However, the inserts for the three thiopurines differ with respect to PGx testing for TPMT risk variants: “the genotypic test may determine the allelic profile of a patient” (azathioprine); “some laboratories perform tests to detect TMPT deficiency ... however, these tests do not identify all patients at risk for severe toxicity” (mercaptopurine); “it is recommended that the prescribing physician establish if a dose reduction is required, based on the patient response to treatment as well as on his/her genetic profile” (thioguanine). This evidence concerns the gene TPMT and hyperinsulinemic hypoglycemia, familial, 4.