In addiction, Lucchinetti [56] and Roemer [80] and their groups have independently performed detailed comparative study between NMO and MS lesions: in particular, in contrast to NMO, they revealed that AQP4 immunoreactivity was variable in MS lesions (AQP4 is diffusely increased in the white matter of active lesions, whereas chronic inactive lesions are devoid of AQP4). This evidence concerns the gene AQP4 and neuromyelitis optica.