Below is an instruction from Human. Write a response.
    ### Instruction:
    How many people are affected by Usher syndrome ?
    ### Response:
    Usher syndrome is thought to be responsible for 3 percent to 6 percent of all childhood deafness and about 50 percent of deaf-blindness in adults. Usher syndrome type I is estimated to occur in at least 4 per 100,000 people. It may be more common in certain ethnic populations, such as people with Ashkenazi (central and eastern European) Jewish ancestry and the Acadian population in Louisiana.
    