In a small hippocampal mRNA profiling study of six AD versus two control brains, Li et al. [15] detected lower GSTO1 (glutathione S-transferase omega-1) levels in the AD brains, followed by significant associations with age-at-onset of both AD and Parkinson’s disease with variants in both GSTO1 and its nearby homologue GSTO2 [28]. The gene discussed is GSTO1; the disease is Parkinson disease.