Molar tooth sign of the midbrain-hindbrain junction: occurrence in multiple distinct syndromes

Variable Clinical Presentations and Renal Outcome in Neonates With Autosomal Recessive Polycystic Kidney Disease

Autosomal recessive polycystic kidney disease (ARPKD) is caused by a mutation in the polycystic kidney and hepatic disease-1 (PKHD1) gene and is an important inherited cause of chronic kidney disease in children. The most typical presentations in neonates are massively enlarged kidneys with variable echogenicity, multiple small cysts, and congenital hepatic fibrosis. Potter sequence with pulmonary hypoplasia can present due to oligohydramnios. Severe pulmonary hypoplasia can lead to respiratory insufficiency and perinatal death. Some affected children can develop end-stage renal disease in early childhood or adolescence. Here, we report the clinical presentations, management, and renal outcomes of three neonatal cases of ARPKD from our center.

Rehabilitation Approach for Children With Joubert Syndrome and Related Disorders

Joubert syndrome and related disorders (JSRD) are rare and intractable diseases characterized by delayed psychomotor development, hypotonia and/or ataxia, and abnormal respiratory and eye movements. Cerebellar vermis agenesis and molar tooth signs are distinct on cerebral magnetic resonance imaging (MRI). Children with JSRD present with delayed psychomotor development, including intellectual disability and emotional or behavioral problems. Rehabilitation treatments are provided to promote psychomotor development. However, limited reports and evidence exist on rehabilitation treatments for children with JSRD. Three children with JSRD received rehabilitation treatment. The children received rehabilitation treatment once a week to once every one to two months at our hospital and/or other facilities. All patients received physical, occupational, and speech-language-hearing therapy, depending on their symptoms and conditions. In children with tracheostomies due to abnormal respiration, respiratory physical therapy and speech-language-hearing therapy, including augmentative and alternative communication, were needed. For hypotonia and ataxia, an orthotic intervention was considered in all three cases, and foot or ankle-foot orthoses were used in two cases. Although there is no specific or established rehabilitation method for children with JSRD, appropriate rehabilitation approaches, including physical, occupational, speech-language-hearing therapies and orthotic intervention, should be considered and provided to improve their function and expand their activity and participation. Orthotic intervention for hypotonia seems reasonable for improving gross motor development and function in children with JSRD.

Epilepsy in Joubert Syndrome: A Still Few Explored Matter

Epilepsy is rarely associated with Joubert's syndrome and related disorders (JSRD), being reported only in 3% of cases. Few patients have been described, moreover, with poor evidences of specific seizures' semiology or standard of practice for pharmacological treatment. Epilepsy is likely to be related to brain malformations in ciliopathies. Beyond the typical hindbrain malformation, the molar tooth sign, other cerebral anomalies variably reported in JSRD, such as generalized polymicrogyria, hamartomas, periventricular nodular heterotopia, and hippocampal defects, have been described. Herein, we aimed to revise the main clinical and etiopathogenetic characteristics of epilepsy associated with JSRD.

Joubert Syndrome with Oral-Facial-Digital Defect (JS-OFD): A Brief Overview on Clinics and Genetics

Joubert's syndrome with digital facial oral defects represents a rare subgroup of Joubert's syndrome with related disorders. There are 11 forms of oral-facial-digital syndromes and are characterized by having neurological signs of JS associated with orofacial anomalies and often polydactyly. The most severe variant is the OFD type VI (Varadi-Papp syndrome) in which there are tongue hamartomas, multiple frenula, midline notch of the upper lip, mesoaxial polydactyly, and hypothalamic hamartomas. Treatments are symptomatic and supportive with reconstructive surgery for correctable malformation and physical therapy, occupational therapy, speech therapy, and infant stimulation for mental delay.

The Role of Primary Cilia-Associated Phosphoinositide Signaling in Development

Primary cilia are microtube-based organelles that extend from the cell surface and function as biochemical and mechanical extracellular signal sensors. Primary cilia coordinate a series of signaling pathways during development. Cilia dysfunction leads to a pleiotropic group of developmental disorders, termed ciliopathy. Phosphoinositides (PIs), a group of signaling phospholipids, play a crucial role in development and tissue homeostasis by regulating membrane trafficking, cytoskeleton reorganization, and organelle identity. Accumulating evidence implicates the involvement of PI species in ciliary defects and ciliopathies. The abundance and localization of PIs in the cell are tightly regulated by the opposing actions of kinases and phosphatases, some of which are recently discovered in the context of primary cilia. Here, we review several cilium-associated PI kinases and phosphatases, including their localization along cilia, function in regulating the ciliary biology under normal conditions, as well as the connection of their disease-associated mutations with ciliopathies.

Meckel Gruber and Joubert Syndrome Diagnosed Prenatally: Allelism between the Two Ciliopathies, Complexities of Mutation Types and Digenic Inheritance

Background: Antenatally detected occipital encephalocele and polycystic kidneys are a common presentation of ciliopathies like Joubert syndrome and Meckel Gruber syndrome which have considerable genetic and phenotypic overlap. Case reports: We describe 3 cases of antenatally diagnosed occipital encephalocele and enlarged kidneys with fetal autopsy, histopathology & exome sequencing results. A novel nonsense variant in the CEP290 gene was reported in first case (Meckel syndrome). The second case shows the importance of fetal exome where the parents were carriers for 2 ciliopathy genes (TMEM138 & SDCCAG8). Diagnosis in this case was confirmed by fetal exome sequencing (Joubert syndrome). Multiexon deletion in TMEM67 and KIF14 present in trans was identified in the third case (Meckel syndrome), likely resulting in digenic inheritance. Conclusion: We report 2 cases of Meckel syndrome with a novel variant and multiexon deletion, and 1 case of Joubert syndrome which depicts the limitations of preconceptional carrier screening in ciliopathies due to overlapping phenotypes.

