LRRK2 and Parkinson disease: However, genetic forms of Alzheimer's and Parkinson's diseases (AD and PD, respectively) are due to mutations in a variety of conceptually distant molecular elements (proteases, such as the presenilins; kinases, such as PINK1 and LRRK2; ubiquitin-ligases, such as Parkin; redox-sensitive chaperones, such as DJ-1), all converging in mitochondrial dysfunction as the cellular trigger of neuronal cell death.