Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Lactose Intolerance ?
    ### Response:
    Four types of lactase deficiency may lead to lactose intolerance:
                
- Primary lactase deficiency, also called lactase nonpersistence, is the most common type of lactase deficiency. In people with this condition, lactase production declines over time.
    