were sequenced: one (with one sibling pair) was compound heterozygous for DCDC2 mutations. All mutations were protein-truncating. In available liver tissue from patients with DCDC2 mutations, immunostaining for human DCDC2 and the ciliary protein acetylated alpha-tubulin (ACALT) showed no expression (n=6) and transmission electron microscopy found that cholangiocytes lacked primary cilia (n=5). DCDC2 and ACALT were expressed in NSC patients without DCDC2 mutations (n=22). Of the patients carrying DCDC2 mutations, one died awaiting LT; five came to LT, of whom one died 2years later. The other 4 are well.

CONCLUSION

Among 24 NSC patients with available DNA, 7 had mutations in DCDC2 (6 of 19 families). NSC patients in substantial proportion harbour mutations in DCDC2. Their disease represents a novel liver-based ciliopathy.

LAY SUMMARY

Neonatal sclerosing cholangitis (NSC) is a rare genetic form of liver disease presenting in infancy. Through next generation sequencing we identified mutations in the gene encoding for doublecortin domain containing 2 (DCDC2) protein in a group of NSC children. DCDC2 is a signalling and structural protein found in primary cilia of cholangiocytes. Cholangiocytes are the cells forming the biliary system which is the draining system of the liver.

Phenotypic expression of Bardet-Biedl syndrome in patients homozygous for the common M390R mutation in the BBS1 gene

PURPOSE

To characterize the phenotype of Bardet-Biedl syndrome (BBS) patients homozygous for the BBS1 M390R mutation.

METHODS

Three patients [PT1, F, 27 years old (yo) at last examination, 14-year follow-up (F/U) PT2, F, 15-yo PT3, M, 15-yo, both 1-year F/U] underwent eye exams, Goldmann visual fields (GVFs), dark- (DA) and light-adapted (LA) electroretinograms (ERGs), spectral domain optical coherence tomography (SD-OCT) and fundus autofluorescence (FAF). Vision and systemic history were also collected.

RESULTS

All patients had night blindness, hyperopic astigmatism, ptosis or mild blepharospasm, foot polydactyly, 5th finger clinodactyly, history of headaches, and variable, diet-responsive obesity. Two had asthma, PT1 was developmentally delayed, PT2 had Asperger-like symptoms, and PT3 had normal cognition. At age 14, acuity was 20/100 in PT1, who had nystagmus since age 2, 20/40 in PT2 and 20/30 in PT3. By 27yo PT1 progressed to 20/320, by 15 yo PT2 was 20/60 and PT3 remained stable. PT1 had well preserved peripheral GVFs, with minimal progression over 10 years of F/U. PT2 and PT3 presented with ring scotomas and I4e<5°. All patients had severe generalized visual sensitivity depression. ERGs were consistently recordable (also rod ERG in PT3 after 60 min DA), but progressed to non-recordable in PT1. Mixed DA ERGs exhibited electronegativity. In PT3, this was partly due to a bleaching effect during bright-flash DA averaging, partly to ON≫OFF LA response compromise. PT2 and 3 had, on SD-OCTs, generalized macular thinning, normal retinal lamination, and widespread photoreceptor outer/inner segment attenuation except foveally, and multiple rings of abnormal FAF configuring a complex bull's eye-pattern. PT1 had macular atrophy. All patients also had peripapillary nerve fiber layer thickening.

CONCLUSIONS

The observed phenotype matches very closely that reported in patients by Azari et al. (IOVS 2006) and in the Bbs1-M390R knock-in mouse model, and expands it to the characterization of important ERG response characteristics that provide insight in the pathogenesis of retinopathy in these patients. Our findings confirm the consistent pathogenicity of the BBS1 M390R mutation.

Phenotypic variability of Bardet-Biedl syndrome: focusing on the kidney

Bardet-Biedl syndrome (BBS) is a multisystemic developmental disorder diagnosed on the basis of the presence of obesity, retinal defects, polydactyly, hypogonadism, renal dysfunction, and learning disabilities. The syndrome is genetically heterogeneous with 14 BBS genes identified to date. Since the cloning of the first gene in 2000, a combination of genetic, in vitro, and in vivo studies have highlighted ciliary dysfunction as a primary cause of BBS pathology. Pleiotropy of ciliopathy phenotypes and complex genetic interactions between causal and modifying alleles of ciliary genes contribute to phenotypic variability. In particular, kidney disease in BBS is clinically heterogeneous, but is now recognized as a cardinal feature and a major cause of mortality in BBS.

