Below is an instruction from Human. Write a response.
    ### Instruction:
    How many people are affected by 21-hydroxylase deficiency ?
    ### Response:
    The classic forms of 21-hydroxylase deficiency occur in 1 in 15,000 newborns. The prevalence of the non-classic form of 21-hydroxylase deficiency is estimated to be 1 in 1,000 individuals. The prevalence of both classic and non-classic forms varies among different ethnic populations.
    