1292
The segregation distortion favoring the mutant RB1 allele does not seem to occur during spermatogenesis , and , thus , meiotic drive may result either from various mechanisms , including a fertilization advantage or a better mobility in sperm bearing a mutant RB1 gene , or from the existence of a defectively imprinted gene located on the human X chromosome .
 None
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: Disease 
Text: {0} 
 Entities:  
Answer:
 None