Figure 7A displays the top 50 most frequently used search terms in this field. “Parkinson’s disease,” “alpha-synuclein,” and “short-chain fatty acids” emerged as the top three most popular terms, occurring 105, 104, and 90 times respectively, representing 7, 7, and 6% of the total keyword mentions. Following the merging of similar keywords (VOSviewer’s co-occurrence analysis using the full counting method, Unit of analysis: All keywords), Figure 7B presents the remaining 42 keywords for analysis. The gene discussed is SNCA; the disease is Parkinson disease.