Quantitative analysis of nasal transcripts reveals potential biomarkers for Parkinson's disease

Patients with Parkinson's disease (PD) oftentimes develop olfactory dysfunction in their early stages, converting the nasal environment into a useful source of potential biomarkers. Here we determined the possible application of nasal fluid cells for PD biomarker identification. Thirty PD patients and 13 age-matched healthy controls were enrolled in this study. Messenger RNA levels of selected PD-related genes were monitored through real-time quantitative PCR. Target gene transcripts can be efficiently amplified from the cDNA library from human nasal fluid cell pellets. And subsequent analysis showed both a marked downregulation of parkin transcripts and an upregulation of AIMP2 in PD patients when compared to controls (cutoff value = 1.753 for with 84.2% sensitivity and 84.6% specificity; 0.359 for parkin with 76.7% sensitivity and 76.9 specificity). Moreover, alteration pattern of parkin and AIMP2 in PD was distinct from another neurodegenerative disease, multiple system atrophy. Analysis in both the early and late stages of PD cases reported that parkin levels inversely correlated with PD stages. Our results validate the practical value of easily accessible nasal fluid cells and the utility of both AIMP2 and parkin as potential biomarkers for PD diagnosis.