Joubert Syndrome and Renal Implication

Twenty-five to 30% of patients with Joubert syndrome (JS) have renal involvement. Two forms of renal disease (RD) have traditionally been described. The less common form is the Dekaban–Arima syndrome, a JS RD that includes congenital blindness and occasional encephalocele. The other, more common RD is juvenile nephronophthisis (NPHP), that presents a progressive interstitial fibrosis, associated with small cysts at the corticomedullary junction. NPHP is the most frequent genetic cause for end-stage RD in the first three decades of life. Symptoms start at approximately 6 years of age with urine concentrating defects, polydipsia, polyuria, and secondary enuresis.

Two Siblings Showing a Mild Phenotype of Joubert Syndrome with a Specific CEP290 Variant

Joubert syndrome (JS) is a genetic neurodevelopmental disorder characterized by lower brainstem dysplasia and cerebellar vermis agenesis termed molar tooth sign (MTS), psychomotor retardation, abnormal respiratory pattern in infancy, and oculomotor abnormalities. Arima syndrome (AS), which is a severe form of JS, is characterized by severe psychomotor retardation, congenital visual impairment, progressive renal dysfunction, and lower brainstem dysplasia from early infancy. Numerous patients with AS expire in early childhood. Recently, c.6012-12T> A in the CEP290 gene was reported as a specific variant of AS. Herein, we report the cases of two siblings showing a phenotype of JS with compound heterozygous mutations (c.6012-12T > A / c.5924delT) in the CEP290 gene. The older sister (aged 19 years) had hypotonia, hypertelorism, and anteverted nares since birth. As a neonate, she developed a transient abnormal respiratory pattern and nystagmus, and brain magnetic resonance imaging (MRI) showed MTS. The younger sister (aged 13 years) exhibited mild hypotonia and pendular nystagmus as a neonate; MRI revealed MTS. Both sisters had psychomotor retardation, oculomotor dysfunction, and bilateral renal cysts with normal renal function. They can walk and have simple conversation. They do not meet the diagnostic criteria for AS, and their symptoms were milder than those of previously reported cases with this specific mutation. This report indicates the expanding spectrum of the CEP290 variant.

Genotype-phenotype correlates in Joubert syndrome: A review

Joubert syndrome (JS) is a genetically heterogeneous primary ciliopathy characterized by a pathognomonic cerebellar and brainstem malformation, the “molar tooth sign,” and variable organ involvement. Over 40 causative genes have been identified to date, explaining up to 94% of cases. To date, gene‐phenotype correlates have been delineated only for a handful of genes, directly translating into improved counseling and clinical care. For instance, JS individuals harboring pathogenic variants in TMEM67 have a significantly higher risk of liver fibrosis, while pathogenic variants in NPHP1, RPGRIP1L, and TMEM237 are frequently associated to JS with renal involvement, requiring a closer monitoring of liver parameters, or renal functioning. On the other hand, individuals with causal variants in the CEP290 or AHI1 need a closer surveillance for retinal dystrophy and, in case of CEP290, also for chronic kidney disease. These examples highlight how an accurate description of the range of clinical symptoms associated with defects in each causative gene, including the rare ones, would better address prognosis and help guiding a personalized management. This review proposes to address this issue by assessing the available literature, to confirm known, as well as to propose rare gene‐phenotype correlates in JS.

SENIOR-LØKEN SYNDROME: A Case Series and Review of the Renoretinal Phenotype and Advances of Molecular Diagnosis

PURPOSE

To report genetic and clinical findings in a case series of 10 patients from eight unrelated families diagnosed with Senior-Løken syndrome.

METHODS

A retrospective study of patients with Senior-Løken syndrome. Data collected included clinical findings electroretinography and ocular imaging. Genetic analysis was based on molecular inversion probes, whole-exome sequencing (WES), and Sanger sequencing.

RESULTS

All patients who underwent electrophysiology (8/10) had widespread photoreceptor degeneration. Genetic analysis revealed two mutations in NPHP1, two mutations in NPHP4, and two mutations in IQCB1 (NPHP5). Five of the six mutations identified in the current study were found in a single family each in our cohort. The IQCB1-p.R461* mutation has been identified in 3 families. Patients harboring mutations in IQCB1 were diagnosed with Leber congenital amaurosis, while patients with NPHP4 and NPHP1 mutations showed early and sector retinitis pigmentosa, respectively. Full-field electroretinography was extinct for 6 of 10 patients, moderately decreased for two, and unavailable for another 2 subjects. Renal involvement was evident in 7/10 patients at the time of diagnosis. Kidney function was normal (based on serum creatinine) in patients younger than 10 years. Mutations in IQCB1 were associated with high hypermetropia, whereas mutations in NPHP4 were associated with high myopia.

CONCLUSION

Patients presenting with infantile inherited retinal degeneration are not universally screened for renal dysfunction. Modern genetic tests can provide molecular diagnosis at an early age and therefore facilitate early diagnosis of renal disease with recommended periodic screening beyond childhood and family planning.

Neonatal encephalopathy: Etiologies other than hypoxic-ischemic encephalopathy

Neonatal encephalopathy (NE) describes the clinical syndrome of a newborn with abnormal brain function that may result from a variety of etiologies. HIE should be distinguished from neonatal encephalopathy due to other causes using data gathered from the history, physical and neurological exam, and further investigations. Identifying the underlying cause of encephalopathy has important treatment implications. This review outlines conditions that cause NE and may be mistaken for HIE, along with their distinguishing clinical features, pathophysiology, investigations, and treatments. NE due to brain malformations, vascular causes, neuromuscular causes, genetic conditions, neurogenetic disorders and inborn errors of metabolism, central nervous system (CNS) and systemic infections, and toxic/metabolic disturbances are discussed.

