To achieve large sample sizes in humans, tissues must be accessible, and an attractive choice is peripheral venous blood, while most but not all20,29 human blood-derived eQTL studies have used LCLs. However, gene expression differs between LCLs and peripheral blood30 and LCLs can be influenced by factors such as EBV copy number and growth rates.31 A MuTHER LCL study of expression in female twins found a large impact of common “environment” shared by twins: 32% of transcripts showed common environmental effects >30%, compared to 2% in adipose and 8% in skin.8 The authors attributed the dramatic effect to correlated sample handling rather than environmental exposures shared by co-twins, suggesting possible biases with LCLs.
