Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Hypophosphatemic rickets ?
    ### Response:
    Hypophosphatemic rickets (previously called vitamin D-resistant rickets) is a disorder in which the bones become painfully soft and bend easily, due to low levels of phosphate in the blood. Symptoms usually begin in early childhood and can range in severity.
    