KIAA0753-related skeletal ciliopathy: a ninth case, extending the phenotype and reporting a novel variant

KIAA0753-related skeletal ciliopathy is a recently described recessive disorder causing skeletal dysplasia and overlapping features of certain ciliopathies; Joubert, Jeune and Oro-facial-digital syndromes. We describe a ninth case that expands the phenotype; a 10-year-old girl with rhizomelic short stature (-5.6 SD), macrocephaly, developmental delay, CNS anomalies (thin corpus callosum, bilateral ventriculomegaly), cone-rod dystrophy, nystagmus, mild conductive hearing loss and recurrent chest infections secondary to confirmed ciliary dyskinesia. Testing for FGFR3 achondroplasia-related hotspots and mucopolysaccharidosis were negative. Whole-exome sequencing, aged eight, via skeletal dysplasia panel analysis and subsequent whole-genome sequencing (via the 100,000 genomes project) found no cause. WGS data reanalysis using exomiser uncovered compound heterozygous pathogenic KIAA0753 variants (frameshift and splice site). Further clinical and radiological surveys were consistent with the expected phenotype. We discuss the emerging phenotype of this uncommon disorder. This report details the sixth published case of skeletal dysplasia in all cases of KIAA0753-related disease and the first case to describe a novel c.1830-2A>G splice variant. Our case is the eldest woman reported to date (aged ten years) and the only known case to report associated hearing loss, leg-length discrepancy, pectus carinatum, respiratory ciliary dyskinesia and late-onset (9 years old) neuro-degenerative regression.

Visual Illusions in Radiology: Untrue Perceptions in Medical Images and Their Implications for Diagnostic Accuracy

Errors in radiologic interpretation are largely the result of failures of perception. This remains true despite the increasing use of computer-aided detection and diagnosis. We surveyed the literature on visual illusions during the viewing of radiologic images. Misperception of anatomical structures is a potential cause of error that can lead to patient harm if disease is seen when none is present. However, visual illusions can also help enhance the ability of radiologists to detect and characterize abnormalities. Indeed, radiologists have learned to exploit certain perceptual biases in diagnostic findings and as training tools. We propose that further detailed study of radiologic illusions would help clarify the mechanisms underlying radiologic performance and provide additional heuristics to improve radiologist training and reduce medical error.

Visual Neuropsychology in Development: Anatomo-Functional Brain Mechanisms of Action/Perception Binding in Health and Disease

Vision is the main entrance for environmental input to the human brain. Even if vision is our most used sensory modality, its importance is not limited to environmental exploration. Rather it has strong links to motor competences, further extending to cognitive and social aspects of human life. These multifaceted relationships are particularly important in developmental age and become dramatically evident in presence of complex deficits originating from visual aberrancies. The present review summarizes the available neuropsychological evidence on the development of visual competences, with a particular focus on the associated visuo-motor integration skills in health and disease. With the aim of supporting future research and interventional settings, the goal of the present review is to constitute a solid base to help the translation of neuropsychological hypotheses into straightforward empirical investigations and rehabilitation/training protocols. This approach will further increase the impact, ameliorate the acceptance, and ease the use and implementation of lab-derived intervention protocols in real-life situations.

Treatment of dental caries in a patient with Joubert syndrome without the use of sedatives: A case study

BACKGROUND

Joubert syndrome (JS) is a rare autosomal recessive inherited ciliopathy caused by gene mutation. Manifestations can include intermittent dyspnea, apnea, ataxia, and other nervous system abnormalities.

CASE PRESENTATION

The patient was a 21-year-old female with JS, severe intellectual disability, cerebral palsy, and epilepsy. Dental caries in both mandibular lower first molars was diagnosed by a local dentist, and the patient was referred to us for further treatment. Although her oral hygiene was good, the dental caries had reached the vicinity of the dental pulp. The caries had developed symmetrically on both first molars and was completely covered with the gingiva. As she was hesitant to receive treatment without anxiolysis, we considered using general anesthesia or intravenous sedation. However, we were recommended against it by the patient's family doctor because of the risk of apneic episodes in JS. Accordingly, dental treatment was performed over multiple days through physical behavior adjustment, while providing oxygenation (3 L/min) in preparation for an apneic episode. The dental treatment was successfully completed with a good postoperative outcome.

CONCLUSIONS

Dental treatment can be safely performed in patients with JS through physical behavior adjustment, thereby minimizing the risk of an apnea attack.

WD40-Repeat Proteins in Ciliopathies and Congenital Disorders of Endocrine System

WD40-repeat (WDR)-containing proteins constitute an evolutionarily conserved large protein family with a broad range of biological functions. In human proteome, WDR makes up one of the most abundant protein-protein interaction domains. Members of the WDR protein family play important roles in nearly all major cellular signalling pathways. Mutations of WDR proteins have been associated with various human pathologies including neurological disorders, cancer, obesity, ciliopathies and endocrine disorders. This review provides an updated overview of the biological functions of WDR proteins and their mutations found in congenital disorders. We also highlight the significant role of WDR proteins in ciliopathies and endocrine disorders. The new insights may help develop therapeutic approaches targeting WDR motifs.

Total Intravenous Anesthesia in Joubert Syndrome Patient for Otorhinolaryngology Surgery: A Case Report and Mini Review of the Literature

BACKGROUND Joubert syndrome is a rare autosomal recessive disorder first described in 1969, with an estimated prevalence of 1 in 100 000. Joubert syndrome is characterized by partial or complete agenesis of the cerebellar vermis - the structure that connects both parts of the cerebellum. This results in the main clinical symptoms, such as muscular hypotonia, ataxia, mental retardation, abnormal eye movements, and a central apnea breathing pattern. Joubert syndrome can combine neurological signs with variable multi-organ involvement, mainly of the retina, kidneys, liver, and musculoskeletal system. CASE REPORT A 13-year-old boy presenting with recurrent otitis media, fever, respiratory infections, and tonsillar hyperplasia needed surgery. At the otorhinolaryngology outpatient clinic, the indication for surgical paracentesis, adenoidectomy, and tonsillectomy under general anesthesia (first in his life) was set. We performed a total intravenous anesthesia (TIVA) using propofol (described as safe) and remifentanil (organ-independent metabolism) without any side-effects. For postoperative pain therapy we used metamizole instead of paracetamol in order to avoid liver injury. CONCLUSIONS Due to the possible facial dysmorphism we recommend a critical evaluation of the airway to assess a potential difficult airway preoperatively. Our case underlines that TIVA, with the medications used in this case, is safe. We refrained from premedication in order not to trigger central apnea. For safety reasons, all preparatory procedures were carried out in the recovery room under monitor surveillance and with audio-visual distraction for the patient in order to reduce the stress level. For postoperative pain therapy, we recommend the use of metamizole.

