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: Identification and chromosomal localization of Atm , the mouse homolog of the ataxia - telangiectasia gene .
### Output Text:
Identification and chromosomal localization of Atm , the mouse homolog of the <span class="disease">ataxia - telangiectasia</span> gene . 