Selectively increased autofluorescence at fingernails and certain regions of skin: A potential novel diagnostic biomarker for Parkinson’s disease

Diagnosis of Parkinson’s disease (PD) mainly relies on the judgment of experienced neurologists on the clinical symptoms of patients. Quantitative and specific biomarker tests for PD is greatly needed. In this study we tested our hypothesis that increased autofluorescence (AF) of skin and fingernails may become a novel diagnostic biomarker for PD. Our study has indicated that PD patients have a distinct pattern of AF changes, compared with that of acute ischemic stroke (AIS) patients: First, the AF intensity of PD patients in the fingernails and a part of the examined regions of skin is significantly higher than that of the healthy and Low-Risk group, while the AF intensity of AIS patients is significantly higher than that of the healthy and Low-Risk group in most regions examined; second, there is AF asymmetry at the index fingernails and two regions of the skin of PD patients, while there is AF asymmetry at all examined regions of AIS patients; and third, both the AF intensity and AF asymmetry at Centremetacarpus of PD patients is significantly lower than those of AIS patients. The increased AF may result from the altered keratins’ AF induced by the oxidative stress in the plasma of PD patients. Collectively, our study has indicated that PD patients have a distinct pattern of AF changes compared with those of healthy and Low-Risk persons as well as AIS patients, which may become a novel diagnostic biomarker for PD.