In the News story ‘Geneticists tap human knockouts’ (Nature 514, 548; 2014), the team investigating knockouts found some 200,000 variations that knocked out genes (not 150,000 genes, as stated). In addition, the team that studied 36,000 Finnish people was not led by Daniel MacArthur, he was just a member of the group. Although Marfan syndrome can cause serious heart problems, it rarely results in sudden heart failure. Finally, Bing Yu is a woman not a man.