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: A second , recently identified familial breast cancer gene , BRCA2 ( refs 5 - 8 ) , accounts for a proportion of breast cancer roughly equal to BRCA1 .
### Output Text:
A second , recently identified <span class="disease">familial breast cancer</span> gene , BRCA2 ( refs 5 - 8 ) , accounts for a proportion of <span class="disease">breast cancer</span> roughly equal to BRCA1 . 