LRRK2 and Parkinson disease: The leucine-rich repeat kinase 2 (LRRK2) is a large multi-domain protein that belongs to the family of tyrosine kinases-like (TKL) protein kinases1, and mutations of the LRRK2 gene have been identified as one of the genetic causes of Parkinson’s disease (PD), the second most common progressive neurodegenerative disorder2,3.