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Evaluation by postal questionnaires , and pelvic radiography of 78 HL - A 27W - positive blood donors selected from a group of apparently healthy subjects revealed 14 who satisfied the criteria for definite ankylosing spondylitis .
 ankylosing spondylitis
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Disease 
Text: {0} 
Answer:
 ankylosing spondylitis