Below is an instruction from Human. Write a response.
    ### Instruction:
    How many people are affected by Imerslund-Grsbeck syndrome ?
    ### Response:
    Imerslund-Grsbeck syndrome is a rare condition that was first described in Finland and Norway; in these regions, the condition is estimated to affect 1 in 200,000 people. The condition has also been reported in other countries worldwide; its prevalence in these countries is unknown.
    