Transcriptome-wide association study: Opportunity and challenges for cancer studies

Genome-wide association studies (GWAS) have uncovered thousands of single nucleotide polymorphism (SNP) loci that are associated with complex traits. However, the majority of GWAS discoveries are located in non-coding regions and the biological mechanisms behind these associations are not well understood. Transcriptome-wide association studies (TWAS) have gained popularity in recent years by generating biological interpretable discoveries and facilitating the identification of novel associations that have been missed by GWAS. TWAS has identified more than hundreds of susceptibility genes for many complex diseases and traits, including cancers. Here, in this review, we first summarize TWAS methods, then discuss the opportunities for cancer studies and finally review current challenges and future directions for this method