- OTU Domain Containing Protein 3 (OTUD3)
- OTU Domain Containing Protein 4 (OTUD4)
- OTU Domain Containing Protein 5 (OTUD5)
- OTU Domain Containing Protein 6B (OTUD6B)
- OTU Domain Containing Protein 6A (OTUD6A)
- Odd Skipped Related Protein 2 (OSR2)
- Odd Skipped Related Protein 1 (OSR1)
- Origin Recognition Complex Subunit 6 Like Protein (ORC6L)
- Origin Recognition Complex Subunit 1 Like Protein (ORC1L)
- Origin Recognition Complex Subunit 2 Like Protein (ORC2L)
- Origin Recognition Complex Subunit 3 Like Protein (ORC3L)
- Origin Recognition Complex Subunit 4 Like Protein (ORC4L)
- Origin Recognition Complex Subunit 5 Like Protein (ORC5L)
- Olfactory Receptor 1D2 (OR1D2)
- Olfactory Receptor 1F1 (OR1F1)
