HTT and Huntington disease: In particular, CDK5R2 encodes CDK5 which reduces the cleavage and toxicity of mutant huntingtin, HDAC3 encodes histone deacetylase 3 (see Section 4.5 below), TCERG1 encodes the transcriptional coactivator CA150 and has been linked to HD in genome-wide association studies (GWAS), PPARGC1B activates several transcription factors and nuclear receptors that are related to HD dysfunction, and MAP3K5 activates apoptotic kinase cascades in the presence of mutant huntingtin and has also been linked to HD in GWAS [27].