CX3CL1 and relapsing-remitting multiple sclerosis: Increased FKN levels are present in cerebrospinal fluid and serum of patients with relapsing-remitting MS (Kastenbauer et al., 2003) and comparison of MS and healthy post-mortem brains revealed the presence of a hypermethylation mark in the FKN loci that correlated with decreased FKN transcript levels in demyelinated lesions (Huynh et al., 2014).