The cerebellum integrates information such as the position, speed, and force at which the limbs and body are moving, all of which are necessary to carry out smooth, coordinated movements. It also is implicated in cognitive functions like language. Mice with mutations in Engrailed (En) genes display morphological defects in the cerebellum and topographic disruptions of afferent pathways as well as deficits in social interactions. These animal models will be studied to get a better understanding of how En1/2 regulate cerebellum development. A better understanding of how mutations in the Engrailed (En) genes result in a range of morphological cerebellum defects as well as disruptions of neural circuits should provide new principals to aid in the interpretation of human diseases which involve reduction in the size of the cerebellum, as well as diseases such as autism spectrum disorder (ASD) where there are more subtle structural alterations but could nevertheless have profound dysfunction of neural circuits.