Azathioprine-induced myelosuppression due to thiopurine methyltransferase deficiency in a patient with autoimmune hepatitis.
Azathioprine can cause severe myelosuppression. The inherited activity of the enzyme thiopurine methyltransferase has been recently recognised as a major factor in the susceptibility to myelosuppression. Thiopurine methyltransferase deficiency occurs at a frequency of one in 300 and is associated with profound myelosuppression after a short course of azathioprine. Very low thiopurine methyltransferase activity represents the TPMTL/TPMTL genotype, and can be detected before therapy with azathioprine is started. We describe the first documented case of azathioprine-induced severe myelosuppression due to thiopurine methyltransferase deficiency in autoimmune liver disease. The azathioprine dose was low (1 mg/kg) and pancytopenia occurred after 56 days therapy. It would be advisable to measure thiopurine methyltransferase activity before patients with autoimmune hepatitis are exposed to azathioprine.
Ben Ari
Z
Z
Liver Transplantation Unit, Royal Free Hospital, Hampstead, London, UK.
Mehta
A
A
Lennard
L
L
Burroughs
A K
AK
D000328:Adult; D001327:Autoimmune Diseases / Q000150:complications* / Q000188:drug therapy / Q000378:metabolism; D001379:Azathioprine / Q000009:adverse effects*; D001855:Bone Marrow Diseases / Q000209:etiology*; D006505:Hepatitis / Q000150:complications* / Q000188:drug therapy / Q000378:metabolism; D006801:Humans; D007166:Immunosuppressive Agents / Q000009:adverse effects*; D008297:Male; D008780:Methyltransferases / Q000172:deficiency*; D010198:Pancytopenia / Q000139:chemically induced
D007166:Immunosuppressive Agents; D008780:Methyltransferases; C022745:thiopurine methyltransferase; D001379:Azathioprine