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Two overlapping clones contained the complete Adh - 2 gene composed of nine exons in a 12 - kb region , with the placement of introns matching that observed in other mammalian ADH genes .
 Adh - 2 gene, mammalian ADH genes
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: GENE 
Text: {0} 
Answer:
 Adh - 2 gene, mammalian ADH genes