Additionally, the measurement of the ratios of key proteins acting upstream (HO-1) or downstream (oligomeric or total α-synuclein) of miR-153 or miR-223 to these miRNA expression levels did not improve the accuracy of the test as a PD neurodiagnostic relative to the ascertainment of miR-153 or miR-223 alone [19]. Here, SNCA is linked to Parkinson disease.