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 Wiskott - Aldrich syndrome ( WAS ) , an X - linked immunodeficiency disease caused by mutation in the recently isolated gene encoding WAS protein ( WASP ) , is known to be associated with extensive clinical heterogeneity .
### Output Text:
The <span class="disease">Wiskott - Aldrich syndrome</span> ( <span class="disease">WAS</span> ) , an <span class="disease">X - linked immunodeficiency disease</span> caused by mutation in the recently isolated gene encoding <span class="disease">WAS</span> protein ( WASP ) , is known to be associated with extensive clinical heterogeneity . 