Recent studies have suggested that diminished Ccr5 functioning has an effect on synaptic plasticity and hippocampal memory in mouse models. CCR5-delta32, a 32-bp frameshift deletion in human CCR5 encoding a nonfunctional receptor, has been reported to have a protective effect against human immunodeficiency virus infection but its role as a modifier of neurodegenerative disease has been minimally explored. We investigated whether the CCR5-delta32 polymorphism could have an effect in the context of human neurodegenerative diseases.