Multiple choice

Homozygosity for a mutation that leads to decreased activity of thiopurine methyltransferase is associated with

  1. increased activity of 6-mercaptopurine

  2. decreased activity of 6-mercaptopurine

  3. increased rate of excretion of 6-mercaptopurine

  4. decreased rate of excretion of 6-mercaptopurine

Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Decreased activity of TMPT leads to increased levels of active 6-mercaptopurine, since the drug is normally inactivated by the enzyme. This is associated with toxicity of the chemotherapeutic drug.