This proposal is supported by differences in the overt speech phenotypes across these different disorders – FOXP2 mutation is associated with profound oromotor dyspraxia plus higher order language impairments, whereas oromotor impairments are subtle in Rolandic epilepsy and are not common within the heterogeneous population of individuals diagnosed with specific language impairments of unknown aetiology. This evidence concerns the gene FOXP2 and Rolandic epilepsy.