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 current study was aimed at finding the molecular basis of Canavan disease in 25 independent patients of non - Jewish background .
### Output Text:
The current study was aimed at finding the molecular basis of <span class="disease">Canavan disease</span> in 25 independent patients of non - Jewish background . 