SYAP1 (synapse associated protein 1) is an X-linked gene with diverse cellular functions. Its primary role involves adipocyte differentiation through promotion of mTORC2-mediated phosphorylation of AKT1 at Ser-473 following growth factor stimulation 1. SYAP1 functions as an intrinsic regulator of CD59, a membrane complement regulatory protein on endothelial cells 2. The gene is expressed across most adult human tissues 3 and shows sex-dependent differences in DNA methylation and gene expression in human skeletal muscle, with differential patterns between myoblasts and myotubes 4. Disease relevance is substantial: SYAP1 expression is downregulated in approximately 50% of hepatocellular carcinoma cases 3. The gene was identified as an X-chrX-linked ASD candidate through genome-wide association analysis 5. SYAP1 is incorporated into telomere-related gene prognostic signatures for lung adenocarcinoma 6 and mast cell-related gene signatures predicting immunotherapy response 7. In the latter context, SYAP1 silencing reduced lung adenocarcinoma cell proliferation and invasion while increasing apoptosis 7. Additionally, SYAP1 was differentially expressed in diabetic wound proteomes, suggesting involvement in dysregulated healing responses 8. Clinically, SYAP1 represents a multi-functional biomarker relevant to cancer prognosis, immunotherapy prediction, and potentially autism spectrum disorder pathogenesis.