By mining the available gene expression profiling data, we have found that the expression levels of Foxa1 and Foxa2, as well as Aldh1a1, Nr4a2, Aadc, Th, En1, and Slc6a3 were also down-regulated in the SNpc, but not in other brain regions or tissue samples from PD patients. The gene discussed is TH; the disease is Parkinson disease.