Skip to main content
Biology LibreTexts

31.5: What Have We Learned?

  • Page ID
    41234
  • \( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \) \( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} \)\(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\) \(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\)\(\newcommand{\AA}{\unicode[.8,0]{x212B}}\)

    In summary, most causal variation for complex polygenic diseases that we have discovered so far is noncod- ing. Moreover, phenotypic differences between species are not well explained by coding variation, while gene expression is highly heritable between generations. Thus, it is proposed that genetic control of expression levels are a crucial factor in determining phenotypic variance.

    eQTLs are SNP variant loci that are correlated with gene expression levels. They come in one of two forms. Cis-eQTLs are sites whose loci map to near the affected genes, are relatively easy to detect due to their proximity, and generally have clear mechanisms of action. Trans-eQTLs map to distance areas of the genome, are more dicult to detect, and their mechanisms are not as direct.

    eQTL studies combine a whole-genome approach similar to GWAS with a expression assay, either microarray or RNA-seq. Expression levels of each gene are correlated by linear regression with genotypes after using PCA to extract confounding factors. Determining the optimal parameters for MAF, search radius, and confounder normalization is an open research question. Applications of eQTLs include the identification of disease-associated variants as well as variants associated with population subspecies and the genetic and environmental variance that gives rise to complex traits,


    31.5: What Have We Learned? is shared under a not declared license and was authored, remixed, and/or curated by LibreTexts.

    • Was this article helpful?