FRMD7 (FERM domain containing 7) is an X-linked gene essential for ocular motor control and neuronal development. The protein functions as a guanyl-nucleotide exchange factor that regulates the Rho family of GTPases, particularly affecting cytoskeletal dynamics through F-actin interactions 1. FRMD7 expression is predominantly localized to the brainstem, the region governing ocular motor control 1, and influences neurite elongation, complexity, and neuronal maturation during development 2. Two functionally relevant FRMD7 isoforms (FRMD7-FL and FRMD7-S) interact during neuronal differentiation 3. Mutations in FRMD7 cause X-linked idiopathic congenital nystagmus (ICN/infantile nystagmus), the most frequent genetic cause of this oculomotor disorder 4. Over 50 mutations have been identified, with loss-of-function as the common pathogenic mechanism, predominantly affecting the FERM-C domain 5. FRMD7 mutations reduce neuronal process complexity through dysregulation of Rho GTPase signaling 2, though affected individuals show similar nystagmus parameters regardless of mutation type 5. Unlike GPR143-related nystagmus, FRMD7 mutations typically do not cause foveal hypoplasia 6. Understanding FRMD7's role in oculomotor development may guide future gene therapy approaches 4.