Indian child with novel variant in OFD1 gene

Orofaciodigital syndrome (OFD) can have variable phenotype and presents with oral anomalies, facial dysmorphism, and digital malformations like syndactyly, and polydactyly. Other presentations also include renal and cardiac defects, and central nervous system anomalies like hydrocephalus and cerebellar abnormalities. OFD1 is a X-linked dominant form of the syndrome presenting in females with mutations in CXorf5 or OFD1 gene. We describe a young child with sparse hairs, milia over face and absence of corpus callosum. Next generation sequencing showed frameshift pathogenic variant in the exon 13 of the OFD1 gene, consistent with diagnosis of OFD1.

Novel biallelic loss-of-function variants in CEP290 cause Joubert syndrome in two siblings

Background

Joubert syndrome (JS) is a rare genetic disorder, which can be defined by brain stem malformation, cerebellar vermis hypoplasia, and consequent “molar tooth sign” (MTS). JS always shares variety of phenotypes in development defects. With the development of next-generation sequencing, dozens of causative genes have been identified to JS so far. Here, we investigated two male siblings with JS and uncovered a novel pathogenesis through combined methods.

Results

The siblings shared similar features of nystagmus, disorders of intellectual development, typical MTS, and abnormal morphology in fourth ventricle. Whole-exome sequencing (WES) and chromosome comparative genomic hybridization (CGH) were then performed on the proband. Strikingly, a maternal inherited nonsense variant (NM_025114.3: c.5953G>T [p.E1985*]) in CEP290 gene and a paternal inherited deletion in 12q21.32 including exons 1 to 10 of CEP290 gene were identified in the two affected siblings. We further confirmed the two variants by in vitro experiments: quantitative PCR and PCR sequencing.

Conclusions

In this study, we first reported a novel causative mechanism of Joubert syndrome: a copy number variation (CNV) combined with a single-nucleotide variant in CEP290 gene, which can be helpful in the genetic diagnosis of this disease.

Ahi1 promotes Arl13b ciliary recruitment, regulates Arl13b stability and is required for normal cell migration

Mutations in the Abelson-helper integration site 1 (AHI1) gene are associated with neurological/neuropsychiatric disorders, and cause the neurodevelopmental ciliopathy Joubert syndrome (JBTS). Here, we show that deletion of the transition zone (TZ) protein Ahi1 in mouse embryonic fibroblasts (MEFs) has a small effect on cilia formation. However, Ahi1 loss in these cells results in: (1) reduced localization of the JBTS-associated protein Arl13b to the ciliary membrane, (2) decreased sonic hedgehog signaling, (3) and an abnormally elongated ciliary axoneme accompanied by an increase in ciliary IFT88 concentrations. While no changes in Arl13b levels are detected in crude cell membrane extracts, loss of Ahi1 significantly reduced the level of non-membrane-associated Arl13b and its stability via the proteasome pathway. Exogenous expression of Ahi1-GFP in Ahi1^-/- MEFs restored ciliary length, increased ciliary recruitment of Arl13b and augmented Arl13b stability. Finally, Ahi1^-/- MEFs displayed defects in cell motility and Pdgfr-α-dependent migration. Overall, our findings support molecular mechanisms underlying JBTS etiology that involve: (1) disruptions at the TZ resulting in defects of membrane- and non-membrane-associated proteins to localize to primary cilia, and (2) defective cell migration.This article has an associated First Person interview with the first author of the paper.

The molecular genetics of Joubert syndrome and related ciliopathies: The challenges of genetic and phenotypic heterogeneity

Joubert syndrome (JS; MIM PS213300) is a rare, typically autosomal recessive disorder characterized by cerebellar vermis hypoplasia and a distinctive malformation of the cerebellum and brainstem identified as the “molar tooth sign” on brain MRI. Other universal features include hypotonia with later ataxia and intellectual disability/developmental delay, with additional features consisting of oculomotor apraxia and abnormal respiratory pattern. Notably, other, more variable features include renal cystic disease, typically nephronophthisis, retinal dystrophy, and congenital hepatic fibrosis; skeletal changes such as polydactyly and findings consistent with short-rib skeletal dysplasias are also seen in many subjects. These pleiotropic features are typical of a number of disorders of the primary cilium, and make the identification of causal genes challenging given the significant overlap between JS and other ciliopathy conditions such as nephronophthisis and Meckel, Bardet-Biedl, and COACH syndromes. This review will describe the features of JS, characterize the 35 known genes associated with the condition, and describe some of the genetic conundrums of JS, such as the heterogeneity of founder effects, lack of genotype-phenotype correlations, and role of genetic modifiers. Finally, aspects of JS and related ciliopathies that may pave the way for development of therapeutic interventions, including gene therapy, will be described.

Diffusion Tensor Imaging of Brain Malformations: Exploring the Internal Architecture

Diffusion tensor imaging (DTI) is an advanced MR imaging technique that provides noninvasive qualitative and quantitative information about the white matter microarchitecture. By measuring the three-dimensional directional characteristics of water molecule diffusion/mobility, DTI generates unique tissue contrasts that are used to study the axonal organization of the central nervous system. Its applications include quantitative evaluation of the brain connectivity, development, and white matter diseases. This article reviews DTI and fiber tractography findings in several brain malformations and highlights the added value of DTI and fiber tractography compared with conventional MR imaging.

