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: 2 kb and contain the intragenic microsatellite markers D17S1323 , D17S1322 , and D17S855 , which localize to introns 12 , 19 , and 20 , respectively .
### Output Text:
2 kb and contain the intragenic microsatellite markers D17S1323 , D17S1322 , and D17S855 , which localize to introns 12 , 19 , and 20 , respectively . 