In addition, mHTT disrupts mitochondrial trafficking and the balance between fission and fusion, reducing ATP and impairing bioenergetics [214], which has been associated with increased dynamin-related protein 1 (DRP1) and mitochondrial fission 1 (FIS1), and decreased levels of mitofusin 1 and 2 (MFN 1 and 2) and the optic atrophy 1 (OPA1) observed in the striatum and cortex of HD patients [215,216]. This evidence concerns the gene FIS1 and Huntington disease.