diff --git a/client/src/components/geneExpression/gene.js b/client/src/components/geneExpression/gene.js
index 152c68b8..10706f47 100644
--- a/client/src/components/geneExpression/gene.js
+++ b/client/src/components/geneExpression/gene.js
@@ -59,6 +59,7 @@ class Gene extends React.Component {
   render() {
     const {
       gene,
+      geneDescription,
       isColorAccessor,
       isScatterplotXXaccessor,
       isScatterplotYYaccessor,
@@ -68,6 +69,7 @@ class Gene extends React.Component {
     } = this.props;
     const { geneIsExpanded } = this.state;
     const genesetNameLengthVisible = 310; /* this magic number determines how much of a long geneset name we see */
+
     return (
       <div>
         <div
@@ -104,7 +106,7 @@ class Gene extends React.Component {
                   top: -1,
                 }}
               />
-              <Truncate>
+              <Truncate tooltipAddendum={`: ${geneDescription}`}>
                 <span
                   style={{
                     width: globals.leftSidebarWidth - genesetNameLengthVisible,
diff --git a/client/src/components/geneExpression/geneSet.js b/client/src/components/geneExpression/geneSet.js
index c7b2e15c..aeb359ca 100644
--- a/client/src/components/geneExpression/geneSet.js
+++ b/client/src/components/geneExpression/geneSet.js
@@ -86,7 +86,13 @@ class GeneSet extends React.Component {
   };
 
   renderGenes() {
-    const { setName, setGenes, isDiffExp, diffExp } = this.props;
+    const {
+      setName,
+      setGenes,
+      setGenesWithDescriptions,
+      isDiffExp,
+      diffExp,
+    } = this.props;
 
     if (isDiffExp) {
       // [ [gene, logfoldchange, pval, pval_adj], ...]
@@ -108,7 +114,16 @@ class GeneSet extends React.Component {
 
     // otherwise...
     return setGenes.map((gene) => {
-      return <Gene key={gene} gene={gene} geneset={setName} />;
+      const { geneDescription } = setGenesWithDescriptions.get(gene);
+
+      return (
+        <Gene
+          key={gene}
+          gene={gene}
+          geneDescription={geneDescription}
+          geneset={setName}
+        />
+      );
     });
   }
 
diff --git a/client/src/components/geneExpression/index.js b/client/src/components/geneExpression/index.js
index eca8891c..59d7f400 100644
--- a/client/src/components/geneExpression/index.js
+++ b/client/src/components/geneExpression/index.js
@@ -16,11 +16,12 @@ class GeneExpression extends React.Component {
     const sets = [];
     const { genesets } = this.props;
 
-    for (const [name, genes] of genesets) {
+    for (const [name, geneset] of genesets) {
       sets.push(
         <GeneSet
           key={name}
-          setGenes={Array.from(genes.genes.keys())}
+          setGenes={Array.from(geneset.genes.keys())}
+          setGenesWithDescriptions={geneset.genes}
           setName={name}
         />
       );
diff --git a/client/src/components/util/truncate.js b/client/src/components/util/truncate.js
index 80c9eaf0..85aaf26e 100644
--- a/client/src/components/util/truncate.js
+++ b/client/src/components/util/truncate.js
@@ -33,7 +33,7 @@ const SECOND_HALF_INNER_STYLE = {
 };
 
 export default (props) => {
-  const { children } = props;
+  const { children, tooltipAddendum = "" } = props;
   // Truncate only support a single child with a text child
 
   if (
@@ -87,7 +87,7 @@ export default (props) => {
   );
   return (
     <Tooltip2
-      content={originalString}
+      content={`${originalString}${tooltipAddendum}`}
       hoverOpenDelay={tooltipHoverOpenDelayQuick}
       targetProps={{ style: children.props.style }}
     >