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: Cumulative mutation data have revealed that WASP genotypes are also highly variable among WAS patients , but the relationship of phenotype with genotype in this disease remains unclear .
### Output Text:
Cumulative mutation data have revealed that WASP genotypes are also highly variable among <span class="disease">WAS</span> patients , but the relationship of phenotype with genotype in this disease remains unclear . 