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 most common variant of GALT , the Duarte variant , occurs as two types , Duarte - 1 ( D - 1 ) and Duarte - 2 ( D - 2 ) , both of which carry the sequence change N314D .
### Output Text:
The most common variant of GALT , the Duarte variant , occurs as two types , Duarte - 1 ( D - 1 ) and Duarte - 2 ( D - 2 ) , both of which carry the sequence change N314D . 