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1: Arthritis Rheum. 1997 Oct;40(10):1896-8.Links
Comment in:
Arthritis Rheum. 1998 Oct;41(10):1899-900.

Azathioprine-induced severe pancytopenia due to a homozygous two-point mutation of the thiopurine methyltransferase gene in a patient with juvenile HLA-B27-associated spondylarthritis.

Leipold G, Schütz E, Haas JP, Oellerich M.

Children's Hospital of University Erlangen-Nürnberg, Erlangen, Germany.

Severe pancytopenia due to azathioprine (AZA) toxicity in patients with autoimmune diseases is not uncommon. We describe a 14-year-old girl with HLA-B27+ spondylarthritis who was treated with AZA 3 mg/kg/day and who suddenly developed severe pancytopenia in the seventh week of treatment. Analysis of the catabolic pathway of AZA revealed a homozygous deficiency of thiopurine methyltransferase (TPMT) on the basis of a combined 2-point mutation at nucleotide positions 460 and 719 in the gene for TPMT, causing a toxic level of the metabolic active 6-thioguanine nucleotides (6-TGN) (2,394 pmoles/8 x 10(8) red blood cells). The patient was transfusion dependent and finally recovered 8 weeks after the development of the pancytopenia. At that time, 6-TGN had already returned to normal therapeutic levels. Family studies revealed another homozygous deficiency in the mother, while the other family members were heterozygous.

PMID: 9336428 [PubMed - indexed for MEDLINE]

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  • Mercaptopurine (Purinethol® )

    Your doctor has ordered the drug mercaptopurine to help treat your illness. The drug is taken by mouth in tablet form.

  • Azathioprine (Azasan® , Imuran® )

    Azathioprine is used with other medications to prevent rejection of kidney transplants. It is also used to treat severe rheumatoid arthritis (a condition in which the body attacks its own joints, causing pain and swellin...

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