LRRK2 and Parkinson disease: Reflecting the expected underlying neuropathology, symptomatic patients with GBA mutations, particularly those classed as severe, demonstrated RT-QuIC seeding activity most frequently (93% in PD, 100% in DLB), whereas those with homozygous autosomal recessive PD mutations did not seed any RT-QuIC responses and those with LRRK2 mutations demonstrated an intermediate frequency of seeding activity (78%; Brockmann et al., 2021).