Overview of the leukotriene pathway, demonstrating the key enzymes encoded by genes with variants associated with asthma, aspirin intolerant asthma, or the pharmacologic response to leukotriene modifier therapy. Highlighted boxes in red demonstrate known genetic associations. AERD = association with aspirin exacerbated respiratory disease, PG = pharmacogenetic association. (Modified from Drazen, et al, N Engl J Med, 1999)