Add a new heat map view to show gene co-expression

[amkwong]

Goal

When a user searches for a gene, we want to add a new view which will:

• Show other interesting related genes in all tissues, and the degree to which they are similar to the searched gene
• Provide an easy way to view the new interesting genes and tissues

Rationale

• Currently, when a user searches for a gene, we look for the tissue which has the most significant P-value and show them a region plot for that particular gene x tissue combination
• When you are in region view, it is difficult if not impossible to figure out what other genes or tissues will also have meaningful signals, making it difficult for the user to discover connections between genes and tissues by simply browsing

Implementation

• To address the points above, we should add and change a few features:

1. When a user searches for a gene, ins addition to redirecting to a gene x tissue region plot, we should also show a heat map-like display of some number of top co-expressed genes (e.g. top 10)
2. The heat map will be a new visualization element: the x-axis will be the different tissues, while the y-axis will be the top co-expressed genes, along with the anchor gene at the top. It will look like this page, except with the following differences:

• no dendrograms
• indications for what is currently being shown in the region view plot (anchor tissue x gene, and any additional tissues and/or genes)
• colors will stand for R^2 with the anchor tissue instead of TPM: https://gtexportal.org/home/multiGeneQueryPage/APOB,APOE,LDLR

3. To make this lookup more efficient, we want to pre-calculate all gene-gene correlations in all tissues, so that when the user searches for a gene, we can simply retrieve the 10 genes with the highest correlations (in any tissue) to display
4. From this heat map view, the user should have the option to do any of the following:

• Easily see the current anchor gene and tissue, plus any other tissues or genes which are currently displayed
• Choose a new anchor gene and/or tissue, which updates the current page
• Choose genes and/or tissues to add to or subtract from region view

Essentially, this heat map will serve as both a suggestion mechanism and a control element for the region view page. This will make adding tissues and genes easier, and is also a more intuitive way to summarize the current region view.