Bardet-Biedl syndrome with end-stage kidney disease in a four-year-old Romanian boy: a case report

BACKGROUND

Bardet-Biedl syndrome is a significant genetic cause of chronic kidney disease in children. Kidney abnormalities are a major cause of morbidity and mortality in Bardet-Biedl syndrome, but the onset of end-stage renal disease at an early age and continuous ambulatory peritoneal dialysis, however, are not commonly mentioned in the literature.

CASE PRESENTATION

We present the case of a four-year-old Romanian boy who presented to our department with 'febrile seizures'. After an initial evaluation, we diagnosed our patient as having hypertension, severe anemia and end-stage renal disease. He met the major and minor criteria for the diagnosis of Bardet-Biedl syndrome and underwent continuous ambulatory peritoneal dialysis.

CONCLUSIONS

Close follow-up for renal involvement in patients with Bardet-Biedl syndrome and Alström syndrome from an early age is highly recommended to prevent end-stage renal disease and so renal replacement therapy can be started immediately.

Liver and kidney disease in ciliopathies

Hepatorenal fibrocystic diseases (HRFCDs) are among the most common inherited human disorders. The discovery that proteins defective in the autosomal dominant and recessive polycystic kidney diseases (ADPKD and ARPKD) localize to the primary cilia and the recognition of the role these organelles play in the pathogenesis of HRFCDs led to the term "ciliopathies." While ADPKD and ARPKD are the most common ciliopathies associated with both liver and kidney disease, variable degrees of renal and/or hepatic involvement occur in many other ciliopathies, including Joubert, Bardet-Biedl, Meckel-Gruber, and oral-facial-digital syndromes. The ductal plate malformation (DPM), a developmental abnormality of the portobiliary system, is the basis of the liver disease in ciliopathies that manifest congenital hepatic fibrosis (CHF), Caroli syndrome (CS), and polycystic liver disease (PLD). Hepatocellular function remains relatively preserved in ciliopathy-associated liver diseases. The major morbidity associated with CHF is portal hypertension (PH), often leading to esophageal varices and hypersplenism. In addition, CD predisposes to recurrent cholangitis. PLD is not typically associated with PH, but may result in complications due to mass effects. The kidney pathology in ciliopathies ranges from non-functional cystic dysplastic kidneys to an isolated urinary concentration defect; the disorders contributing to this pathology, in addition to ADPKD and ARPKD, include nephronophithisis (NPHP), glomerulocystic kidney disease and medullary sponge kidneys. Decreased urinary concentration ability, resulting in polyuria and polydypsia, is the first and most common renal symptom in ciliopathies. While the majority of ADPKD, ARPKD, and NPHP patients require renal transplantation, the frequency and rate of progression to renal failure varies considerably in other ciliopathies. This review focuses on the kidney and liver disease found in the different ciliopathies.

Nephronophthisis

Nephronophthisis (NPHP) is an autosomal recessive kidney disorder characterized by chronic tubulointerstitial nephritis and leading to end-stage renal failure. NPHP as a renal entity is often part of a multisystem disorder and has been associated with many syndromes including Joubert syndrome (and related disorders) and Senior-Loken syndrome. Recent molecular genetic advances have allowed identification of several genes underlying NPHP. Most of these genes express their protein products, named nephrocystins, in primary cilial/basal body structures. Some nephrocystins are part of adherens junction and focal adhesion kinase protein complexes. This shared localization suggests that common pathogenic mechanisms within the kidney underlie this disease. Functional studies implicate nephrocystins in planar cell polarity pathways, which may be crucial for renal development and maintenance of tubular architecture.

Asymptomatic renal cell carcinoma as a finding of Bardet Biedl syndrome

Retinitis pigmentosa represents a class of disorders that exhibit dystrophy of the photoreceptors, pigment epithelium, and often systemic abnormalities, Bardet-Biedl syndrome is a form of retinitis pigmentosa that has characteristic non-ocular findings including polydactyly, obesity, learning difficulties, male hypogonadism, and renal anomalies. Though none of these renal anomalies are neoplastic, there is a 17 fold increased risk for renal cell carcinoma in obligate carriers of Bardet-Biedl syndrome. Herein, we describe a case of metastatic renal cell carcinoma discovered in a patient with Bardet-Biedl syndrome.

