[Allelic variants of TPMT and the risk of leucopenia and neutropenia in patients treated for acute leukaemia].

Aim: The objective of this study was to analyse the influence of TPMT genetic polymorphism on the occurrence of therapeutical adverse effects such as hematological disorders, leucopenia and neutropenia after thiopurines administration.

Material And Methods: The examined group consisted of 210 patients (121 boys, 89 girls) aged between 1 and 18 (median age 7 years, average age 8 years, SD+/-5.32) treated for leukaemia (acute lymphoblastic leukaemia ALL: n=167; acute myeloblastic leukaemia AML: n=43). Analysis of treatment adverse reactions in every child was performed according to the WHO toxicity scale, during the entire length of observation period and in particular stages (6 stages).

Results: Analysis of changes in selected blood count parameters in the whole treatment period in the acute leukaemia group indicated that in the TPMT *2, *3A or *3C polymorphism carriers' group there is a statistically significant decrease in the white blood cell count (p=0.0025) and in the neutrophil count (p=0.019). Detailed assessment in particular treatment periods indicated that increased leukopenia in TPMT heterozygotes occurred significantly more frequently only in early re-induction period (p=0.012).

Conclusion: Thiopurines administration is related to the increase in hemato-oncological treatment toxicity in TPMT heterozygotes.