CELSR1 and Exotropia: Both father and son in Family 12, affected with intermittent exotropia, had missense mutations in CELSR1. CELSR1 encodes a protein of the Flamingo subfamily, part of the cadherin superfamily, which is widely expressed in the nervous system and plays critical roles in early neurodevelopment, including axon guidance, neuronal migration, and cilium polarity [24].