In the sentence extracted from biomedical literature, identify all the disease entities. The required answer format is the same sentence with HTML <span> tags to mark up specific entities. 
### Entity Markup Guides:
Use <span class="disease"> to denote a disease.

### Input Text: The 5 ' end of the BRCA1 gene lies within a duplicated region of human chromosome 17q21 .
### Output Text:
The 5 ' end of the BRCA1 gene lies within a duplicated region of human chromosome 17q21 . 