Below is an instruction from Human. Write a response.
    ### Instruction:
    How many people are affected by Niemann-Pick disease ?
    ### Response:
    Niemann-Pick disease types A and B is estimated to affect 1 in 250,000 individuals. Niemann-Pick disease type A occurs more frequently among individuals of Ashkenazi (eastern and central European) Jewish descent than in the general population. The incidence within the Ashkenazi population is approximately 1 in 40,000 individuals.
    