Ushers
The most common type of deaf-blindness disease in the world is Usher Syndrome. Usher Syndrome is a clinically and genetically heterogeneous disease. It is inherited in an autosomal recessive inheritance pattern. Worldwide, the chance of a baby being born with Ushers Syndrome is approximately 1 in every 25,000 babies. To date, there are roughly 50,000 people with Ushers Syndrome living in the United States. As stated above, Ushers Syndrome is an inherited disease characterized by hearing impairment and progressive vision loss. The vision loss is due to retinitis pigmentosa, which is a degenerative condition of the retina and this usually appears during adolescence or early adulthood. The balance of an individual is usually also affected with retinitis pigmentosa. The other part of Usher Syndrome, the hearing loss, is due to a genetic mutation affecting nerve cells in the cochlea, a sound transmitting structure in the inner ear. The same genetic effect also adversely affects photoreceptor cells in the retina leading to vision loss. Usher Syndrome is a heterogeneous disease meaning it comes in several different types, in our case 3 and they are called Usher Syndrome 1, Usher Syndrome 2, and Usher Syndrome 3. They are numbered in decreasing range of severity. USH1 patients are deaf at birth and onset of retinitis pigmentosa is prepubertal and most of them have vestibular dysfunction. USH2, on the other hand is characterized by a moderate to severe hearing loss at birth and to retinitis pigmentosa can be diagnosed at puberty. USH3 is further down the chain meaning these same symptoms apply but they actually show up later on in life. Usher Syndrome can also be associated with reduced odor identification, impaired sperm mobility and mental deficiency. Of the eleven loci responsible for this syndrome, nine have already been identified. The proteins that are encoded by these genes are actually part of a dynamic protein complex that occurs in the hair cells of the inner