Combined with the CSF mononuclear cells, MRI results (although the MRI of Patient 2 exhibited certain atypical features that deviate from the classical presentation of encephalitis, considering her clinical manifestation and the increase of monocyte in CSF, we still considered that she was encephalitis with white matter involvement), and serum MOG-IgG antibodies, we considered that the M. pneumoniae infections induced MOG-IgG-associated encephalitis. This evidence concerns the gene MOG and encephalitis.