We encountered some new clinical features in the present study, including; behavior problems such as self-injurious, aggressive behavior, agitation, and stressfulness, and some dysmorphic characteristics such as a long thin face, strabismus (hypertropia type), low set ears, wide nasal bone, and severe toe deformity, not previously reported for L1 syndrome or other L1CAM gene mutations. Here, L1CAM is linked to L1 syndrome.