Congenital nystagmus is an eye movement disorder in which one or both eyes are in constant movement. It can be associated with a number of ocular or neurological diseases, or it can be inherited in an autosomal or X-linked fashion. The latter form is called idiopathic or motor nystagmus (CIN). Loci on the X chromosome (NYS1) and on 6p12 (NYS2), 7p11.2 (NYS3), and 13q31-q33 (NYS4) have been identified for CIN. The molecular characterization of NYS1 has recently been solved by Tarpey et al., who identified mutations in FRMD7, a gene of unclear function. We report five novel mutations in FRMD7 and confirm the role of this gene in the pathogenesis of X-linked congenital nystagmus.