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 effect of altered expression levels of DMPK , which is ubiquitously expressed in all muscle cell lineages during development , was examined by disrupting the endogenous Dmpk gene and overexpressing a normal human DMPK transgene in mice .
### Output Text:
The effect of altered expression levels of DMPK , which is ubiquitously expressed in all muscle cell lineages during development , was examined by disrupting the endogenous Dmpk gene and overexpressing a normal human DMPK transgene in mice . 