While there are no published studies on the relationship of ApoE4 expression in humans and SirT1 levels, perhaps due to the design requirements for such studies, it was also reported in Theendakara et al. 10 that SirT1 is significantly lower in post-mortem temporoparietal regions of AD brain as compared to cognitively normal controls. The gene discussed is SIRT1; the disease is Alzheimer disease.