MAPT and Parkinson disease: LRRK2 pathological mutations are autosomal dominant and, importantly, PD patients carrying LRRK2 mutations are clinically and neuropathologically indistinguishable from idiopathic patients, although they exhibit a prevalence of tau aggregates [4], supporting the idea that the elucidation of the physiological and pathological role of LRRK2 may strongly contribute to the discovery of the molecular mechanisms of neurodegeneration in PD, possibly leading to new therapeutical approaches.