MORM syndrome is an autosomal recessive congenital disorder characterized by mental retardation, truncal obesity, retinal dystrophy, and micropenis". The disorder shares similar characteristics with Bardet–Biedl syndrome and Cohen syndrome, both of which are autosomal recessive genetic disorders. MORM syndrome can be distinguished from the above disorders because symptoms appear at a young age. The disorder is not dependent on sex of the offspring, both male and female offspring are equally likely to inherit the disorder. The syndrome is caused by a mutation in the INPP5E gene which can be located on chromosome 9 in humans. Further mapping resulted in the identification of a MORM syndrome locus on chromosome 9q34.3 between the genetic markers D9S158 and D9S905. Presentation
For individuals with MORM syndrome, symptoms do not appear until about one year of age. From conception to birth, individuals with MORM syndrome appear asymptotic, with no abnormal characteristics. Vision is negatively affected within the first year of life, particularly night vision. Individuals with MORM syndrome experience decreased visual acuity, meaning their ability to see distinct sharp lines decreases. Vision quality continues to deteriorate until age three. Any further reduction in vision acuity is not observed until the individual is between the ages thirty to forty. Delayed sentence processing and intellectual disability is associated with individuals with MORM syndrome, primarily observed at age four. Individuals continue to develop and grow until they are five to twelve years old.
Rapid and undesired eye motion (nystagmus) often results from the improper indication of rotational motion. Nausea, anxiety, and a general ill feeling are common due to the distorted balance signals that the brain receives from the inner ear system. Other common symptoms include tinnitus, ear ache, and a feeling of fullness in the ear. Causes
Some people will report having an upper respiratory infection (common cold) or flu prior to the onset of the symptoms of vestibular neuritis; others will have no viral symptoms prior to the vertigo attack. Some cases of vestibular neuritis are thought to be caused by an infection of the vestibular ganglion by the herpes simplex type 1 virus. However, the cause of this condition is not fully understood, and in fact, many different viruses may be capable of infecting the vestibular nerve. Acute localized ischemia of these structures also may be an important cause. Especially in children, vestibular neuritis may be preceded by symptoms of a common cold. However, the causative mechanism remains uncertain.This can also be brought on by pressure changes such as those experienced while flying or scuba diving. Mechanism
In the vestibular system, there are three canals that are semicircular in shape that input sensory clues. These canals allow the brain to sense rotational motion and linear motion changes. The brain then uses the sensory input clues and the visual input clues from the vestibular system to retain balance. The vestibulo–ocular reflex retains continuous visual focus during motion which is also the vestibular systems job during activity.