An analysis of changes in the mRNA levels of the genes ALDH1A1, ATP13A2, LRRK2, PARK2, PARK7, PINK1, PDHB, PPARGC1A, SNCA, and ZNF746 was performed in the peripheral blood of treated and untreated patients at the early stages of PD (stages 1-2 of the Hoehn-Yahr scale). The gene discussed is ALDH1A1; the disease is Parkinson disease.