Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Medullary Sponge Kidney ?
    ### Response:
    Medullary sponge kidney, also known as Cacchi-Ricci disease, is a birth defect where changes occur in the tubules, or tiny tubes, inside a fetus kidneys.
                
In a normal kidney, urine flows through these tubules as the kidney is being formed during a fetus growth.
    