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: These results are significant not only in terms of their implications for furthering our understanding of galactosemia and GALT holoenzyme structure - function relationships but also because the system described may serve as a model for similar studies of other complexes composed of multiple subunits . .
### Output Text:
These results are significant not only in terms of their implications for furthering our understanding of <span class="disease">galactosemia</span> and GALT holoenzyme structure - function relationships but also because the system described may serve as a model for similar studies of other complexes composed of multiple subunits . . 