The invention concerns the genomic sequence of the FLAP gene. The invention also concerns biallelic markers of a FLAP gene and the association established between these markers and diseases involving the leukotriene pathway such as asthma. The invention provides means to determine the predisposition of individuals to diseases involving the leukotriene pathway as well as means for the diagnosis of such diseases and for the prognosis/detection of an eventual treatment response to agents acting on the leukotriene pathway.