16928
The different genotype frequencies of MPO , including - 1228G / A , - 585T / C , - 463G / A , and - 163C / T , and the three haplotypes with higher frequencies , including - 163C - 463G - 585T - 1228G - 1276T , - 163C - 463G - 585T - 1228G - 1276C , and - 163C - 463G - 585T - 1228A - 1276T , were significantly associated with fluorosis .
 None
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 None