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 protein truncation test ( PTT ) was used on RT - PCR products , SSCP on genomic PCR amplifications , and chemical cleavage of mismatch on both RT - PCR and genomic amplifications .
### Output Text:
The protein truncation test ( PTT ) was used on RT - PCR products , SSCP on genomic PCR amplifications , and chemical cleavage of mismatch on both RT - PCR and genomic amplifications . 