Regarding genetic variants that alter drug metabolism, which of the following statement is true?
1) Drugs with a narrow therapeutic index, a small increase in drug levels can lead to toxicity or a small decrease in drug levels can lead to failure of drug therapy.
2) Drugs with a high therapeutic index such as warfarin are not a concern since it is not inactivated by CYP2C9.
3) Drugs with a high therapeutic index, altered rates of metabolism will have significant effects on clinical outcome.