Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) vitamin D-dependent rickets ?
    ### Response:
    Vitamin D-dependent rickets is a disorder of bone development that leads to softening and weakening of the bones (rickets). The condition is split into two major types: type 1 (VDDR1), which is also known as pseudovitamin D deficiency rickets or vitamin D 1-hydroxylase deficiency, and type 2 (VDDR2), also known as hereditary vitamin D-resistant rickets (HVDRR).
    