Bardet-Biedl syndrome: beyond the cilium

The Bardet-Biedl syndrome (BBS) is a significant genetic cause of chronic and end-stage renal failure in children. Despite being a relatively rare recessive condition, BBS has come to prominence during the past few years owing to revelations of primary cilia dysfunction underlying pathogenesis. The study of this multi-system disorder, which includes obesity, cognitive impairment, genito-urinary tract malformations and limb deformities, is beginning to reveal insights into several aspects of mammalian development and organogenesis. Involvement of BBS proteins in disparate pathways such as the non-canonical Wnt and Sonic Hedgehog pathways is highlighting their interplay in disease pathogenesis. Here we review the recent developments in this emerging field, with the emphasis on the renal component of the syndrome and potential future directions.

Antenatal renal sonographic anomalies and postnatal follow-up of renal involvement in Bardet-Biedl syndrome

OBJECTIVES

To describe an antenatal sonographic renal pattern encountered in Bardet-Biedl syndrome, a rare autosomal recessive disorder whose definitive diagnosis is often delayed, and to describe the evolution of the sonographic appearance of the kidneys after birth.

METHODS

Among a large group of fetuses with hyperechoic kidneys, we retrospectively analyzed the prenatal sonographic findings and clinical and postnatal renal sonographic evolution of 11 patients who were found to be affected by Bardet-Biedl syndrome.

RESULTS

All 11 fetuses presented enlarged homogeneously hyperechoic kidneys without corticomedullary differentiation. The diagnosis was established before birth in three fetuses thanks to their familial history. It was confirmed during childhood in the remaining eight based on the development of the classic features of the syndrome. In the postnatal period, the prenatal pattern persisted for a few months in all 11 cases. The sonographic aspects of the kidneys normalized in most cases between 1 and 2 years after birth.

CONCLUSIONS

In affected families, the prenatal appearance of enlarged hyperechoic kidneys without corticomedullary differentiation should prompt a diagnosis of recurrence in the family of Bardet-Biedl syndrome, especially when polydactyly is present. In non-affected families, Bardet-Biedl syndrome should be included in the differential diagnosis whenever such an appearance is discovered in utero. The postnatal evolution of the renal sonographic findings is variable and normalization generally occurs by the age of 2 years.

A review of the literature of Bardet-Biedl disease and report of three cases associated with metabolic syndrome and diagnosed after the age of fifty

Bardet-Biedl syndrome (BBS) is a genetic autosomal-recessive disease (formerly grouped with Laurence-Moon-Biedl syndrome but considered today as a separate entity) characterized by abdominal obesity, mental retardation, dysphormic extremities (syndactyly, brachydactyly or polydactyly), retinal dystrophy or pigmentary retinopathy, hypogonadism or hypogenitalism (limited to male patients) and kidney structural abnormalities or functional impairment. The expression and severity of the various clinical BBS features show inter- and intrafamilial variability. This study focuses on three cases of familial BBS--two sisters and one brother (66, 64 and 51 years of age, respectively)--with the main cardinal findings of the disease plus a classic 'metabolic syndrome' (characterized by abdominal obesity, atherogenic dyslipidaemia, raised blood pressure, insulin resistance with or without glucose intolerance, and prothrombotic risk and proinflammatory states). One female patient (not affected by reproductive dysfunction) had three healthy offspring, while the other two patients were unmarried. Another severely affected brother died at 70 years of age; two other brothers are lean but affected by nephropathy, retinopathy, slight mental retardation, polydactyly, hypertension and thrombotic diseases, and had healthy offspring. BBS is a rather rare but severe syndrome that is often mis- or undiagnosed. Ophthalmologists, endocrinologists and nephrologists should be aware of BBS because of its adverse prognosis--early onset of blindness, associated findings of metabolic syndrome and increased vascular risk, and severe renal impairment (the most frequent cause of reduced survival and death early in life).

Renal cancer and malformations in relatives of patients with Bardet-Biedl syndrome

BACKGROUND

Bardet-Biedl syndrome (BBS) is an autosomal recessive disorder with five loci identified thus far. The spectrum of disease includes diverse malformations of the kidney and lower urinary tract. The incidence of BBS is approximately 1/100,000 with a predicted heterozygote frequency of 1/160, and it has been suggested that heterozygotes are at increased risk of obesity and hypertension.

METHODS

We describe renal disease in relatives of 109 UK BBS patients. Using PCR with fluorescent microsatellite markers we amplified DNA derived from renal tumours of affected parents to determine whether there was loss of heterozygosity at any of four BBS loci and two other gene loci associated with clear cell renal cell carcinoma (CC-RCC).

