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: 45 - kilobases ( kb ) exon 11 of the hereditary breast and ovarian cancer gene BRCA1 .
### Output Text:
45 - kilobases ( kb ) exon 11 of the <span class="disease">hereditary breast and ovarian cancer</span> gene BRCA1 . 