Genetic Analysis of the X Chromosome Associates Loci with Progression of Parkinson's Disease

Background: Genetic variants on the X chromosome have been linked to susceptibility for Parkinson's disease (PD), but their roles in disease progression remain unclear. Objectives: This study investigated associations between X chromosome variants and longitudinal cognitive decline or motor impairment in patients with PD. Methods: We conducted combined (male + female) and stratified X-chromosome-wide survival studies (XWSS) in 4467 patients with PD with 33,406 longitudinal visits. Cognitive decline was defined as global cognitive impairment (GCI, Mini Mental State Exam score ≤25), whereas motor impairment was evaluated by Hoehn and Yahr stage 3 (HY3). Expression quantitative trait locus (eQTL) and genetic colocalization analyses were systematically performed. Results: We identified 40 common variants in the X-chromosome-wide screen associated with longitudinal progression of PD with P-value <9.27 × 10⁻⁶, including 11 independent loci associated with cognitive decline and two with motor impairment. The rs142724191 and rs144112368 variants were associated with cognitive decline in both combined and male-only analyses. rs111708875 reached genome-wide significance for motor progression in female cases (hazard ratio [HR] = 3.98, 95% confidence interval [CI]: 2.54–6.25) with P-value = 1.84 × 10⁻⁹. All these variants were independent with X chromosome susceptibility loci associated with PD, Alzheimer's disease, or Lewy body dementia. Conclusions: Our XWSS identified novel genetic progression-associated loci on the X chromosome for PD, providing new insights into the X chromosome-linked genetic underpinnings of PD.