RESULTS

CC-RCC was diagnosed in three of 180 BBS parents and there was loss of heterozygosity at BBS1 (11q13) in the tumour tissue of one of these subjects. In addition, there was a high incidence of renal agenesis in siblings of BBS patients and two BBS families were identified with apparently dominant inheritance of renal malformations. In one family we were able to demonstrate that renal malformations segregated with the BBS2 locus (16q21).

CONCLUSIONS

Since all parents and two-thirds of siblings of BBS patients must be heterozygous for BBS mutations, our observations may implicate BBS genes in the pathogenesis of both renal cancer and malformations, both disorders of precursor cell growth and differentiation. We suggest these observations may have important implications for screening potential BBS carriers for kidney disease and may lead to a greater understanding of the aetiology of renal disease in the general population.

New criteria for improved diagnosis of Bardet-Biedl syndrome: results of a population survey

Bardet-Biedl syndrome (BBS) is an autosomal recessive condition characterised by rod-cone dystrophy, postaxial polydactyly, central obesity, mental retardation, hypogonadism, and renal dysfunction. BBS expression varies both within and between families and diagnosis is often difficult. We sought to define the condition more clearly by studying 109 BBS patients and their families, the largest population surveyed to date. The average age at diagnosis was 9 years, which is late for such a debilitating condition, but the slow development of the clinical features of BBS probably accounts for this. Postaxial polydactyly had been present in 69% of patients at birth, but obesity had only begun to develop at around 2-3 years, and retinal degeneration had not become apparent until a mean age of 8.5 years. Our study identified some novel clinical features, including neurological, speech, and language deficits, behavioural traits, facial dysmorphism, and dental anomalies. In the light of these features we propose a revision of the diagnostic criteria, which may facilitate earlier diagnosis of this disorder. We present evidence for an overlapping phenotype with the Laurence-Moon syndrome and propose a unifying, descriptive label be adopted (polydactyly-obesity-kidney-eye syndrome).

 We report an increased prevalence of renal malformations and renal cell carcinoma in the unaffected relatives of BBS patients and suggest that these may be a consequence of heterozygosity for BBS genes. Our findings have important implications for the care of BBS patients and their unaffected relatives.

The ocular phenotype of the Bardet-Biedl syndrome. Comparison to non-syndromic retinitis pigmentosa

PURPOSE

To investigate 20 patients affected with Bardet-Biedl (BB) syndrome and compare them to an age-matched group of 70 non-syndromic patients with retinitis pigmentosa (RP) to identify hallmarks peculiar to the BB phenotype.

METHODS

Patients were examined clinically and with functional tests (color vision, kinetic perimetry, electroretinography, ocular motility tests). Fundus findings were numerically graded for statistical purposes.

RESULTS

Recurrent ocular features in BB patients were early and severe reduction of visual acuity, constantly altered color vision, high incidence of strabismus and nystagmus, mild-to-severe atrophic changes of the optic disc, and frequently absent or minimal pigmentary retinal changes. Visual acuity was more closely correlated to optic disc than to macular conditions. These findings were remarkably different from non-syndromic RP.

CONCLUSIONS

This investigation further suggests that retinopathy in BB syndrome has features distinctive from those in non-syndromic RP. The early occurrence of optic disc atrophy in the BB syndrome, even in those patients with healthy maculas, suggests that optic atrophy could often be primary in nature and might play a major role in decreasing central vision in BB patients. Variability of some findings is in line with the documented heterogeneity of the BB syndrome.

The importance of renal impairment in the natural history of Bardet-Biedl syndrome

Bardet-Biedl syndrome is a rare autosomal recessive disease characterized by dysphormic extremities, retinal dystrophy, obesity, hypogenitalism in males, and renal structural abnormalities. Because the clinical outcome of these patients is not well known, 21 families with Bardet-Biedl syndrome (BBS) were studied to determine the natural history of the disease. In a prospective cohort study, 38 patients with the syndrome and 58 unaffected siblings were identified. Patients were studied in 1987 and again in 1993. Age of onset of blindness, hypertension, diabetes, renal impairment, and death was determined. The prevalence of obesity, gonadal dysfunction, and renal structural abnormalities was assessed. All but 5 BBS patients (86%) were legally blind, 26% being blind by the age of 13 years and 50% by 18 years. Eighty-eight percent were above the 90th percentile for height and weight. Twenty-five (66%) patients had hypertension, 25% of BBS patients by age 26 years, and 50% by age 34 years, whereas in the unaffected group, 25% had hypertension by age 49 years (P < 0.0001). Twelve (32%) BBS patients developed diabetes mellitus, compared with none of the unaffected group. Only 2 patients were insulin dependent. Twenty-five percent of BBS patients had diabetes by the age of 35 years. In 12 women of reproductive age, 1 (8%) had primary gonadal failure. In 10 men, 4 had primary testicular failure. Nine (25%) patients developed renal impairment, with 25% of the BBS group affected by the age of 48 years. Imaging procedures of the kidney were performed in 25 patients with normal renal function. Whereas fetal lobulation and calyceal cysts/diverticula/clubbing were characteristic, occurring in 96% of patients, 20% (n = 5) had diffuse and 4% (n = 1) focal cortical loss. Eight patients with BBS died, 3 with end-stage renal failure and 3 with chronic renal failure. On life-table analysis, 25% of BBS patients had died by 44 years, whereas at that age 98% of unaffected siblings were still alive (P < 0.0001). Bardet-Biedl syndrome has an adverse prognosis, with early onset of blindness, obesity, hypertension, and diabetes mellitus. Renal impairment is frequent and an important cause of death. Survival is substantially reduced.

