LRRK2 p.Ile1371Val Mutation in a Case with Neuropathologically Confirmed Multi-System Atrophy.

BACKGROUND

Mutations in the leucine rich repeat kinase 2 (LRRK2) gene are among the most common genetic causes of Lewy body Parkinson's disease (PD). However, LRRK2 mutations can also lead to a variety of pathological phenotypes other than typical PD, including relatively pure nigrostriatal cell loss without alpha-synuclein-positive Lewy bodies or Lewy neurites, progressive supranuclear palsy (PSP), and multiple system atrophy (MSA). The mechanisms behind this remarkable pleomorphic pathology are currently unclear.

OBJECTIVE

To genetically and pathologically characterize a case with a LRRK2, p.Ile1371Val rare variant and pathologically proven MSA.

METHODS

From the brain donation program at the Parkinson's Institute and Clinical Center, we selected 26 brains with family history and a with clinicopathological diagnosis of PD (n = 20), MSA (n = 4), or PSP (n = 2). We performed neuropathological evaluation, including alpha-synuclein and tau immunohistochemistry and sequenced 188 genes that have been reported as causative for or associated with neurodegenerative diseases.

RESULTS

We identified a known LRRK2, p.Ile1371Val genetic variant in a case with clinically diagnosed and pathologically proven MSA. Neuropathology revealed that the olivopontocerebellar system was more affected than the striatonigral system.

CONCLUSIONS

Our data suggest that genetic variants in the LRRK2 gene can present clinically and neuropathologically as MSA. One other LRRK2 genetic variant (LRRK2, p.Ile2020Thr) has been reported with a neuropathological diagnosis of MSA. Interestingly, the LRRK2 variant (LRRK2, p.Ile1371Val) identified here has been reported previously in a postmortem case with Lewy body PD.Future studies are critical to discover the mechanisms leading to different neurodegenerative trajectories both in neuronal and glial cell populations.