The invention relates to a method of determining whether an individual has Parkinson's
disease, the method comprising: determining the level of markers in a bodily fluid sample from the individual, wherein the markers comprise
Protein disulphide
isomerase A1 (PDIA1),
Protein disulphide
isomerase A3 (PDIA3), Mesencephalic
astrocyte-derived neurotrophic factor (MANF) and
clusterin; wherein an increase in the level of PDIA1, MANF, and
clusterin, and decrease in the level of PDIA3 relative to a
reference level in combination with the individual's
age and gender, is indicative of the individual having Parkinson's
disease; and associated compositions, uses and methods.