The test described is the Ames test, which measures damage to DNA and correlates well with carcinogenicity in vitro. It is relatively inexpensive to perform, compared to other tests of carcinogenicity, and is frequently used as a screening test for potential carcinogens. The nitroblue tetrazolium test is used to examine the ability of neutrophils to undergo a respiratory burst, and is used in the diagnosis of hereditary immunodeficiencies. The Watson-Schwaz test detects porphobilinogen in urine, and is used in the diagnosis of porphyrias. The Widal test is used to diagnose typhoid fever. Ref: Lichtman M.A., Tefferi A. (2010). Chapter 91. Primary Myelofibrosis. In J.T. Prchal, K. Kaushansky, M.A. Lichtman, T.J. Kipps, U. Seligsohn (Eds), Williams Hematology, 8e.