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: Mutations in the WT1 gene were anticipated to explain the genetic basis of the childhood kidney cancer , Wilms tumour ( WT ) .
### Output Text:
Mutations in the WT1 gene were anticipated to explain the genetic basis of the childhood <span class="disease">kidney cancer</span> , <span class="disease">Wilms tumour</span> ( <span class="disease">WT</span> ) . 