An atypical form of butyrylcholinesterase or the absence of its activity leads to prolonged apnea following administration of the muscle relaxant suxamethonium. BCHE and obesity in individuals with the CHE2 C5+ and CHE2 C5- phenotypes. In this retrospective analysis, Alzheimer's disease patients younger than 75 with wild-type BuChE exhibited differential efficacy to rivastigmine, while BuChE K-variant carriers experienced similar long-term treatment effects with both agents.