ARHGAP21 (Rho GTPase Activating Protein 21): This gene encodes a protein involved in the regulation of Rho GTPases, a family of proteins that play a key role in regulating the actin cytoskeleton, cell shape, and motility. ARHGAP21 is implicated in various cellular processes, including intracellular trafficking and cell migration, and has potential links to neurological disorders....