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: In the haplotype - wise analysis , we detected an association between two markers ( rs6693503 and rs1805054 ) and three markers ( rs6693503 , rs1805054 and rs4912138 ) in HTR6 and METH - induced psychosis patients , respectively .
### Output Text:
In the haplotype - wise analysis , we detected an association between two markers ( rs6693503 and rs1805054 ) and three markers ( rs6693503 , rs1805054 and rs4912138 ) in HTR6 and <span class="chemical">METH</span> - induced psychosis patients , respectively . 