Usher syndrome - "a genetic disease causing deaf and blindness." A simple definition. In essence, this disease slowly blinds you by progressive retinis pigmentosa, as well as ruin your hearing through congenital hearing loss. This particular disease can only be inherited, and is uncommon becuase it is a recessive trait. It can occur in an estimated 1 in 11,000 people.
"Usher Syndrome" is not a name which best describes or reflects its signs and symptoms. It was named this becuase of C.H. Usher, a British ophthalmologist. He wrote about the disease when it was unknown, and described cases in which there was a clear link between congenital deafness and retinis pigmentosa. This was long ago, and he was ahead of his time, as the paper was writtin in 1914.
This condition has three seperate types; Usher Syndrome I, II and III. I is the most unfair, as the child is born almost completely deaf, and eyesight begins to fail after about age 10. In type II, eyesight does not tend to degrade until later in life, but the child is born hard of hearing. Type III syndrome is the most common, wherein loss of sight and hearing occurs much later in life.
The USH3A gene is responsible for creating a protien that is essential in the development and upkeep of the retina and inner ear. Usher syndrome type III is a result of a mutation whithin this gene, however, the full explanation as to the protiens role in vision and hearing loss, is yet to be discovered.