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: Strikingly , mice carrying multiple copies on a wild - type background show specific developmental abnormalities of the eye , but not of other tissues expressing the gene .
### Output Text:
Strikingly , mice carrying multiple copies on a wild - type background show specific <span class="disease">developmental abnormalities of the eye</span> , but not of other tissues expressing the gene . 