Susceptibility genes for lung diseases in the major histocompatibility complex revealed by lung expression quantitative trait loci analysis

The major histocompatibility complex (MHC) has been linked with hundreds of diseases [1]. The MHC is one of the most complex regions of the human genome, because of the high gene density, extended linkage disequilibrium (LD) and sequence diversity [2]. Recent genome-wide association studies (GWAS) have identified polymorphisms located in the MHC that are associated with lung diseases and related traits: asthma, cystic fibrosis, idiopathic interstitial pneumonia, lung cancer and lung function. However, due to the limitations of GWAS and tissue-specific characteristics of gene expression [3], the causal genes and genetic mechanisms mediating the heritable risk within this locus remain to be found.