In ASD patients, GD is represented by mucosal inflammation indicated by the increased presence of inflammatory markers (IL 6, IL 1β, TNF and monocyte chemotactic protein 1) in cerebrospinal fluid [197,199,200] and immune dysfunction in the GI tract indicated by the infiltration of immune cells such as CD3+ TNFα+ cells or CD3+ IFNγ+ cells, monocytes, and natural killer cells which produces pro-inflammatory cytokines [135,201]. This evidence concerns the gene TNF and immune system disorder.