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: Exon PCR and sequencing revealed a heterozygous point mutation at the 3 splice acceptor site of intron 1 in one Irish family .
### Output Text:
Exon PCR and sequencing revealed a heterozygous point mutation at the 3 splice acceptor site of intron 1 in one Irish family . 