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: To investigate the role of genomic sequences in instability , we produced transgenic mice containing a 45 - kb genomic segment with a 55 - CTG repeat cloned from a mildly affected patient .
### Output Text:
To investigate the role of genomic sequences in instability , we produced transgenic mice containing a 45 - kb genomic segment with a 55 - CTG repeat cloned from a mildly affected patient . 