The present invention relates to methods of treating or preventing a complement-mediated disease and/or disorder in a subject with a complement C5 polymorphism, including administering to a subject in need thereof a therapeutically or prophylactically effective amount of an agent that a) inhibits the classical complement pathway, the alternative complement pathway and the lectin complement pathway; and/or b) inhibits eicosanoid activity. The invention also relates to methods of identifying patient populations with C5 polymorphisms that are treatable with specific agents that a) inhibit the classical complement pathway, the alternative complement pathway and the lectin complement pathway; and/or b) inhibit eicosanoid activity.