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In the DNAs of all Ph1 - positive chronic myelocytic leukemia patients studied to date , a breakpoint on chromosome 22 ( the Ph1 chromosome ) can be demonstrated with a probe from the bcr ( breakpoint cluster region ) .
 bcr, breakpoint cluster region
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: GENE 
Text: {0} 
Answer:
 bcr, breakpoint cluster region