Supplementary Material for: Augmenting Clinical Interpretability of Thiopurine Methyltransferase Laboratory Evaluation Demlova R. Mrkvicova M. Sterba J. Bernatikova H. Stary J. Sukova M. Mikuskova A. Chocholova A. Mladosievicova B. Soltysova A. 10.6084/m9.figshare.5125987.v1 https://karger.figshare.com/articles/dataset/Supplementary_Material_for_Augmenting_Clinical_Interpretability_of_Thiopurine_Methyltransferase_Laboratory_Evaluation/5125987 <b><i>Objective:</i></b> Individuals with decreased thiopurine methyltransferase (TPMT) activity are at risk of adverse effects of thiopurine administration whereas its increased activity may inactivate drugs faster. We evaluated genotype-phenotype correlations in patients with suspected hematological malignancies and inflammatory bowel disease from our region based on findings of nonlinear TPMT enzyme kinetics previously unreported. <b><i>Patients and Methods:</i></b> The study group comprised 267 individuals. They were screened for the most common variants of low TPMT activity. TPMT activity was measured in erythrocytes using the HPLC rate-blanked method. <b><i>Results:</i></b> Thirty-three patients (12.4%) were heterozygous (26 were TPMT*1/*3A, 5 TPMT*1/*2, 2 TPMT *1/*3C) and 1 was a compound heterozygote (*2/*3A). Normal and low normal TPMT activities substantially overlapped in wild-type and heterozygous individuals, whereas high activities were found in 29 wild-type genotyped patients. Extreme and life-threatening toxicity was observed in the compound heterozygote patient. <b><i>Conclusion:</i></b> Activity measurement performed at diagnosis provides clinicians with information on immediate pharmacokinetic-related adverse events and/or hypermetabolism, and genotyping may indicate the rate of pharmacodynamic thioguanine nucleotide accumulation due to slower overall thiopurine metabolism. 2014-03-12 00:00:00 Acute lymphoblastic leukemia Compound heterozygote Genotype-phenotype correlation Rate-blanked pharmacophenotyping Thiopurine methyltransferase