Initiating allopurinol therapy: do we need to know HLA status?

January 01, 0001

Initiating allopurinol therapy: do we need to know HLA status?

Allopurinol-induced hypersensitivity (AH) can rarely be manifest as Stevens Johnson Syndrome (SJS) or Toxic Epidermal Necrolysis (TEN) that have high mortality rates. Less serious, but still significant, skin and systemic hypersensitivity reactions form part of the AH spectrum. One hundred percent of Han Chinese with SJS/TEN due to allopurinol have been found to be at least heterozygous for HLA-B5801, the carriage rate for this allele in the Han Chinese population being about 15%. The association has been found to be weaker in Caucasians whose HLA-B5801 carriage rate is less than 6%. The researchers from Australia examined the relationship between the different skin hypersensitivity reactions to allopurinol and the HLA-B locus in Australian patients. They examined 23 patients referred with AH.

Five of six Australian SJS/TEN patients were heterozygous for HLA-B5801 and four were of South East Asian origin. Five AH patients without SJS/TEN were all Caucasian and only one of these was positive for HLA-B5801. Twelve patients with allopurinol-induced maculopapular exanthema were negative for HLA-B5801 including one South East Asian.

The researchers concluded: "Cases of AH manifesting as SJS/TENS in Australians are more likely to be in those of Asian heritage. The place of routine testing for HLA-B5801 prior to commencing allopurinol therapy requires further investigation. However, Han Chinese origin patients commencing allopurinol might be informed of the test and may elect to have it performed as there are alternative hypouricaemic medicines such as probenecid thereby reducing the risk of a catastrophic reaction to allopurinol."

A nasty reaction that can be prevented.

For the full abstract, click here.

Internal Medicine Journal published online 25 July 2011 © 2011 Royal Australasian College of Physicians
Initiating allopurinol therapy: do we need to know the patient's HLA status?. Ming-Han H Lee, Sophie L Stocker, Jacqueline Anderson et al. Correspondence to Richard Day: [email protected]

Category: M. Musculoskeletal. Keywords: allopurinol, HLA-B5801, hypersensitivity reaction, drug induced hypersensitivity reaction, DRESS, Steven-Johnson Syndrome, Toxic Epidermal Necrolysis, cohort study, journal watch.
Synopsis edited by Dr Stephen Wilkinson, Melbourne, Australia. Posted on Global Family Doctor 12 August 2011

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