Candidate gene and genome wide studies have localized genetic regions involved in the disease, such as the A1AR and CLCA1 genes (chromosome 1), IL-1RN and DPP10 (2q14), HLA-G and TNF-a (6p21), GPRA (7p14), FceRI and GSTP1 (11q13), NOS1, IFNG, STAT6, VDR, and other genes (12q13-26), PHF11 and flanking genes (13q14), AACT and PTGDR (14q), and ADAM33 (20p13).