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Substitution of the DR1 beta chain with H - 2E beta k led to a dramatic loss of recognition ; alpha chain substitution had a less marked effect .
 DR1 beta chain, H - 2E beta k
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: GENE 
Text: {0} 
Answer:
 DR1 beta chain, H - 2E beta k