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In addition , it has been found that there is not only an increased incidence of ARM in patient with trisomy 21 ( Down ' s syndrome ) , but that 95 % of patients with trisomy 21 and ARM have imperforate anus without fistula , compared with only 5 % of all patients with ARM .
 anus, fistula
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Anatomy 
Text: {0} 
Answer:
 anus, fistula