Manually annotated GENCODE gene features are subdivided into categories on the basis of their functional potential and the source of the evidence supporting their annotation. Annotated gene models are predominantly supported by transcriptional and/or protein evidence. Once the structure of a model has been established, it is classified into one of three broad locus level biotypes: protein-coding gene, long noncoding RNA (lncRNA) gene, or pseudogene. In addition, more detailed biotypes are associated with transcripts to attempt to assign a functionality, for example, protein-coding or subject to nonsense mediated decay (NMD) (see landscape Supplemental Tables).
