Ménière's disease turn, is strongly associated with developing MD, but not everyone with EH develops MD: "The relationship between endolymphatic hydrops and Meniere's disease is not a simple, ideal correlation." Additionally, in fully developed MD the balance system (vestibular system) and the hearing system (cochlea) of the inner ear are affected, but there are cases where EH affects only one of the two systems strong enough to cause symptoms. The corresponding subtypes of MD are called "vestibular MD", showing symptoms of vertigo, and "cochlear MD", showing symptoms of hearing loss and tinnitus. The mechanism of MD is not fully explained by EH,
Niemann–Pick disease, SMPD1-associated Niemann–Pick disease, SMPD1-associated Niemann–Pick disease, SMPD1-associated refers to two different types of Niemann–Pick disease which are associated with the SMPD1 gene. There are approximately 1,200 cases of NPA and NPB worldwide with the majority of cases being Type B or an intermediate form. Descriptions of type E and type F have been published, but they are not well characterized, and are currently classified under type B. Mutations in the SMPD1 gene cause Niemann–Pick Types A and B. This gene carries instructions for cells to produce a lysosomal enzyme called acid sphingomyelinase. Insufficient activity of the enzyme acid sphingomyelinase causes the