Below is an instruction from Human. Write a response.
    ### Instruction:
    How to diagnose Imerslund-Grasbeck syndrome ?
    ### Response:
    How is Imerslund-Grasbeck syndrome diagnosed? The diagnosis of Imerslund-Grasbeck syndrome (IGS) is made after a series of tests are performed. Cobalamin deficiency is typically detected first, followed by showing that cobalamin is poorly absorbed (the main cause of cobalamin deficiency).
    