Final answer:
Variants in CYP2D6 cause decreased enzyme function. True
Step-by-step explanation:
The statement that variants in CYP2D6 cause decreased enzyme function is True. CYP2D6 is an enzyme that plays a crucial role in drug metabolism, specifically in the breakdown of many medications. Genetic variations in CYP2D6 can lead to impaired enzyme function, resulting in altered drug metabolism and potential therapeutic consequences.