LRRK2 and Parkinson disease: Although LRRK2-PD is often said to be clinically indistinguishable from “idiopathic” PD, the MDSGene database (https://www.mdsgene.org) interestingly reveals that a substantial proportion of patients with pathogenic or likely pathogenic LRRK2 variants (265/863 = 31%) had early-onset PD (EOPD, defined as motor symptom onset below age 50 years).