[Aplasia after azathioprine administration: role of the thiopurine methyltransferase genetic polymorphism].
BACKGROUND
Azathioprine is an immunosuppressor drug widely used in the treatment of autoimmune diseases. Adverse effects during treatment are related to the activity of thiopurine methyltransferase (TPMT), an enzyme which plays a role in azathioprine metabolism. The presence of the allelic variants of the TPMT gene allows us to classify patients into three different groups: high, moderate and low risk of myelosuppression after receiving standard doses of azathioprine.


METHODS
Study of the allelic variants of the TPMT gene in the positions 460 and 719 with PCR methods in a patient with Crohn's disease, who developed aplasia after receiving azathioprine. The study was extended to his relatives.


RESULTS
The patient under study carried the most frequent variant allele of the TPMT gene associated with low enzymatic activity. The mother and one sister of the patient were also carriers of this allelic variant.


CONCLUSIONS
Genotyping the allelic variants of the TPMT gene is a useful method to identify patients at moderate or high risk of myelosuppression after administration of azathioprine.
Corominas
H
H
Medicina Interna Hospital de la Santa Creu i Sant Pau. Barcelona.
Domènech
M
M
González-Juan
D
D
González-Suárez
B
B
Díaz
C
C
Pujol
J
J
Vázquez
G
G
Baiget
M
M
D000328:Adult; D001379:Azathioprine / Q000009:adverse effects*; D003424:Crohn Disease / Q000188:drug therapy; D006801:Humans; D007166:Immunosuppressive Agents / Q000009:adverse effects*; D008297:Male; D008780:Methyltransferases / Q000235:genetics*; D011110:Polymorphism, Genetic; D012010:Red-Cell Aplasia, Pure / Q000139:chemically induced*
D007166:Immunosuppressive Agents; D008780:Methyltransferases; C022745:thiopurine methyltransferase; D001379:Azathioprine