CYFIP1 and psychiatric disorder: Recent work has highlighted that rare complete gene knockouts in humans have a significant role in ASD and major mental illness.68 Although both deletions and duplications of CYFIP1 have been identified, total loss of CYFIP1 in humans seems unlikely as we report here that complete CYFIP1 deletion in mice leads to a failure in early embryonic development with Cyfip1-null embryos unable to survive beyond E8.5.