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: Since the isolation of BRCA1 last year , > 65 distinct mutations scattered throughout the coding region have been detected , making analysis of the gene time consuming and technically challenging .
### Output Text:
Since the isolation of BRCA1 last year , > 65 distinct mutations scattered throughout the coding region have been detected , making analysis of the gene time consuming and technically challenging . 