CASP9 and Parkinson disease: For PD, genetically predicted increased expression of PITRM1 (OR: 1.077; 95% CI: 1.009–1.149; p = 0.026) and ACAD9 (OR: 1.164; 95% CI: 1.021–1.328; p = 0.023) was associated with elevated risk, linked to mitochondrial protein degradation and electron transport chain biogenesis, while DGUOK (OR: 0.850; 95% CI: 0.769–0.940; p = 0.001) and CASP9 (OR: 0.924; 95% CI: 0.855–0.998; p = 0.045) was protective, implicating mitochondrial DNA synthesis and apoptosis regulation in mitigating movement disorders.