A Case of Lateral Meningocele Syndrome without Lateral Meningoceles.

Introduction: Lateral meningocele syndrome (LMS), also known as Lehman syndrome, is caused by pathogenic variants in exon 33 of NOTCH3. Variants in this final exon of NOTCH3 interrupt the regulatory PEST domain, leading to enhanced NOTCH3 signaling due to prolonged cellular half-life. Individuals with LMS are expected to have multiple lateral meningoceles, developmental delay, neonatal hypotonia, dysmorphic facial features, and feeding difficulties. Case Presentation: We report an 8-year-old male with a history of autism, feeding difficulties, developmental delay, severe intellectual disability, and self-injurious behavior. Genetic testing revealed a NOTCH3 c.6663C>G (p.Y2221*) pathogenic variant in exon 33, consistent with a diagnosis of LMS. A follow-up spine MRI showed a ventral sacral extradural arachnoid cyst but no lateral meningoceles. This individual's most recent exam noted multiple dysmorphic features including prominent metopic ridging, broad forehead, downslanting palpebral fissures, high-arched palate, long narrow philtrum, mild pectus excavatum, and wide-based gait. Discussion/Conclusion: This individual shares the dysmorphic facial features, ongoing G-tube dependence, failure to thrive, and developmental delay seen in other individuals with LMS. His lack of lateral meningoceles expands the phenotype for this condition, as all previously reported individuals with molecularly confirmed LMS had multiple lateral meningoceles before age 8 years with an average age of identification at 4 years.

Phenotypic variability in Joubert syndrome is partially explained by ciliary pathophysiology.

INTRODUCTION: Joubert syndrome (JS) arises from defects of primary cilia resulting in potential malformations of the brain, kidneys, eyes, liver, and limbs. Several of the 35+ genes associated with JS have recognized genotype/phenotype correlations, but most genes have not had enough reported individuals to draw meaningful conclusions. METHODS: A PubMed literature review identified 688 individuals with JS across 32 genes and 112 publications to bolster known genotype/phenotype relationships and identify new correlations. All included patients had the "molar tooth sign" and a confirmed genetic diagnosis. Individuals were categorized by age, ethnicity, sex and the presence of developmental disability/intellectual disability, hypotonia, abnormal eye movements, ataxia, visual impairment, renal impairment, polydactyly, and liver abnormalities. RESULTS: Most genes demonstrated unique phenotypic profiles. Grouping proteins based on physiologic interactions established stronger phenotypic relationships that reflect known ciliary pathophysiology. Age-stratified data demonstrated that end-organ disease is progressive in JS. Most genes demonstrated a significant skew towards having variants with either residual protein function or no residual protein function. CONCLUSION: This cohort demonstrates that clinically meaningful genotype/phenotype relationships exist within most JS-related genes and can be referenced to allow for more personalized clinical care.