Background:Neuromyelitis optica (NMO) and multiple sclerosis (MS) are autoimmune diseases of the central nervous system with complex pathogeneses. NMO was once considered to be a severe variant of MS. There has been more evidence that a non-synonymous exchange (rs763361/Gly307Ser) in the gene for CD226 is linked to several autoimmune diseases including multiple sclerosis (MS). However, no studies have investigated the role of rs763361 in the pathogenesis of NMO.Objectives:The goal of our study is to evaluate the role of CD226 Gly307Ser in neuromyelitis optica (NMO) in Southern Han Chinese.Methods:Eight-nine NMO patients, 93 relapsing-remitting multiple sclerosis (RRMS) patients, and 122 controls (CTLs) were enrolled. The rs763361 alleles of the subjects were determined by sequencing-based typing.Results:The results strongly support that the TT genotypes are associated with NMO but are not significantly correlated with susceptibility for MS.Conclusions:CD226 Gly307Ser may correlate with risk of NMO in Southern Han Chinese.