Frequency of the D620N mutation in VPS35 in Parkinson disease.

Objective: To evaluate the frequency and clinical spectrum of the recently identified p.D620N mutation in the VPS35 gene in Parkinson disease (PD) in an international sample.

Design: Genetic analysis by DNA sequencing and detailed clinical and neuropsychiatric assessment as well as neuroimaging in mutation carriers.

Setting: Tertiary referral centers in Germany, Serbia, Chile, and the United States.

Patients: One thousand seven hundred seventy-four patients with PD.

Main outcome measure: Frequency of the p.D620N mutation.

Results: A single mutation carrier was identified. The mutation carrier was a 60-year-old German man who had tremor-dominant PD since the age of 45 years. Longitudinal follow-up over 13 years revealed a disease progression from Hoehn and Yahr stage 1 to 3. There was evidence of mild cognitive impairment on the Montreal Cognitive Assessment. No abnormalities were observed by multimodal neuroimaging. He had a family history consistent with autosomal dominant inheritance. An affected paternal aunt and 3 reportedly unaffected siblings were also found to be mutation carriers.

Conclusion: VPS35 mutations are a rare cause of PD in different populations. The clinical phenotype may be indistinguishable from idiopathic PD with the possible exception of an earlier age at onset. Genetic analysis of the extended family revealed incomplete penetrance of the p.D620N mutation.