MECP2 and Global developmental delay: Key cognitive-related genes, such as SYNGAP1, GRIN2B, GRIN1, DLG4, SCN2A, ADNP, MECP2, and EP300, played central roles in the GDD network (eFigure 5 in Supplement 1), influencing brain development and function and ultimately contributing to the core symptoms of GDD (eFigure 6 in Supplement 1).