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: FISH with a SNRPN probe will permit analysis of PWS patients with limited deletions not detectable with other probes . .
### Output Text:
FISH with a SNRPN probe will permit analysis of <span class="disease">PWS</span> patients with limited deletions not detectable with other probes . . 