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: Genetic analysis was undertaken to establish linkage between the breast or ovarian cancer cases and markers on chromosomes 17q ( BRCA1 ) and 13q ( BRCA2 ) .
### Output Text:
Genetic analysis was undertaken to establish linkage between the <span class="disease">breast or ovarian cancer</span> cases and markers on chromosomes 17q ( BRCA1 ) and 13q ( BRCA2 ) . 