Of note, we were able to see that blood citrate levels follow (by correlation analysis) closer to the factor of PD disease duration – leading metabolite, while patient age factor was positively correlating stronger with other metabolites in places prior to citrate (choline, TMAO, tyrosine, acetate, and dimethylsulfone) and also lipoprotein variable of HDL-1 subfraction signal constitute for apolipoproteins A1 (Supplementary Fig. 3). The gene discussed is APOA1; the disease is Parkinson disease.