1. Semaphorin-Plexin Signaling: From Axonal Guidance to a New X-Linked Intellectual Disability Syndrome
- Author
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Kenneth A. Myers, Ebba Alkhunaizi, Michelle M. Morrow, Jiddeke J.P. van de Kamp, Elysa J. Marco, Suma P. Shankar, Harvey B. Sarnat, Marwan Shinawi, Jacqueline L. Steele, Megan Glassford, Colette P. DeFilippo, Tracy Brandt, Amy Waldman, Houda Zghal Elloumi, Holly Dubbs, Ganka Douglas, Sumit Parikh, Kristin G. Monaghan, Cyril Mignot, David Chitayat, Bénédicte Héron, Linda E. Kim, Farrah Rajabi, Shane C. Quinonez, William D. Graf, Mark C. Hannibal, Aravindhan Veerapandiyan, Human genetics, Amsterdam Neuroscience - Complex Trait Genetics, and Amsterdam Gastroenterology Endocrinology Metabolism
- Subjects
Adult ,Male ,Adolescent ,Autism Spectrum Disorder ,X-linked intellectual disability ,Genetic counseling ,Nerve Tissue Proteins ,Receptors, Cell Surface ,Semaphorins ,Young Adult ,Neurodevelopmental disorder ,Developmental Neuroscience ,Semaphorin ,Intellectual Disability ,Intellectual disability ,Humans ,Medicine ,Child ,Genetic Association Studies ,X chromosome ,Genetics ,biology ,business.industry ,Plexin ,medicine.disease ,Neurology ,Child, Preschool ,Pediatrics, Perinatology and Child Health ,biology.protein ,Autism ,Neurology (clinical) ,business ,Cell Adhesion Molecules ,Signal Transduction - Abstract
Background: Semaphorins and plexins are ligands and cell surface receptors that regulate multiple neurodevelopmental processes such as axonal growth and guidance. PLXNA3 is a plexin gene located on the X chromosome that encodes the most widely expressed plexin receptor in fetal brain, plexin-A3. Plexin-A3 knockout mice demonstrate its role in semaphorin signaling in vivo. The clinical manifestations of semaphorin/plexin neurodevelopmental disorders have been less widely explored. This study describes the neurological and neurodevelopmental phenotypes of boys with maternally inherited hemizygous PLXNA3 variants. Methods: Data-sharing through GeneDx and GeneMatcher allowed identification of individuals with autism or intellectual disabilities (autism/ID) and hemizygous PLXNA3 variants in collaboration with their physicians and genetic counselors, who completed questionnaires about their patients. In silico analyses predicted pathogenicity for each PLXNA3 variant. Results: We assessed 14 boys (mean age, 10.7 [range 2 to 25] years) with maternally inherited hemizygous PLXNA3 variants and autism/ID ranging from mild to severe. Other findings included fine motor dyspraxia (92%), attention-deficit/hyperactivity traits, and aggressive behaviors (63%). Six patients (43%) had seizures. Thirteen boys (93%) with PLXNA3 variants showed novel or very low allele frequencies and probable damaging/disease-causing pathogenicity in one or more predictors. We found a genotype-phenotype correlation between PLXNA3 cytoplasmic domain variants (exons 22 to 32) and more severe neurodevelopmental disorder phenotypes (P < 0.05). Conclusions: We report 14 boys with maternally inherited, hemizygous PLXNA3 variants and a range of neurodevelopmental disorders suggesting a novel X-linked intellectual disability syndrome. Greater understanding of PLXNA3 variant pathogenicity in humans will require additional clinical, computational, and experimental validation.
- Published
- 2022