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: We have developed a multiplex heteroduplex analysis that is designed to analyze one - quarter of the coding sequence in a single - step screening procedure and that will detect approximately 50 % of all BRCA1 mutations so far reported in breast / ovarian cancer families .
### Output Text:
We have developed a multiplex heteroduplex analysis that is designed to analyze one - quarter of the coding sequence in a single - step screening procedure and that will detect approximately 50 % of all BRCA1 mutations so far reported in <span class="disease">breast / ovarian cancer</span> families . 