31.4: Current Research Directions

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Quantifying Trait Variation

Because the study of eQTLs is a study in the level of expression of a gene, the primary step towards conducting an informative study is picking traits that have varying levels of expression rather than binary expression. Examples of such quantitatively viable traits are body mass index (BMI) and height. In the late 1980’s and early 1990’s, the first studies of gene expression through genome-wide mapping studies were initiated by Damerval and de Vienne [8] [6]. However, their use of 2-D electrophoresis for protein separation was inefficient and not thoroughly reliable as it introduced a lot of noise and could not be systematically and quantitatively summarized. It was only in the early 2000s when the introduction of high-throughput array- based methods to measure mRNA incidence accelerated the successful use of this method, first highlighted in a study by Brem [10].

New Applications

There are two directions that eQTL studies are headed. First, there is a rush to use whole genome eQTL analysis to validate associations among variances in the human population such as differences in gene expression among ethnic groups, as the statistical power for being able to do so is beginning to reach the threshold of significance. A second direction of research seeks to dislocate genetic associations with varying phenotypes and and population differences based on a non-genetic basis. These non-genetic factors include environment, cell line preparation, and batch effects.