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: Northern analysis of sf tissue samples indicated the presence of WASP mRNA in liver and skin , presumably as a consequence of lymphocytic infiltration , but non abnormalities in the amount or size of mRNA present .
### Output Text:
Northern analysis of sf tissue samples indicated the presence of WASP mRNA in liver and skin , presumably as a consequence of lymphocytic infiltration , but non abnormalities in the amount or size of mRNA present . 