Prenatal diagnosis of brainstem anomalies

Prenatal diagnosis of brainstem anomalies is important due to the usually associated neurodevelopmental impairment and genetic implications. The extreme developmental changes that the brainstem and cerebellum undergo during fetal life pose a challenge for the characterization and definition of the different malformations. The present review aims to demonstrate the normal development of the fetal brainstem and to present the main features required for diagnosis of its anomalies according to available data in the medical literature.

Joubert Syndrome: Ophthalmological Findings in Correlation with Genotype and Hepatorenal Disease in 99 Patients Prospectively Evaluated at a Single Center

PURPOSE

Joubert syndrome (JS) is caused by mutations in >34 genes that encode proteins involved with primary (nonmotile) cilia and the cilium basal body. This study describes the varying ocular phenotypes in JS patients, with correlation to systemic findings and genotype.

DESIGN

Patients were systematically and prospectively examined at the National Institutes of Health (NIH) Clinical Center in the setting of a dedicated natural history clinical trial.

PARTICIPANTS

Ninety-nine patients with JS examined at a single center.

METHODS

All patients underwent genotyping for JS, followed by complete age-appropriate ophthalmic examinations at the NIH Clinical Center, including visual acuity (VA), fixation behavior, lid position, motility assessment, slit-lamp biomicroscopy, dilated fundus examination with an indirect ophthalmoscope, and retinoscopy. Color and fundus autofluorescence imaging, Optos wide-field photography (Dunfermline, Scotland, UK), and electroretinography (ERG) were performed when possible.

MAIN OUTCOME MEASURES

The VA (with longitudinal follow-up where possible), ptosis, extraocular muscle function, retinal and optic nerve status, and retinal function as measured by ERG.

RESULTS

Among patients with JS with quantifiable VA (68/99), values ranged from 0 logarithm of the minimum angle of resolution (logMAR) (Snellen 20/20) to 1.5 logMAR (Snellen 20/632). Strabismus (71/98), nystagmus (66/99), oculomotor apraxia (60/77), ptosis (30/98), coloboma (28/99), retinal degeneration (20/83), and optic nerve atrophy (8/86) were identified.

CONCLUSIONS

We recommend regular monitoring for ophthalmological manifestations of JS beginning soon after birth or diagnosis. We demonstrate delayed visual development and note that the amblyogenic time frame may last significantly longer in JS than is typical. In general, patients with coloboma were less likely to display retinal degeneration, and those with retinal degeneration did not have coloboma. Severe retinal degeneration that is early and aggressive is seen in disease caused by specific genes, such as CEP290- and AHI1-associated JS. Retinal degeneration in INPP5E-, MKS1-, and NPHP1-associated JS was generally milder. Finally, ptosis surgery can be helpful in a subset of patients with JS; decisions as to timing and benefit/risk ratio need to be made on an individual basis according to expert consultation.

Characteristics of Liver Disease in 100 Individuals With Joubert Syndrome Prospectively Evaluated at a Single Center

BACKGROUND AND AIMS

Joubert Syndrome (JS) is a rare, inherited, ciliopathy defined by cerebellar and brainstem malformations and is variably associated with liver, kidney, and ocular dysfunction. This study characterizes the hepatic findings in JS and identifies factors associated with probable portal hypertension.

METHODS

Hundred individuals with JS were prospectively evaluated at the National Institutes of Health Clinical Center. Laboratory tests, imaging, and DNA sequencing were performed. Patients were stratified based on the spleen length/patient height ratio as a marker of splenomegaly, used as a surrogate for probable portal hypertension.

RESULTS

Forty-three patients (43%) had liver involvement based on elevated liver enzymes and/or liver hyperechogenicity and/or splenomegaly. None of the patients had macroscopic liver cysts or bile duct dilatation. Based on the spleen length/patient height ratio, 13 patients were stratified into a probable portal hypertension group. We observed significant elevations in alkaline phosphatase (269 vs 169 U/L, P ≤ 0.001), alanine aminotransferase (92 vs 42 U/L, P = 0.004), aspartate aminotransferase (77 vs 40 U/L, P = 0.002), and gamma-glutamyl transferase (226 vs 51 U/L, P ≤ 0.001) in the probable portal hypertension group. Platelets were lower in the probable portal hypertension cohort (229 vs 299 × 10 cells/μL, P = 0.008), whereas synthetic function was intact in both groups. Probable portal hypertension was also more prevalent in patients with kidney disease (P = 0.001) and colobomas (P = 0.02), as well as mutations in the TMEM67 gene (P = 0.001).

CONCLUSIONS

In JS, probable portal hypertension is associated with abnormal hepatic enzymes, as well as presence of kidney disease, coloboma, and/or mutation in TMEM67. These findings may allow early identification of JS patients who have or are more likely to develop liver disease.

Renal cystic disease and associated ciliopathies

PURPOSE OF REVIEW

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

RECENT FINDINGS

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

SUMMARY

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

Fetal cerebellar disorders

The embryologic development of the cerebellum extends over a long time period, thus making it vulnerable to a broad spectrum of malformations and disruptions. Knowledge of the main steps of fetal posterior fossa development; the normal imaging patterns at different stages of embryogenesis; the large spectrum of cerebellar malformations; and their clinical presentations enables diagnosis and precise counseling of parents. Sonography is the most important imaging method for the screening of cerebellar malformations since it is noninvasive, widely available, and safe for both mother and child. The ultrasonographic approach for the evaluation of the fetal posterior fossa is based on the classic transabdominal visualization of axial planes with addition when indicated of a more comprehensive, multiplanar transvaginal or transfundal approach, including coronal and sagittal imaging planes. Fetal magnetic resonance imaging (MRI) has become an adjunct to prenatal ultrasound since the 1980s. Good-quality images have been obtained thanks to the implementation of fast and ultrafast MRI sequences. Fetal MRI has higher-contrast resolution than prenatal sonography and may contribute to the differentiation of normal from abnormal tissue. Both prenatal neurosonography and fetal MRI enable accurate prenatal diagnosis of most posterior fossa anomalies.

