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: Although this microsatellite instability has been attributed to mutations in four DNA mismatch repair genes in hereditary nonpolyposis colorectal cancer ( HNPCC ) kindreds , many sporadic tumours exhibit instability but no detectable mutations in these genes .
### Output Text:
Although this <span class="disease">microsatellite instability</span> has been attributed to mutations in four DNA mismatch repair genes in <span class="disease">hereditary nonpolyposis colorectal cancer</span> ( <span class="disease">HNPCC</span> ) kindreds , many <span class="disease">sporadic tumours</span> exhibit instability but no detectable mutations in these genes . 