In a mouse "FOXP2" gene knockouts, loss of both copies of the gene causes severe motor impairment related to cerebellar abnormalities and lack of ultrasonic vocalisations normally elicited when pups are removed from their mothers. These vocalizations have important communicative roles in mother-offspring interactions. Loss of one copy was associated with impairment of ultrasonic vocalisations and a modest developmental delay. Male mice on encountering female mice produce complex ultrasonic vocalisations that have characteristics of song. Mice that have the R552H point mutation carried by the KE family show cerebellar reduction and abnormal synaptic plasticity in striatal and cerebellar circuits.