Prospective Evaluation of Kidney Disease in Joubert Syndrome

BACKGROUND AND OBJECTIVES

Joubert syndrome is a genetically heterogeneous ciliopathy associated with >30 genes. The characteristics of kidney disease and genotype-phenotype correlations have not been evaluated in a large cohort at a single center.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We evaluated 97 individuals with Joubert syndrome at the National Institutes of Health Clinical Center using abdominal ultrasonography, blood and urine chemistries, and DNA sequencing.

RESULTS

Patients were ages 0.6-36 years old (mean of 9.0±7.6 years old); 41 were female. Mutations were identified in 19 genes in 92 patients; two thirds of the mutations resided in six genes: TMEM67, C5orf42, CC2D2A, CEP290, AHI1, and KIAA0586. Kidney disease was detected in 30%, most commonly in association with the following genes: CEP290 (six of six), TMEM67 (11 of 22), and AHI1 (three of six). No kidney disease was identified in patients with mutations in C5orf42 (zero of 15) or KIAA0586 (zero of six). Prenatal ultrasonography of kidneys was normal in 72% of patients with kidney disease. Specific types of kidney disease included nephronophthisis (31%), an overlap phenotype of autosomal recessive polycystic kidney disease/nephronophthisis (35%), unilateral multicystic dysplastic kidney (10%), and indeterminate-type cystic kidney disease (24%). Early-onset hypertension occurred in 24% of patients with kidney disease. Age at ESRD (n=13) ranged from 6 to 24 years old (mean of 11.3±4.8 years old).

CONCLUSIONS

Kidney disease occurs in up to one third of patients with Joubert syndrome, most commonly in those with mutations in CEP290, TMEM67, and AHI1. Patients with mutations in C5orf42 or KIAA0586 are less likely to develop kidney disease. Prenatal ultrasonography is a poor predictor of kidney involvement in Joubert syndrome. Unilateral multicystic dysplastic kidney and autosomal recessive polycystic kidney disease-like enlarged kidneys with early-onset hypertension can be part of the Joubert syndrome kidney phenotype.

A novel homozygous ARL13B variant in patients with Joubert syndrome impairs its guanine nucleotide-exchange factor activity

ARL13B encodes for the ADP-ribosylation factor-like 13B GTPase, which is required for normal cilia structure and Sonic hedgehog (Shh) signaling. Disruptions in cilia structure or function lead to a class of human disorders called ciliopathies. Joubert syndrome is characterized by a wide spectrum of symptoms, including a variable degree of intellectual disability, ataxia, and ocular abnormalities. Here we report a novel homozygous missense variant c.[223G>A] (p.(Gly75Arg) in the ARL13B gene, which was identified by whole-exome sequencing of a trio from a consanguineous family with multiple-affected individuals suffering from intellectual disability, ataxia, ocular defects, and epilepsy. The same variant was also identified in a second family. We saw a striking difference in the severity of ataxia between affected male and female individuals in both families. Both ARL13B and ARL13B-c.[223G>A] (p.(Gly75Arg) expression rescued the cilia length and Shh defects displayed by Arl13b hennin (null) cells, indicating that the variant did not disrupt either ARL13B function. In contrast, ARL13B-c.[223G>A] (p.(Gly75Arg) displayed a marked loss of ARL3 guanine nucleotide-exchange factor activity, with retention of its GTPase activities, highlighting the correlation between its loss of function as an ARL3 guanine nucleotide-exchange factor and Joubert syndrome.

Physiotherapy and Rehabilitation in a Child with Joubert Syndrome

Objective

Joubert syndrome (JS) is a rare autosomal recessive genetic disorder characterized by brain malformation, hypotonia, breathing abnormalities, ataxia, oculomotor apraxia, and developmental delay. The purpose of this study was to report the efficiency of the physiotherapy and rehabilitation program in a child with JS.

Materials and Methods

Our case is a 19-month-old female child with mild clinical signs of JS. The pretreatment and posttreatment motor functioning level of the case was evaluated through the Gross Motor Function Measure (GMFM), whereas the independence level was evaluated through the Pediatric Functional Independence Measure (WeeFIM). The case was included in the rehabilitation program by the physiotherapist for one hour for five days a week throughout the period of 13 months in accordance with the neurodevelopmental treatment principles.

Results

The case was able to turn around from the supine position to the reverse direction by oneself, and she was able to rise on her forearms facedown and was able to sit, crawl, and walk independently. The GMFM score was 210, whereas WeeFIM score was 65.

Discussion

In the direction of those findings, in Joubert Syndrome, physiotherapy and rehabilitation can be effective in coping with the symptoms causing developmental delay.

Lingual Frenectomy in Joubert Syndrome

AIM

Our aim is to present a case of a rare disorder, such as Joubert syndrome (JS) which required oral surgical intervention under general anesthesia at a very young age to help in achieving normal developmental milestones.

BACKGROUND

Ciliopathies are an emerging class of diseases of which JS is a significant member. There have been very few cases of JS with its distinguishing features which have been reported in recent literature.

CASE REPORT

We herewith present a case of JS who reported to our unit with a complaint of speech abnormality. Intraoral examination revealed a tongue-tie which was planned for surgical release. As any drugs that interfere with respiratory depression have to be used with utmost care, adequate precautions were taken in this case and the patient was treated under general anesthesia. The tongue-tie was released and associated ham-artomatous outgrowths from the floor of the mouth were also excised. Appropriate postoperative care was taken and the patient was discharged.

