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 previously undescribed mutation within the tetramerisation domain of TP53 in a family with Li - Fraumeni syndrome .
### Output Text:
A previously undescribed mutation within the tetramerisation domain of TP53 in a family with <span class="disease">Li - Fraumeni syndrome</span> . 