SULT1A3 and Alzheimer disease: Butcher et al. (2018) evaluated association of copy number of SULT1A3/4 and the risk of AD and Parkinson’s Disease (PD; Table 1). For those individuals with less than four copies of SULT1A3/4, their ages of onset for AD were earlier, and they were more likely to develop AD (odds ratio = 1.69), but the association with PD was not significant.