Purpose of review: Expression quantitative trait loci (eQTL) mapping studies are the next most important step in genomics to identify susceptibility genes and molecular pathways involved in human diseases following the completion of genome-wide association studies (GWAS). This article reviews the emerging concepts in genetics of gene expression and the empirical value of eQTL mapping to refine GWAS asthma susceptibility loci.
Recent findings: eQTL mapping studies were paramount to reveal the cis and trans control of gene expression, the cell type and tissue specificity of eQTLs, and the pleiotropic nature of eQTL single nucleotide polymorphisms. A small number of eQTL studies were recently performed in tissues and cell types that are relevant for asthma and are used to interpret the biology underpinning GWAS loci including the most robust asthma susceptibility locus on 17q21.
Summary: The full potential of eQTL mapping studies is just starting to be revealed. Imminent progress is expected owing to the accelerating advances in sequencing technologies to map genetic variants and transcriptomes as well as the development of bioinformatics and computational algorithms to exploit integrative genomic approaches. A short-term challenge in the field of asthma is the creation of well powered eQTL datasets testing gene expression and other molecular phenotypes in disease-relevant tissues.