diff --git a/client/src/components/geneExpression/gene.js b/client/src/components/geneExpression/gene.js
index 10706f47..da09909e 100644
--- a/client/src/components/geneExpression/gene.js
+++ b/client/src/components/geneExpression/gene.js
@@ -106,7 +106,9 @@ class Gene extends React.Component {
                   top: -1,
                 }}
               />
-              <Truncate tooltipAddendum={`: ${geneDescription}`}>
+              <Truncate
+                tooltipAddendum={geneDescription && `: ${geneDescription}`}
+              >
                 <span
                   style={{
                     width: globals.leftSidebarWidth - genesetNameLengthVisible,