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: Cloning of the homogentisate 1 , 2 - dioxygenase gene , the key enzyme of alkaptonuria in mouse .
### Output Text:
Cloning of the homogentisate 1 , 2 - dioxygenase gene , the key enzyme of <span class="disease">alkaptonuria</span> in mouse . 