In the sentence extracted from biomedical literature, identify all the chemical entities. The required answer format is the same sentence with HTML <span> tags to mark up specific entities. 
### Entity Markup Guides:
Use <span class="chemical"> to denote a chemical.

### Input Text: RESULTS : rs6693503 was associated with METH - induced psychosis patients in the allele / genotype - wise analysis .
### Output Text:
RESULTS : rs6693503 was associated with <span class="chemical">METH</span> - induced psychosis patients in the allele / genotype - wise analysis . 