In clinical trials, bosentan was shown to cause significant drug-induced liver injury (DILI) in some patients. Because it is not possible to identify those at higher risk for DILI, all patients to be treated with bosentan must enroll in a program requiring documentation of liver blood testing before they can receive the drug. Because this program is costly and is perceived as onerous, a genetic test capable of identifying susceptible individuals would probably be rapidly adopted by physicians.