Following the completion of genome-wide association studies, expression quantitative trait loci (eQTL) mapping studies are the most crucial step in genomics for identifying susceptibility genes and molecular pathways implicated in human disorders (GWAS). In this article, researchers discuss the new concepts in gene expression genetics as well as the empirical relevance of eQTL mapping in refining GWAS asthma susceptibility regions. The importance of eQTL mapping studies in revealing the cis and trans regulation of gene expression, the cell type and tissue specificity of eQTLs, and the pleiotropic character of eQTL single nucleotide polymorphisms cannot be overstated. A modest number of eQTL studies in asthma-relevant tissues and cell types have recently been conducted and are being utilized to evaluate the biology behind GWAS loci, including the most strong asthma susceptibility locus on 17q21. 

The full potential of eQTL mapping investigations is only now becoming realized. Immediate improvement is envisaged as sequencing technology for mapping genetic variations and transcriptomes expand, as well as the development of bioinformatics and computer algorithms to leverage integrative genomic techniques. The generation of well-powered eQTL datasets evaluating gene expression and other molecular characteristics in disease-relevant tissues is a short-term challenge in the area of asthma.