Cardiac abnormalities in the Bardet-Biedl syndrome: echocardiographic studies of 22 patients

The Bardet-Biedl syndrome is an autosomal recessive disorder of polydactyly, obesity, tapetoretinal degeneration, mental retardation, hypogenitalism, and renal involvement. A high incidence of congenital and acquired heart disease was reported in the former "Laurence-Moon-Biedl-Bardet" syndrome. However, since the establishment of the Bardet-Biedl syndrome as a separate clinical entity, cardiac involvement has not been evaluated in this disorder. We have performed echocardiographic studies on 22 patients with the Bardet-Biedl syndrome from three extended, highly inbred Bedouin families. In addition to previously reported congenital heart defects we have observed hypertrophy of the interventricular septum and dilated cardiomyopathy. Our findings of cardiac involvement in 50% of the cases suggest that echocardiographic examination should be included in the clinical evaluation and follow-up of patients with Bardet-Biedl syndrome.

Pediatric renal transplantation in Laurence-Moon-Biedl syndrome

Two cases of renal transplantation in pediatric patients with Laurence-Moon-Biedl syndrome are reported. Immunosuppressive therapy consisted of cyclosporine, prednisone and azathioprine. Renal function has been good but both patients developed morbid obesity.

Cystic kidney dysplasia and polydactyly in 3 sibs with Bardet-Biedl syndrome

Two infants with cystic kidney dysplasia and polydactyly were born to consanguineous parents. One infant died at age 2 months, and the other is currently 3.5 years old. A third pregnancy was terminated following ultrasonographic visualization of large echo-dense fetal kidneys and polydactyly. Although none had apparent brain anomalies, they were considered to represent the Meckel syndrome. Extinguished responses on electroretinography in our 3.5-year-old patient has led to the diagnosis of Bardet-Biedl syndrome. This observation offers an opportunity to revisit the Bardet-Biedl syndrome and provides further evidence that structural renal abnormalities are characteristic of the syndrome. We wish to alert the clinician to the diagnosis of Bardet-Biedl syndrome in patients with infantile cystic kidney dysplasia.

Senior-Loken syndrome. Case reports of two siblings and association with sensorineural deafness

Two siblings with Senior-Loken syndrome are described. The need for a full evaluation of renal function and hearing in children with a retinal dystrophy is emphasised.

Obesity, hypertension, and renal disease in relatives of Bardet-Biedl syndrome sibs

The Bardet-Biedl syndrome is a rare autosomal recessive disorder characterized by pigmentary retinopathy, obesity, polydactyly, hypogonadism, and mental retardation. Renal abnormalities, hypertension, acquired heart disease, and hepatic fibrosis also occur in homozygotes. Two adult Bardet-Biedl sibs, a man with hypertension and cardiomegaly and a woman with biliary cirrhosis, and 75 relatives in 5 generations of the extended family were identified. Hospital records for major illnesses, death certificates, and autopsy reports were examined. The frequent observation of obesity, hypertension, diabetes mellitus, and renal disease in first-degree relatives, obligate gene carriers, and other blood relatives raise the possibility that Bardet-Biedl heterozygotes are also predisposed to these disorders.

Early diagnosis of Bardet-Biedl syndrome

A 3-year-old boy presented with decreased renal function, hypertension, obesity and developmental delay. Evaluation of his kidneys revealed blunting of the calyces and multiple renal cortical cysts. Ophthalmologic evaluation showed no abnormalities on examination but electroretinography showed reduced retinal function suggesting a diffuse retinal disorder. Based on the clinical presentation with the associated abnormalities, the diagnosis of Bardet-Biedl syndrome, a form of the Laurence-Moon-Biedl syndrome was made. This syndrome should be considered and specific diagnostic efforts should be made in pediatric patients who present with renal failure and obesity.