CONCLUSION

The patient treated by us did not reveal any significant intraoperative or postoperative complications. Treatment of cases of JS required a team effort of multiple dental and medical specialists. Long-term follow-up of such patients is required so that they achieve normal chronological development.

CLINICAL SIGNIFICANCE

Joubert syndrome being a rare disorder requires special anesthetic care during any surgical procedure, especially that involving the oral cavity. The need and timing of surgical intervention in such cases should be carefully assessed and appropriate precautions should be taken.

Neuropsychological phenotypes of 76 individuals with Joubert syndrome evaluated at a single center

Joubert syndrome (JS) is a genetically heterogeneous ciliopathy characterized by hypo-dysplasia of the cerebellar vermis, a distinct hindbrain/midbrain malformation (molar tooth sign), and intellectual disability. We evaluated the neuropsychological profiles of 76 participants with JS in the context of molecular genetics and clinical covariates. Evaluations included neuropsychological testing, structured parental interviews, DNA sequencing, brain magnetic resonance imaging (MRI), electroencephalography (EEG), ophthalmologic examination, and assessment for renal and hepatic disease. On average, participants manifested Full Scale Intelligence Quotients (FSIQ) in the moderately to profoundly low range (M = 64.3 ± 15.3). Of the Wechsler index scores, verbal comprehension was least affected and processing speed was most affected. Receptive language was rated as better than expressive language on the Vineland Adaptive Behavior Scales-Second Edition. Those with abnormal EEG had a significantly lower FSIQ (n = 15; M = 50.7 ± 12.9) compared to participants with normal EEG (n = 39; M = 64.7 ± 16.3; p = .004). Participants taking psychiatric medications manifested a lower FSIQ (n = 20; M = 54.8 ± 13.2) than those not taking them (n = 42; M = 65.0 ± 17.2; p = .022). These correlations were also present in the TMEM67-related JS sub-cohort (n = 14). Based on parental assessment, psychiatric and behavioral problems were significantly more common than in the general population for all measures (p < .004 for all). The majority (65%) of individuals with JS have some degree of intellectual disability. Abnormal EEG is associated with lower neuropsychological function. Processing speed is a weakness, while verbal comprehension and receptive language are relative strengths. These findings may guide parents, teachers, therapists, and doctors to determine appropriate therapies, accommodations, and academic goals for individuals with JS.

Molecular genetic findings and clinical correlations in 100 patients with Joubert syndrome and related disorders prospectively evaluated at a single center

PURPOSE

Joubert syndrome (JS) is a genetically and clinically heterogeneous ciliopathy characterized by distinct cerebellar and brainstem malformations resulting in the diagnostic "molar tooth sign" on brain imaging. To date, more than 30 JS genes have been identified, but these do not account for all patients.

METHODS

In our cohort of 100 patients with JS from 86 families, we prospectively performed extensive clinical evaluation and provided molecular diagnosis using a targeted 27-gene Molecular Inversion Probes panel followed by whole-exome sequencing (WES).

RESULTS

We identified the causative gene in 94% of the families; 126 (27 novel) unique potentially pathogenic variants were found in 20 genes, including KIAA0753 and CELSR2, which had not previously been associated with JS. Genotype-phenotype correlation revealed the absence of retinal degeneration in patients with TMEM67, C5orf52, or KIAA0586 variants. Chorioretinal coloboma was associated with a decreased risk for retinal degeneration and increased risk for liver disease. TMEM67 was frequently associated with kidney disease.

CONCLUSION

In JS, WES significantly increases the yield for molecular diagnosis, which is essential for reproductive counseling and the option of preimplantation and prenatal diagnosis as well as medical management and prognostic counseling for the age-dependent and progressive organ-specific manifestations, including retinal, liver, and kidney disease.Genet Med advance online publication 26 January 2017.

Evidence for a "Pathogenic Triumvirate" in Congenital Hepatic Fibrosis in Autosomal Recessive Polycystic Kidney Disease

Autosomal recessive polycystic kidney disease (ARPKD) is a severe monogenic disorder that occurs due to mutations in the PKHD1 gene. Congenital hepatic fibrosis (CHF) associated with ARPKD is characterized by the presence of hepatic cysts derived from dilated bile ducts and a robust, pericystic fibrosis. Cyst growth, due to cyst wall epithelial cell hyperproliferation and fluid secretion, is thought to be the driving force behind disease progression. Liver fibrosis is a wound healing response in which collagen accumulates in the liver due to an imbalance between extracellular matrix synthesis and degradation. Whereas both hyperproliferation and pericystic fibrosis are hallmarks of CHF/ARPKD, whether or not these two processes influence one another remains unclear. Additionally, recent studies demonstrate that inflammation is a common feature of CHF/ARPKD. Therefore, we propose a "pathogenic triumvirate" consisting of hyperproliferation of cyst wall growth, pericystic fibrosis, and inflammation which drives CHF/ARPKD progression. This review will summarize what is known regarding the mechanisms of cyst growth, fibrosis, and inflammation in CHF/ARPKD. Further, we will discuss the potential advantage of identifying a core pathogenic feature in CHF/ARPKD to aid in the development of novel therapeutic approaches. If a core pathogenic feature does not exist, then developing multimodality therapeutic approaches to target each member of the "pathogenic triumvirate" individually may be a better strategy to manage this debilitating disease.

Neuroimaging Findings and Repeat Neuroimaging Value in Pediatric Chronic Ataxia

BACKGROUND

Chronic ataxia, greater than two months in duration, is encountered relatively commonly in clinical pediatric neurology practise and presents with diagnostic challenges. It is caused by multiple and diverse disorders. Our aims were to describe the neuroimaging features and the value of repeat neuroimaging in pediatric chronic ataxia to ascertain their contribution to the diagnosis and management.

MATERIALS AND METHODS

A retrospective charts and neuroimaging reports review was undertaken in 177 children with chronic ataxia. Neuroimaging in 130 of 177 patients was also reviewed.

