TLR9 and allergic bronchopulmonary aspergillosis: The structural gene CFTR has been previously associated with ABPA [11], and small genetic association studies (involving ≤38 patients) have identified associations between ABPA and SNPs in the immune genes IL4R, IL10, TLR9, SFTPA2 and HLA (HLA-DR) [12–16], however, these results do not explain all cases of ABPA, and the immune mechanisms that underlie ABPA remain unclear.