Alpha-synuclein in salivary gland as biomarker for Parkinson's disease

Estimates of the accuracy of clinical diagnosis of Parkinson's disease (PD) range between 46% and 90%, the accuracy of diagnosis dependent on prolonged clinical observation and clinical response to levodopa. For this reason, we need reliable diagnostic biomarkers. The cardinal hallmark of PD is alpha-synuclein aggregation in the brain. Demonstrating pathological alpha-synuclein in live patients would be useful for identifying and monitoring PD patients. By autopsy studies and in vivo studies, the presence of alpha-synuclein has been demonstrated even outside the central nervous system and the gastro-enteric tract appears to be the most promising candidate tissue for biopsy-taking and the esophagus and salivary glands appear to be the area with the highest concentration of alpha-synuclein. The purpose of our study is to conduct a review to determine the utility of salivary gland biopsy for the histological diagnosis of PD. A computerized medline study was carried out through the use of pubmed: using the MeSH terms: 'salivary gland biopsy for PD', 'PD and dysphagia', 'alpha-synuclein and salivary gland'. We found 9 articles about minor salivary glands and submandibular gland biopsy for diagnosis of PD. According to the results of this review, the submandibular gland biopsy is the test with the increased sensitivity and specificity compared to the biopsy of the minor salivary glands (sensitivity: 0.85 and 0.37 respectability and specificity: 0.96 and 0.94 respectively). New studies are necessary on a wider population to confirm these results.