A Patient With Miller Fisher Syndrome With Positive GQ1b and Aquaporin-4 Antibodies: Will There Be an Aquaporin-4 Antibody Associated Disorder?

There have been many advancements in the field of neuromyelitis optica and neuromyelitis optica spectrum disorder since the discovery of aquaporin-4 (AQP4) and myelin oligodendrocyte glycoprotein antibodies. It is also recognized that the pathological features associated with myelin oligodendrocyte glycoprotein antibodies are beyond the domain of neuromyelitis optica spectrum disorder and there is a separate nomenclature, namely myelin oligodendrocyte glycoprotein antibody associated disease. Currently, there is no aquaporin-4 antibody associated disorder, even though aquaporin-4 antibodies are not as widely present in other disorders.  Miller Fisher syndrome (MFS) is a variant of Guillain Barré syndrome, in which there are positive GQ1b antibodies with no evidence of myelitis or optic neuritis. MFS is not considered a component of neuromyelitis optica spectrum disorder. We report on a patient with MFS that was positive for GQ1b and aquaporin-4 antibodies but negative for myelin oligodendrocyte glycoprotein antibodies and is devoid of any features of neuromyelitis optica spectrum disorder. This finding may lead to investigations and reports of other pathologies that are associated with the aquaporin-4 antibody.