All (4/4) targets with both a genetic association and a pre-existing approved drug had been trialed (Fig. 4C): 1 with a novel drug (CD33 in AD), 2 apparently coincidentally (BST133 and SCN2A in PD) and 1 with a repurposed drug selected at least in part based on genetic evidence (ACE in AD34). Here, CD33 is linked to Parkinson disease.