In scRNA-seq analysis, MECR shows the most significant decrease in neurons from PD patients, and is also significantly downregulated in the vulnerable subpopulation of ventral DA neurons (SLC18A2+SOX6+AGTR1+), suggesting that MECR may contribute to impaired mitochondrial function, resulting in reduced energy production and heightened neuronal vulnerability to stress. This evidence concerns the gene SLC18A2 and Parkinson disease.