7744
More recently , however , Paul Glynn and colleagues showed that whereas conventional knockout of the NTE gene was embryonic lethal , conditional knockout of central nervous system NTE produced neurodegeneration , suggesting to these authors that the absence of NTE rather than its presence in some altered form caused disease .
 None
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 None