The cardinal manifestations of Bardet-Biedl syndrome, a form of Laurence-Moon-Biedl syndrome

To determine the interfamilial and intrafamilial variation in the expression of the Bardet-Biedl syndrome (a form of Laurence-Moon-Biedl syndrome), we looked for the five recognized features of the disorder (retinal dystrophy, obesity, polydactyly, mental retardation, and hypogonadism), plus possible renal manifestations, in some or all of 32 patients with this disorder. All 28 patients examined had severe retinal dystrophy, but only 2 had typical retinitis pigmentosa. Polydactyly was present in 18 of 31 patients, but syndactyly, brachydactyly, or both were present in all. Obesity was present in all but 1 of 25 patients. Only 13 of 32 patients were considered mentally retarded. Scores on verbal subtests of intelligence were usually lower than scores on performance tasks. Seven of eight men had small testes and genitalia, which was not due to hypogonadotropism. All 12 women studied had menstrual irregularities, and 3 had low serum estrogen levels (1 of these had hypogonadotropism, and 2 had primary gonadal failure). The remaining women who were of reproductive age had endocrinologic evidence of reproductive dysfunction. Diabetes mellitus was present in 9 of 20 patients. Renal structural or functional abnormalities were universal (n = 21), and three patients had end-stage renal failure. We conclude that the characteristic features of Bardet-Biedl syndrome are severe retinal dystrophy, dysmorphic extremities, obesity, renal abnormalities, and (in male patients only) hypogenitalism. Mental retardation, polydactyly, and hypogonadism in female patients are not necessarily present.

Sonographic and urographic correlation in Bardet-Biedl syndrome (formerly Laurence-Moon-Biedl syndrome)

To determine the spectrum of urologic disease and the value of ultrasound as a screening mechanism, renal imaging was performed on 23 patients with Bardet-Biedl syndrome. On intravenous urography (IVU), abnormal calices were present in 22 patients, with communicating cortical cysts/diverticula in 17. Ultrasound detected caliceal or cystic changes in 70%. On IVU, 21 patients had fetal-type lobular outlines that were detected on sonography in 95%. Renal structural abnormalities are characteristic of the Bardet-Biedl syndrome, and are still best imaged by urography.

Visual acuities and dark-adapted thresholds of children with Bardet-Biedl syndrome

We studied the visual acuities and dark-adapted sensitivities of 12 children with Bardet-Biedl syndrome. All except one child, who was seen only once, were tested serially. In the first decade of life, all visual acuities were within 2 octaves of normal. All but two final visual acuities obtained from patients in their second and third decades were more than 2 octaves poorer than normal. Dark-adapted sensitivities of all patients were, or became, significantly less than normal even in those patients whose period of follow-up was limited to the first decade of life. Of the 11 patients measured serially, seven showed decreases in dark-adapted sensitivities of at least 0.5 log unit during the follow-up period, and the last measured sensitivities of all patients were at least 2 log units less than the normal mean.

Retinitis pigmentosa

Retinitis pigmentosa is a clinically and genetically heterogeneous group of hereditary disorders in which there is progressive loss of photoreceptor and pigment epithelial function. The prevalence of retinitis pigmentosa is between 1/3000 and 1/5000 making it one of the most common causes of visual impairment in all age groups. The natural history, differential diagnosis, diagnostic clinical and electrophysiologic findings are reviewed. Generalization about the different genetic subtypes of retinitis pigmentosa are reviewed along with the uses of DNA probes for linkage studies. Syndromes in which retinitis pigmentosa is a manifestation are summarized.

The spectrum of renal disease in Laurence-Moon-Biedl syndrome

To determine the nature, extent, and severity of renal involvement in Laurence-Moon-Biedl syndrome (obesity, mental retardation, polydactyly, hypogonadism, and pigmented retinal dystrophy), we evaluated 20 of 30 patients with the disorder identified from ophthalmologic records in Newfoundland. The mean age was 31 years, and seven were male. All 20 patients had structural or functional abnormalities of the kidneys or both. Three had end-stage renal disease, with two requiring maintenance hemodialysis. The remaining 17 patients had normal serum creatinine values and estimated creatinine clearances. Half the subjects had hypertension. Fourteen of 17 patients could not concentrate urine above 750 mOsm per kilogram of body weight even after vasopressin, whereas all 10 normal controls could. Urinary pH decreased below 5.3 after ammonium chloride administration in all 15 normal controls, but in only 13 of 18 patients. Calyceal clubbing or blunting was evident in 18 of 19 patients studied by intravenous pyelography; 13 patients had calyceal cysts or diverticula. Seventeen of 19 patients had lobulated renal outlines of the fetal type. Four patients had diffuse renal cortical loss, but only two of these had renal insufficiency. We conclude that Laurence-Moon-Biedl syndrome includes the presence of renal abnormalities.

