CDK5 and juvenile Huntington disease: Accordingly, dysregulation of Cdk5 has been observed in numerous brain diseases, including schizophrenia and epilepsy (Patel et al., 2004; Engmann et al., 2011) and neurodegenerative disorders, including Huntington’s disease, Alzheimer’s disease and Amyotrophic Lateral Sclerosis (ALS) (Cheung and Ip, 2012).