“Instead of shooting arrows in the dark to find a drug that would be beneficial, we can now make an informed choice about the beneficial and harmful effects of pharmacological inhibition of a wide range of pathways,” comments Danish Saleheen, MBBS, PhD, one of the lead authors of a major study in Nature this week. An international research collaborative team studied more than 1,800 individuals who carried loss-of-function mutations in both copies of their genes, so-called “human knockouts."