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 mutation of case 1 was a homozygous T to A transversion at nucleotide 2250 , the third nucleotide of the codon TGT for Cys728 , leading to a stop codon TGA ( C728X ) .
### Output Text:
The mutation of case 1 was a homozygous T to A transversion at nucleotide 2250 , the third nucleotide of the codon TGT for Cys728 , leading to a stop codon TGA ( C728X ) . 