What is the predictive value of HLA-B*5701 for abacavir hypersensitivity?

Updated: Dec 07, 2018
  • Author: Ali Torkamani, PhD; Chief Editor: Karl S Roth, MD  more...
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In immunologically confirmed hypersensitivity, HLA-B*5701 genotyping is associated with a negative predictive value of nearly 100% and a positive predictive value of approximately 50%. [7] That is, patients without the allele are highly unlikely to develop an immunologic hypersensitivity to abacavir, but only about half of those with the allele will develop such a reaction.

The genotype results are reported as either positive or negative. Only one copy of the HLA-B*5701 allele is required for a positive result. Therefore, the positive result can be heterozygous (1 copy of the allele) or homozygous (2 copies of allele). Although a negative result indicates that the patient does not carry the HLA-B*5701 allele, it does not entirely rule out the possibility of a patient developing abacavir hypersensitivity. [8]  In a study of 372 HLA-B*5701 patients, there was a 0.5% incidence of suspected avacavir hypersensitivity reaction. [6]  

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