CCR5 and multiple sclerosis: CCR-5Δ32 is a 32-base-pair deletion within thecoding region of CCR-5, which results in a frame shift and generates anonfunctional receptor [11].Homozygous expression of CCR-5Δ32 is associated with a reduced risk ofasthma and with a reduced severity of rheumatoid arthritis [17, 18],multiple sclerosis [19, 20], and primary biliary cirrhosis (PBC) [21].