Below is an instruction from Human. Write a response.
    ### Instruction:
    How to diagnose Hemophagocytic lymphohistiocytosis ?
    ### Response:
    Is genetic testing available for hemophagocytic lymphohistiocytosis? Yes. Clinical genetic testing is available for the four genes known to cause familial hemophagocytic lymphohistiocytosis, types 2-5. Carrier testing for at-risk relatives and prenatal testing are possible if the two disease-causing mutations in the family are known.
    