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: The variable penetrance of BRCA1 suggests that other genetic and non - genetic factors play a role in tumourigenesis in these individuals .
### Output Text:
The variable penetrance of BRCA1 suggests that other genetic and non - genetic factors play a role in tumourigenesis in these individuals . 