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: Molecular bases of combined subtotal deficiencies of C6 and C7 : their effects in combination with other C6 and C7 deficiencies .
### Output Text:
Molecular bases of <span class="disease">combined subtotal deficiencies of C6 and C7</span> : their effects in combination with other <span class="disease">C6 and C7 deficiencies</span> . 