Genetics versus environment in the pathophysiology of sagittal synostosis

PURPOSE: This systematic review aims to provide an updated overview of the relative contribution of germline genetic and environmental factors to the pathophysiology of sagittal craniosynostosis (sCS). METHODS: Using the PubMed database in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, relevant studies addressing genetic and/or environmental determinants of sCS in paediatric patients were systematically reviewed. RESULTS: A total of 1238 records were identified, of which 97 studies met inclusion criteria after full-text review. Overall, 25,877 patients were included, with 11,086 diagnosed with sCS (42.8%). Germline genetic variants potentially associated with craniosynostosis were reported in 251 patients, accounting for 12.6% of genetically tested individuals with sCS. Identified variants were distributed across 125 genes, with recurrent findings in 25 genes. Environmental and perinatal factors were more consistently reported across large population-based and case-control studies. Frequently associated factors included male sex, advanced maternal age, maternal smoking, thyroid dysfunction, fertility treatments, foetal constraint, prematurity, and abnormal birth weight, although effect sizes varied across studies. CONCLUSION: Identifiable germline genetic causes appear to account for only a minority of sCS cases, whereas epidemiological evidence suggests that environmental and perinatal influences may also contribute to disease pathogenesis. Nevertheless, most cases lack identifiable germline mutations in key signalling pathways, and the available evidence does not support either genetic or environmental factors as individually deterministic drivers of disease development. Overall, the evidence synthesized in this review supports a multifactorial model for sCS, in which rare genetic susceptibility and non-genetic influences likely interact in the etiopathogenesis of the condition rather than reflecting a single dominant aetiology. However, heterogeneity across studies, differences in genetic testing methodologies, potential bias in exposure assessment, and the limited availability of integrative analyses restrict definitive conclusions regarding the relative contribution of these factors.