[Azathioprine-associated severe myelosuppression: indication of routine determination of thiopurine S-methyltransferase variant?].
BACKGROUND
Myelotoxicity is a well-known adverse effect of azathioprine, leading mainly to leukopenia. Other azathioprine associated hematological adverse effects are uncommon.


METHODS
We report a 49-year-old woman with rheumatoid arthritis and acquired hemophilia, who presented a severe myelosuppression occurring 3 weeks after an increase of her azathioprine regimen (at a daily dose of 150 mg). The patient had a heterozygous mutation of the thiopurine S-methyltransferase gene (TPMT*3A). Azathioprine therapy was discontinued and she recovered at 3 weeks. The patient had no relapse of pancytopenia after a 1 year follow-up.


CONCLUSIONS
Routine measurement of TPMT activity or determination of TPMT variant allele may be useful tests, in order to identify the subgroup of patients who are at risk to develop azathioprine induced severe myelosuppression.
Ngo
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Département de médecine interne, CHU de Rouen, 1 rue de Germont, Rouen cedex, France.
Sauvetre
G
G
Vittecoq
O
O
Lévesque
H
H
Marie
I
I
D018501:Antirheumatic Agents / Q000009:adverse effects*; D001379:Azathioprine / Q000009:adverse effects*; D005260:Female; D006801:Humans; D008780:Methyltransferases / Q000097:blood* / Q000235:genetics; D008875:Middle Aged; D009154:Mutation; D010198:Pancytopenia / Q000139:chemically induced*
D018501:Antirheumatic Agents; D008780:Methyltransferases; C022745:thiopurine methyltransferase; D001379:Azathioprine