RESULTS

Nineteen patients had head computed tomography only, 103 brain magnetic resonance imaging only, and 55 had both. Abnormalities in the cerebellum or other brain regions were associated with ataxia. Neuroimaging was helpful in 73 patients with 30 disorders: It was diagnostic in 9 disorders, narrowed down the diagnostic possibilities in 14 disorders, and revealed important but non-diagnostic abnormalities, e.g. cerebellar atrophy in 7 disorders. Having a normal magnetic resonance imaging scan was mostly seen in genetic diseases or in the early course of ataxia telangiectasia. Repeat neuroimaging, performed in 108 patients, was generally helpful in monitoring disease evolution and in making a diagnosis. Neuroimaging was not directly helpful in 36 patients with 10 disorders or by definition the 55 patients with unknown disease etiology.

CONCLUSIONS

Normal or abnormal neuroimaging findings and repeat neuroimaging are very valuable in the diagnosis and management of disorders associated with pediatric chronic ataxia.

Orofacial manifestations and dental considerations in association with Varadi-Papp syndrome: report of a rare case

Varadi-Papp syndrome or oral-facial-digital syndrome type VI (OFDS VI) is a rare, autosomal recessive disorder characterised by a specific congenital malformation of the cerebellum and a broad spectrum of other phenotypic findings. It is distinguished from other OFDSs by metacarpal abnormalities with central polydactyly and by cerebellar abnormalities. Treatment for such patients is often considered challenging due to the presence of intellectual disability, hypotonia, and abnormal respiratory pattern in these patients. The present article reports the oral and systemic manifestations of a 5-year-old female patient having Varadi-Papp syndrome, considerations taken in her dental treatment and the successful management performed. The patient was followed up every 3 months for 2 years, to evaluate plaque control and to continue with the plaque control regimen. Periodic oral examinations and maintenance of good oral hygiene helped to improve the quality of life of the child. This case illustrates the favourable treatment outcomes in a Varadi-Papp syndrome patient. Furthermore, the need for periodic oral examinations and maintenance of good oral hygiene to prevent any complications in such patients has been highlighted.

Genomic variants and variations in malformations of cortical development

Malformations of cortical development (MCDs) are a common cause of neurodevelopmental delay and epilepsy and are caused by disruptions in the normal development of the cerebral cortex. Several causative genes have been identified in patients with MCD. There is increasing evidence of role of de novo mutations, including those occurring post fertilization, in MCD. These somatic mutations may not be detectable by traditional methods of genetic testing performed on blood DNA. Identification of the genetic cause can help in guiding families in future pregnancies. Research has highlighted how elucidation of key molecular pathways can also allow for targeted therapeutic interventions.

Molar Tooth Sign with Deranged Liver Function Tests: An Indian Case with COACH Syndrome

We report the first genetically proven case of COACH syndrome from the Indian subcontinent in a 6-year-old girl who presented with typical features of Joubert syndrome along with hepatic involvement. Mutation analysis revealed compound heterozygous missense mutation in the known gene TMEM67 (also called MKS3).

Systemic diseases associated with retinal dystrophies

Inherited retinal degeneration (IRD) may occur in isolation or as part of a multi-systemic condition. Ocular manifestations may be the presenting symptom of a syndromic disease and can include retinitis pigmentosa, cone-rod dystrophy, or maculopathy. Alternatively, patients affected with syndromic disease may already have other systemic manifestations at the time retinal disease is diagnosed. Some of these systemic diseases can cause significant morbidity. Here, we review several of these syndromic IRDs and their underlying genetic causes. Early recognition and referral for systemic evaluation and surveillance may lead to early intervention and an improved outcome. Obtaining a molecular diagnosis can be beneficial in securing a definitive diagnosis, especially in cases with atypical presentations. A genetic diagnosis may also be informative with regard to prognosis and potential therapies. Effective management and rehabilitation for patients with syndromic retinal dystrophy requires a comprehensive genetic-based team approach involving patients, family members, ophthalmologists, primary care physicians, and geneticists.

Exome sequencing identifies a homozygous C5orf42 variant in a Turkish kindred with oral-facial-digital syndrome type VI

Oral-facial-digital syndrome type VI (OFDVI) is a rare ciliopathy in the spectrum of Joubert syndrome (JS) and distinguished from other oral-facial-digital syndromes by metacarpal abnormalities with central polydactyly and by a molar tooth sign on cranial MRI. Additional characteristic features include short stature, micrognathia, posteriorly rotated low-set ears, hypertelorism, epicanthal folds, broad nasal tip, tongue hamartoma, upper lip notch, intraoral frenula, cleft lip/palate, and renal anomalies. Recently, novel mutations in C5orf42 were identified in 9 out of 11 OFDVI families. In a subsequent study C5orf42 was found to be mutated in only 2 out of 17 OFDVI probands while 28 patients with a pure JS phenotype also had pathogenic mutations of C5orf42. We report on two affected cousins diagnosed with OFDVI who were born from first degree cousin marriages. Whole exome sequencing (WES) identified a homozygous predicted damaging missense mutation (c.4034A > G; p.Gln1345Arg) in the C5orf42 gene. Our data contribute to the evidence that C5orf42 is one of the causative genes for OFDVI.

Senior- loken syndrome - a ciliopathy

Senior - Loken syndrome is a rare combination of juvenile nephronophthisis and tapeto - retinal degeneration. The author describes two patients who presented with varying degrees of retinal dystrophy and renal insufficiency in their second decade of life. Both the patients presented with severe renal failure requiring hemodialysis. The first patient had early onset progressive retinal degeneration leading to childhood blindness whereas the second patient had asymptomatic retinitis pigmentosa. These cases are presented to highlight the spectrum of eye manifestations of Senior - Loken syndrome. This report also stresses the need for fundus evaluation in patients with chronic kidney disease presenting in second decade of life even if asymptomatic.