2223
In analogy to apoE2 k . i . mice , a lower OPG / RANKL ratio was observed in the serum of epsilon 2 / epsilon 2 carriers as compared to epsilon 3 / epsilon 3 and epsilon 4 / epsilon 4 individuals ( p = 0 . 02 for epsilon 2 / epsilon 2 versus epsilon 4 / epsilon 4 ) .
 None
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
 Entities:  
Answer:
 None