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   |  | Genes must be polymorphic
   to generate downstream genetic effects (as opposed to downstream molecular
   effects). Hars2 meets this condition because we have already mapped a
   functional polymorphism in the gene. We can therefore posit that Hars2 is a
   QT gene. What transcripts are downstream? App is one obvious
   candidate, but there are many more. 
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   |  | 
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   |  | The are several ways to
   look for downstream targets. The best and most obvious is to look up all
   transcripts that have high correlations with Hars2 itself. You should know
   how to do this. An alternative method is shown here for teaching purpose and
   to show you what to do if your gene of interest is not in our database. You
   need to know: 
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   |  | 
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   |  | 1. Where your gene is located. You need this information
   to find a surrogate marker; a marker that is located very close to your gene
   of interest. 
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   |  | 2. That your gene is
   polymorphic between C57BL/6J and DBA/2J. 
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   |  | 
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   |  | LetÕs look at the
   correlation of Hars2 with BXD genotypes as shown in the slide above to
   illustrate how to use markers as surrogate traits. 
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   |  | Go to the Trait Date and
   Editing window one more time. We want the data for Hars2 this time, not App.
   You should be able to show that Hars2 has a high  correlation with D2Mit423 as shown in the slide above. 
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   |  | 
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   |  | By clicking on the symbol
   D2Mit423 in the Correlation window, you will generate a new Trait Data
   window shown on the next slide. 
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