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: Over 100 distinct disease - associated mutations have been identified in the breast - ovarian cancer susceptibility gene BRCA1 .
### Output Text:
Over 100 distinct disease - associated mutations have been identified in the <span class="disease">breast - ovarian cancer</span> susceptibility gene BRCA1 . 