Functional Analyses of Two Novel LRRK2 Pathogenic Variants in Familial Parkinson′s Disease

Background Pathogenic variants in the LRRK2 gene are a common monogenic cause of Parkinson’s disease. However, only seven variants have been confirmed to be pathogenic. Objectives We identified two novel LRRK2 variants (H230R and A1440P) and performed functional testing. Methods We transiently expressed wildtype, the two new variants, or two known pathogenic mutants (G2019S and R1441G), in HEK-293T cells, with or without LRRK2 kinase inhibitor treatment. We characterized the phosphorylation and kinase activity of the mutants by western blotting. Thermal shift assays were performed to determine the folding and stability of the LRRK2 proteins. Results The two variants were found in two large families and segregate with the disease. They display altered LRRK2 phosphorylation and kinase activity. Conclusions We identified two novel LRRK2 variants which segregate with the disease. The results of functional testing lead us to propose these two variants as novel causative mutations for familial Parkinson’s disease.