Some reported possible biomarkers in the early diagnosis of PD
| Biochemical/histopathology markers | |
| Rectal/colonic biopsy | Phosphorylated α-synuclein-positive Lewy neurites; α-synuclein-positive nerve fibres (figure 1) |
| Skin biopsy | α-Synuclein accumulation |
| Gastric biopsy | Phosphorylated α-synuclein-positive Lewy neurites |
| Low uric acid | Proposed |
| Low-density lipoprotein/serum cholesterol | Proposed |
| Genetic markers | |
| Leucine-rich repeat kinase 2 mutation (G2019S) | |
| Glucocerebrosidase mutation | |
| Imaging markers | |
| Transcranial sonography | |
| DAT scan | |
| The above two can be used in conjunction with clinical symptoms such as hyposmia or REM sleep behaviour disorder | |
| Clinical markers combined with imaging | |
| NMSQuest, SCOPA AUT, smell-identification test (figure 2) and transcranial sonography—can be used as marker with 95.8% sensitivity in PD7 | |
PD, Parkinson's disease; NMSQ, Non-Motor Symptoms Questionnaire; SCOPA AUT, SCOPA autonomic scale.