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 product of the ataxia - telangiectasia gene ( ATM ) was identified by using an antiserum developed to a peptide corresponding to the deduced amino acid sequence .
### Output Text:
The product of the <span class="disease">ataxia - telangiectasia</span> gene ( ATM ) was identified by using an antiserum developed to a peptide corresponding to the deduced amino acid sequence . 