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 nucleotide sequence obtained from the genomic regions adjacent to the exon boundaries enabled us to develop a set of primer pairs for PCR amplification of the complete coding region .
### Output Text:
The nucleotide sequence obtained from the genomic regions adjacent to the exon boundaries enabled us to develop a set of primer pairs for PCR amplification of the complete coding region . 