CYSLTR1 and asthma: The many examples discussed include, the VNTR sequences located in the Sp1-binding motif within the promotor region of the ALOX5 gene that are associated with both LTM response, leukotriene burden and bronchoconstriction (Drazen et al., 1999a), and the 444A > C SNP polymorphism in the LTC4S gene that is associated with severe asthma, leukotriene burden and altered response to the CYSLTR1 LTMs (Sampson et al., 2000; Kadry et al., 2014; Kazani et al., 2014).