[Genetic polymorphisms of thiopurine methyltransferase and incidence of adverse events in patients with medical indication of azathioprine].

Azathioprine is a thiopurine which has a narrow therapeutic index and marked hematological and hepatic toxicity. Thiopurine s-methyltransferase is an enzyme involved in the metabolism of thiopurines. Mutations in the gene that encodes the enzyme may augment the risk of adverse events.