15945
By introducing the SMN ( RT ) transgene onto the background of a severe mouse model of SMA ( SMN2 ( + / + ) ; Smn ( - / - ) ) , disease severity was significantly decreased based upon a battery of phenotypic parameters , including MN pathology and a significant extension in survival .
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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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