Genes involved in this study included AD risk genes (for example Aconitase 1 or ACO1; Lipoprotein A or LPA; Periostin or POSTN; Structural maintenance of chromosomes protein 5 or SMC5) or PD risk genes (Fibroblast Growth Factor 20 or FGF20; leucine rich repeat kinase 2 or LRRK2; 2-Hydroxyacyl-CoA Lyase 1 or HACL1). The gene discussed is SMC5; the disease is Parkinson disease.