Genetic mechanism of aspirin-induced urticaria/angioedema

Purpose of review Aspirin-induced urticaria/angioedema is a major aspirin-related hypersensitivity often associated with aspirin-intolerant asthma. Genetic studies on aspirin-intolerant asthma have shown chronic overproduction of cysteinyl leukotrienes. The genetic analysis of aspirin-induced urticaria/angioedema is limited, however. Recent findings A recent study on HLA genotypes has suggested that the HLA alleles DRB1*1302 and DQB1*0609 may be genetic markers for aspirin-induced urticaria/angioedema. A polymorphism study that examined nine single-nucleotide polymorphisms of five leukotriene-related genes [ALOX5 (encoding 5-lipoxgenase), ALOX5AP (5-lipoxygenase-activating protein), PTGS2 (cyclooxygenase 2), LTC4S (leukotriene C4 synthase), and CYSLTR1 (cysteinyl leukotriene receptor 1)] found that promoter polymorphisms of ALOX5 (-1708A>G) and CYSLTR1 (-634C>T) were significantly different between aspirin-intolerant asthma and aspirin-induced urticaria/angioedema, suggesting different contributions to the lipoxygenase pathway. A second polymorphism study, conducted on histamine-related genes, did not find any significant associations wit aspirin-induced urticaria/angioedema for the genes HNMT (encoding histamine N-methyltransferase), HRH1 or HRH2 (encoding histamine receptor type 1 and 2 respectively), or the gene encoding high-affinity IgE receptor 1 beta (Fc epsilon RI beta); however, the Fc epsilon RI alpha gene promoter polymorphism was significantly associated with aspirin-induced urticaria/angioedema. This finding has been supported by in vitro functional studies. Summary The HLA alleles DRB1*1302 and DQB1*0609 and the ALOX5 and Fc epsilon RI alpha promoter polymorphisms, may contribute to the pathogenesis of aspirin-induced urticaria/angioedema. Further investigation to identify candidate genetic markers would help to elucidate the pathogenic mechanism of this condition.