In the case of optic neuritis, the optic nerve becomes swollen, and its function is impaired. Inflammation of the optic nerve causes loss of vision because of the swelling and destruction of the protective myelin sheath that covers and insulates the optic nerve.
Various alterations in corresponding genes affect the levels of serotonin or sensitivity to serotonin and may cause behavioral changes. Changes in serotonin level can affect behavior. The level of serotonin is controlled by multiple mechanisms.Any changes in the genes involved may lead to serious consequences.everal genetic alterations in the gene for tryptophan hydroxylase were reported to be associated with suicidal behavior. This enzyme is involved in biosynthesis of serotonin, and therefore its genetic alterations can easily affect the level of this mediator.
Some single genes have major consequences for behavior. A single genes usually makes a single protein, or sometimes only a part of a protein (for example, it takes the products of 4 different genes to produce a single acetylcholine receptor/channel).A typical cell expresses ~10,000 different gene products.irtually any known gene can be expressed in cells and its function studied. Once the sequence of a gene is known the gene can be amplified with PCR or by growing it in bacteria. The gene can then be linked to a promoter and placed into a circular piece of DNA, which is then placed into cells by a variety of methods.