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: To address this issue we characterized WASP mutations in 24 unrelated WAS patients , including 18 boys with severe classical WAS and 6 boys expressing mild forms of the disease , and then examined the degree of correlation of these as well as all previously published WASP mutations with disease severity .
### Output Text:
To address this issue we characterized WASP mutations in 24 unrelated <span class="disease">WAS</span> patients , including 18 boys with severe classical <span class="disease">WAS</span> and 6 boys expressing mild forms of the disease , and then examined the degree of correlation of these as well as all previously published WASP mutations with disease severity . 