- fgt
gene class name discontinued since WS288
- secr
Retired gene class, see the remarks for additional context.
- sqr
Retired gene class, see the remarks for additional context.
- isl
Retired gene class, see the remarks for additional context.
- sncr
NOTICE: This gene class has been retired in 2023 (since WS291). Sm associated NonCoding Rnas (RNAs)
- srab
Serpentine Receptor, class AB (class A-like)
- srbc
Serpentine Receptor, class BC (class B-like)
- abcf
ABC transporter, class F
- srn
Serpentine Receptor, class N