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.

Objective: The aim was to evaluate cochlear implantation (CI) outcomes in children with Down syndrome (DS) with severe-to-profound sensorineural hearing loss (SNHL), addressing a literature gap and discussing challenges including anatomical abnormalities, cognitive deficits, and Eustachian tube dysfunction. Data Sources: Systematic searches were conducted in PubMed, Web of Science, Scopus, and Embase from inception through to June 2025. Review Methods: A systematic review adhering to PRISMA guidelines was performed. Included studies reported CI outcomes in DS patients receiving otolaryngologic care for SNHL. Extracted data included findings on ear anatomy, auditory performance, speech/language development, intelligibility, and duration of CI use. Results: A total of 149 abstracts were screened, yielding six studies with 26 patients that met the inclusion criteria. The review included pediatric DS patients with documented ages at implantation spanning from 11 months to 17.9 years. CI provided significant benefits for DS patients, including improved audiometric results, enhanced environmental awareness, and psychosocial gains. Optimal outcomes were associated with early implantation, thorough preoperative imaging (CT/MRI), and management of middle ear disease. Variability in outcomes often reflected cognitive limitations and anatomical challenges such as cochlear nerve hypoplasia and Eustachian tube dysfunction. Conclusions: CI can significantly improve quality of life and communication in children with DS when tailored to their unique needs. Preoperative imaging is essential to assess candidacy, and middle ear disease should be addressed prior to surgery. Clinicians should counsel families with individualized goals that emphasize functional hearing gains over normative speech benchmarks. Broader adoption of CI in this population may be supported by standardized, population-sensitive outcome measures and future prospective studies.