Background: Autism spectrum disorder (ASD) is a complex neurodevelopmental condition characterized by social communication challenges and repetitive behaviors. Recent research has increasingly focused on the genetic underpinnings of ASD, with the Neurexin 1 (NRXN1) gene emerging as a key player. This comprehensive systematic review elucidates the contribution of NRXN1 gene variants in the pathophysiology of ASD. Methods: The protocol for this systematic review was designed a priori and was registered in the PROSPERO database (CRD42023450418). A risk of bias analysis was conducted using the Joanna Briggs Institute (JBI) critical appraisal tool. We examined various studies that link NRXN1 gene disruptions with ASD, discussing both the genotypic variability and the resulting phenotypic expressions. Results: Within this review, there was marked heterogeneity observed in ASD genotypic and phenotypic manifestations among individuals with NRXN1 mutations. The presence of NRXN1 mutations in this population emphasizes the gene’s role in synaptic function and neural connectivity. Conclusion: This review not only highlights the role of NRXN1 in the pathophysiology of ASD but also highlights the need for further research to unravel the complex genetic underpinnings of the disorder. A better knowledge about the multifaceted role of NRXN1 in ASD can provide crucial insights into the neurobiological foundations of autism and pave the way for novel therapeutic strategies.

Background: Autism spectrum disorder (ASD) is a complex neurodevelopmental condition with a rising prevalence, driven by multifactorial genetic and environmental factors. Among the genetic contributors identified, SCN2A, a critical gene encoding the Nav1.2 sodium channel, has been implicated in ASD and other related neurological conditions. This systematic review aims to explore the relationship between SCN2A mutations and ASD phenotypes. Methods: This review systematically analyzed data from studies reporting SCN2A mutations in individuals diagnosed with ASD. The primary focus was on the characterization of mutation types, associated clinical features, and phenotypic variability. Results: The mutations identified were predominantly de novo missense mutations and were associated with a spectrum of neurological and developmental challenges, including seizures, intellectual disability, movement disorders, and repetitive behaviors. A notable finding was the significant phenotypic variability observed across individuals. Gender differences emerged, suggesting a potentially greater impact on females compared to trends typically seen in ASD genetic studies. Specific mutations, such as c.2919+4delT, and mosaicism were identified as novel contributors to the observed heterogeneity. Conclusions: The review highlights the clinical significance of SCN2A mutations in ASD and highlights their relevance in genetic counseling and the development of targeted therapies. Understanding the diverse genotype–phenotype correlations associated with SCN2A can drive progress in personalized medicine, paving the way for precision therapies tailored to individuals with SCN2A-related ASD.