Glomerulonephropathy of Laurence-Moon-Biedl syndrome

A patient with Laurence-Moon-Biedl syndrome and nephrotic range proteinuria is presented. Radiological investigation of the urinary tract revealed clubbed calyces but no evidence of obstruction or vesicoureteric reflux. Renal biopsy revealed occasional sclerotic glomeruli, extensive foot-process fusion and segmental glomerular basement membrane abnormalities with negative immunofluorescence for immunoglobulins and complement. Nephrotic proteinuria responded to steroid therapy but mild proteinuria persisted. The findings were consistent with minimal change nephropathy superimposed on the glomerular lesions of Lawrence-Moon-Biedl syndrome.

Chronic renal failure; an important feature of the Laurence-Moon-Biedl syndrome

Two cases of end stage renal failure occurring in association with the Laurence-Moon-Biedl syndrome are reported. Abnormalities in renal function and morphology are increasingly recognized in these patients in whom uraemia is an important cause of morbidity and early mortality. The presence of renal impairment, occurring as frequently as any of the pentad of features that characterize the syndrome, has important implications for the prognosis and long term management of these patients.

Mesangioproliferative glomerulonephritis associated with retinitis pigmentosa

Two patients with retinitis pigmentosa and glomerulonephritis are described. The patients were unrelated and had identical renal lesions, mesangioproliferative glomerulonephritis. This may not be a chance association, and simple dip-stick urine analysis in patients with primary retinal degenerations may lead to earlier identification of renal disease.

Bardet-Biedl and Laurence-Moon syndromes in a mixed Arab population

In the Arab population of Kuwait of approximately 1.3 million, 26 cases in 15 families were ascertained to have Bardet-Biedl syndrome (20 cases in 13 families) or Laurence-Moon syndrome (6 cases in 2 families). The apparently increased frequency of these interrelated autosomal recessive syndromes in Arabs is discussed in view of the high consanguinity rate and large family size.

Prenatal renal ultrasound of Laurence-Moon-Biedl syndrome

Large echogenic kidneys mimicking infantile polycystic kidneys were seen on prenatal ultrasound examination in a patient subsequently found to be affected by Laurence-Moon-Biedl syndrome.

Ophthalmologic and systemic manifestations of Alström's disease

Alström's syndrome consists of pigmentary retinopathy, diabetes, obesity, normal mental capacity, and sensorineural deafness. The early retinal findings are optic atrophy, salt-and-pepper pigment epithelial abnormalities, and marked vascular attenuation. Later in the disease process, diffuse areas of chorioretinal atrophy and large clumps of pigment develop. Severe visual loss in the first decade is characteristic and is an important point in the differential diagnosis. Clinically evident renal disease is a variable age-related phenomenon, and is probably the most frequent cause of death.

Histopathology of mitochondrial cytopathy and the Laurence-Moon-Biedl syndrome

Clinical and histopathological studies of two patients with distinctly different inherited juvenile retinal dystrophies indicate that the ocular defect in mitochondrial cytopathy involves the underlying pigment epithelium, whereas in the Laurence-Moon-Biedl syndrome the photoreceptor cells are primarily affected.

Renal involvement in the Laurence-Moon-Biedl syndrome. Functional and radiological studies

The renal abnormality of the Laurence-Moon-Biedl syndrome (LMBS) was investigated in six patients. The glomerular filtration rate (CIn) and the effective renal plasma flow (CPAH) were evaluated by standard clearance techniques and the single injection method, and the maximal concentration capacity was estimated by the ddAVP test. The kidney surface area and length were related to the body surface area, as well as the lumbar vertebrae L1-L3, and the relationship with the GFR was studied. All six patients showed renal abnormalities: Five had small kidneys with reduced GFR and concentrating ability, and one had hyperaminoaciduria (but normal kidney size). Two patients developed terminal renal failure (one of them was successfully transplanted), illustrating the progressive character of the renal lesion. Three of the patients had had recurrent urinary tract infections, but the radiological changes of the kidneys were of the same character as in the others (symmetrical and irregular parenchymal reduction, and blunting and clubbing of the calyces). Since renal abnormalities, with considerable risk for progression to terminal renal failure, are common in the LMBS, regular urine cultures and blood pressure measurements are probably of great importance.

