Gene variation explains abacavir hypersensitivity
Researchers have identified a genetic variation associated with hypersensitivity to abacavir (Ziagen).
They say that 5 to 9 per cent of HIV-infected patients taking abacavir become
hypersensitive within a month. Symptoms include fever, rashes, gastrointestinal
upset and profound lethargy. The syndrome has proved fatal in rare cases.
The researchers studied the genotypes of 248 HIV patients treated with abacavir,
of whom 18 developed a severe reaction to the drug. Seventeen of these hypersensitive
patients had similar variations in the genes HLA-B*5701 and Hsp70-Hom, which
are near each other on chromosome 6. This genetic combination was present in
only one of the 230 patients who tolerated the drug well.
In the trial cohort, the authors predict that only 14 patients would have needed
genetic screening to prevent one case of hypersensitivity. However, they warn
that their findings might not apply to non-Caucasian patients. They say that
prospective genetic testing for abacavir hypersensitivity is likely to be highly
predictive. In populations of European descent, in which one of the variations
is relatively common, testing is also likely to be cost-effective (Proceedings of the National Academy of Sciences 2004;101:4180). |
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