The expression of OR10A4, OR9A2, GRM2, and IFIT1B did not show any dependency on the H&Y scale (score ranges: 0, 1–2.5, or 3–5) (Supplementary Figure S3A–D) or UPDRS scores (Supplementary Figure S4A–D), indicating that these markers are poor indicators of PD severity. The gene discussed is OR10A4; the disease is Parkinson disease.