Although to date, more than 500 cases of various neurological complications have been described in relation to anti-TNFa agents including CNS demyelination, Guillain-Barré syndrome, Miller Fisher syndrome, polyneuropathies, leukoencephalopathy [21, 35–44] and most of them indicate a causal association, the possible correlation between CNS demyelination and the TNFa blockade is still disputed. The gene discussed is TNF; the disease is Miller Fisher syndrome.