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: ALD is due to mutation of a gene located in Xq28 that encodes a peroxisomal transporter protein of unknown function .
### Output Text:
<span class="disease">ALD</span> is due to mutation of a gene located in Xq28 that encodes a peroxisomal transporter protein of unknown function . 