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Modern tactics such as genome - wide association studies ( GWAS ) and deep sequencing are fundamentally different from the pharmacology - guided approaches used previously , in which knowledge of small molecule ligands acting at their cellular targets was the primary discovery engine .
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Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
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