Fatal Myelotoxicity After Azathioprine Treatment

Abstract

Azathioprine and 6-mercaptopurine have been used for many years in the treatment of inflammatory bowel disease. Approximately 0.3% of the population are homozygous for variant alleles associated with extremely low thiopurine S-methyltransferase enzyme activity. We describe the case of a young patient with ulcerative colitis, homozygous for TPMT∗3A alleles, who suffered fatal azathioprine-induced myelotoxicity after standard dosing with azathioprine. Screening for decreased activity of TPMT in patients prior to azathioprine treatment is advised to minimize the risk of drug-induced toxicity.

Keywords:

• Ulcerative colitis
• azathioprine
• myelotoxicity
• poor metabolizer
• pharmacogenetics
• thiopurine S-methyltransferase

This research was supported by grants No: IGA MZČR NR9094, and MSM0021620849.