Introduction: Recent reports indicate that the K variant of the butyrylcholinesterase (BCHE) gene may act in synergism with the epsilon4 allele of apolipoprotein E (APOE) to increase the risk of Alzheimer's disease (AD), but this is controversial.
Material and methods: We genotyped for the BCHE-K and APOE epsilon4 alleles in a sample of 249 AD patients and 250 controls derived from the same region in a Spanish population.
Results: A protective effect of the K variant of BCHE with an odds ratio of 0.41 (95% confidence interval 0.19-0.86, P=0.02) was observed among non-APOE epsilon4 carriers, but it was limited to women.
Conclusion: Our study is the first to demonstrate that lower susceptibility to AD determined by the K variant of BCHE is dependent on gender.