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Great progress has been made in genetic dissection of quantitative trait variation during the past two decades , but many studies still reveal only a small fraction of quantitative trait loci ( QTLs ) , and epistasis remains elusive .
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Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Anatomy 
Text: {0} 
Answer:
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