477
This idea is based partly on the phenotype of homozygous Krox20 ( Egr2 ) knockout mice , which display hypomyelination of the PNS and a block of Schwann cells at an early stage of differentiation .
 hypomyelination of the PNS
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Disease 
Text: {0} 
Answer:
 hypomyelination of the PNS