Mutations in the FRMD7 gene are the cause of FRMD7-related infantile nystagmus (FIN), which is an X-linked disorder characterized by either the onset of horizontal, conjugate, gaze-dependent nystagmus in the first six months of life, or periodic alternating nystagmus.36 Patients with FIN often present with structurally normal eyes, good visual acuity, and normal colour vision.37 Here, FRMD7 is linked to pathologic nystagmus.