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: Such recurrent CpG mutations , including those found in RB1 , are likely the result of the deamination of 5 - methylcytosine within these CpGs .
### Output Text:
Such recurrent CpG mutations , including those found in RB1 , are likely the result of the deamination of 5 - methylcytosine within these CpGs . 