Familial juvenile nephronophthisis, Jeune's syndrome, and associated disorders

Fourteen patients with familial juvenile nephronophthisis are described, eight of whom displayed one or more additional disorders. One boy with short limbed dwarfism and an abnormal chest was considered to have Jeune's syndrome; review of the published reports supports the view that nephronophthisis is the principal cause of renal failure in this disorder. Another patient with renal failure and retinitis pigmentosa at presentation developed progressive neurological and neuromuscular impairment leading to the discovery of ragged red fibre disease (mitochondrial cytopathy). Cardiomyopathy was present in this and one other patient. Tapeto-retinal degeneration, hepatic fibrosis, cerebellar ataxia, and oculomotor apraxia were among the other disorders encountered. Three patients presented in extremis with acute heart failure and irreversible oligo-anuria and this complication developed in another child who was already known to have nephronophthisis. Awareness of this disease and its associations is important for early diagnosis and appropriate management.

Cystic kidneys. Genetics, pathologic anatomy, clinical picture, and prenatal diagnosis

According to the classification of Osathanondh and Potter of cystic kidneys we give an overview of the different types of cystic changes taking genetic aspects into account. Usually pathoanatomic types do not represent genetic entities: All type I kidneys are transmitted in an autosomal recessive way with varying clinical symptoms; in rare cases they even present in adults. The relationship to "congenital hepatic fibrosis", "cystic liver", and to the "Caroli syndrome" is discussed. Type II kidneys are usually not genetic in origin; but they may occur as part of several syndromes. Rarely genetic factors might contribute to type II kidneys that may present as familial cases of Potter syndrome ("renal non-function syndrome"). Type IV kidneys, although different in their pathoanatomic picture can be regarded according to a common pathogenetic theory as part of the spectrum of malformations as in type II. Therefore the genetic interpretation of type II kidneys also applies to type IV lesions. Type III kidneys include autosomal dominant polycystic kidney disease. This type may already present in childhood; the first prenatal diagnosis by ultrasonography is described in detail. Furthermore type III changes are part of syndromes or non-hereditary malformation complexes, and often present only as mild manifestations. Diseases with isolated involvement of the medulla (juvenile nephronophthisis/medullary cystic disease) or cortex are described as part of the differential diagnosis, they are heterogeneous and genetically only partly understood. Syndromes with cystic kidneys are reviewed as well as the possibilities of prenatal diagnosis of cystic diseases. Reliable prenatal diagnosis is only possible in type II, and possible in some of the other types. The nosology is improved if genetic information is taken into account.

Urologic manifestations of Laurence-Moon-Biedl syndrome

Although uremia is the major cause of death in more than 30 per cent of patients with Laurence-Moon-Biedl syndrome, little attention has been paid to this rare syndrome in the urologic literature. We herein report on 3 patients with this syndrome.

Ocular and systemic manifestations of the Bardet-Biedl syndrome

Four women with the Bardet-Biedl syndrome had ophthalmoscopic findings compatible with a severe rod-cone degeneration. The patients were legally blind (visual acuity, 20/200 or worse) in one or both eyes before the age of 30 years. Two patients with early involvement had macular bull's-eye pigment epithelial changes. Two other patients had more advanced disease with geographic atrophy of the macular pigment epithelium and underlying choriocapillaris. Bone spicule formation was variable. Electrophysiologic findings were consistent with severe derangement of both the rod and cone systems. All four patients had intraretinal capillary leakage along the vascular arcades and from the optic nerve without cystoid macular edema. Extensive endocrinologic evaluation showed no objective evidence of hypogenitalism in the three patients tested. Three patients had renal disease, secondary to vesicoureteral reflux, or hypertension, or both.

Dysplasia of the kidneys, liver, and pancreas: report of a variant of Ivemark's syndrome

A newborn girl with respiratory distress due to bilateral pneumothorax was found to be anuric, and died at 18 hours of age. Autopsy revealed a large pancreatic cyst, multiple large hepatic cysts, congenital hepatic fibrosis, bilateral dysplastic kidneys, and dysplasia of the pancreas. These findings constitute a variant of Ivemark's syndrome of dysplasia of the pancreas, liver, and kidneys.