Cross-Ethnic Variant Screening and Burden Analysis of PTPA in Parkinson's Disease

Background: Recently, homozygous variants in PTPA were identified as the disease cause for two pedigrees with early-onset parkinsonism and intellectual disability. Although the initial link between PTPA and parkinsonism has been established, further replication was still necessary.

Objectives: To evaluate the genetic role of PTPA in Parkinson's disease (PD).

Methods: We analyzed rare variants of PTPA in cohorts of Asian and European ancestries (N_case = 2743, N_control = 8177) with whole-exome sequencing, and further explored the functional effect of the target variant.

Results: One patient with early-onset PD from a consanguineous family carried the homozygous variant p.Met329Val, while her parents and elder sister with heterozygous p.Met329Val were healthy. This patient developed minor cognitive decline within 1 year, with a Montreal Cognitive Assessment (MoCA) score dropping from 28 to 25. Functional exploration with overexpression studies suggested that this variant was associated with decreased protein Phosphatase 2A (PTPA) protein level by affecting protein stability, but not mRNA expression.

Conclusions: These results have broadened the mutation spectrum of PTPA, and paved the way for further research into the role of PTPA in PD. © 2023 International Parkinson and Movement Disorder Society.

PTPA; Parkinson's disease; protein level; rare variant.