RAC1 and autism: This is especially true as studies using transgenic mice with a constitutively active form of RAC1 show overproduction of small abnormal supernumerary spines [43,50,51], indicating that overproduction of RAC1 in BA9 of both children and adults with autism is evidence of overabundance of active and abnormal neuronal spines in the brains of people with autism examined in this study.