and three large introns [22]. Although more than 65 BCHE mutations have been identified, not all of them have been fully studied [23]. In general, these mutations produce enzymes with lower levels of catalytic activity than that of those produced by wild-type mutations [24]. BChE has also been tested as a novel therapeutic agent for cocaine dependence: a quadruple mutant hydrolase derived from human BChE suppressed cocaine toxicity and abolished drug-primed reinstatement in rats [25]. Our working hypothesis is that polymorphisms in BCHE lead to various enzyme profiles that allow different concentrations of cocaine to reach the reward system in the brain, thereby increasing or decreasing susceptibility to developing addictive behaviors.
