MAP2K1 and pathologic nystagmus: CFC is characterized by dysmorphic craniofacial features, cardiac anomalies, neuromotor delay, cognitive impairment, ectodermal findings (xerosis cutis, sparse, curly and woolly or brittle hair, dystrophic nails), eye abnormalities (strabismus, nystagmus, and/or optic nerve hypoplasia) and hypotonia and is associated with alterations in BRAF, MAP2K1, MAP2K2, or KRAS genes [17].