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: Whereas heterozygotes suffer from iris hypoplasia , homozygous mice lack eyes and nasal cavities and exhibit brain abnormalities .
### Output Text:
Whereas heterozygotes suffer from <span class="disease">iris hypoplasia</span> , homozygous mice lack eyes and nasal cavities and exhibit <span class="disease">brain abnormalities</span> . 