Ear and ear canal anomalies are also related to this structure of the ear and are known to be associated with sensorineural hearing loss and conductive hearing loss. Vertigo refers to the inappropriate perception of motion. This is due to dysfunction of the vestibular system. One common type of vertigo is benign paroxysmal positional vertigo, when an otolith is displaced from the ventricles to the semicircular canal. The displaced otolith rests on the cupola, causing a sensation of movement when there is none. Ménière's disease, labyrinthitis, strokes, and other infective and congenital diseases may also result in the perception of vertigo.
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