TPMT status determination: The simplest is the most effective?

Dear Sir,We carefully read the article by Hindorf and Appell stating that genotyping should be considered the primary choice for pre-treatment evaluation of thiopurine methyltransferase (TPMT) function.1 As evidence since many years, TPMT status should be determined before a thiopurine treatment to identify patients at risk for severe adverse events, as bone marrow suppression, and to propose an individualized dosage.2 Hindorf and Appell mentioned “it is not reasonable to check both genotype and phenotype in all patients”. We agree …