1646
These findings are thought to provide evidence against the concept that the gene for ankylosing spondylitis is not B27 but a closely linked gene and favour the occurrence of an environmental event affecting approximately one - fifth of B27 positive males to result in disease . .
 Disease: ankylosing spondylitis
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: ankylosing spondylitis 
Answer:
 Disease: ankylosing spondylitis