Update 03_DGE_QC_analysis.md

typo

lessons/03_DGE_QC_analysis.md

@@ -118,7 +118,7 @@ Similar to PCA, hierarchical clustering is another, complementary, method for id
 
 The hierarchical tree along the axes indicates which samples are more similar to each other, i.e. cluster together. The color blocks at the top indicate substructure in the data, and you would expect to see your replicates cluster together as a block for each sample group. Our expectation would be that the samples cluster together similar to the groupings we've observed in the PCA plot. 
 
-**In the plot below, we would be quite concerned about 'Wt_3' and 'KO_3' samples not clustering with the other replicates. We would want to explore the PCA to see if we see the same clustering of samples.**
+**In the plot below, we would be quite concerned about 'Wt_3' and 'KD_3' samples not clustering with the other replicates. We would want to explore the PCA to see if we see the same clustering of samples.**
 
 <p align="center">
 <img src="../img/heatmap_example.png" width="500">