Table 2. Distribution of structure updates corresponding to assembly type.

Structure update class	No. of FL assemblies	No. of EST assemblies
Alters UTR annotations	8844 (8800)	4174 (3444)
Extends CDS structure, elongating protein	309 (309)	275 (274)
Alters internal gene structure	732 (732)	905 (853)
Provides alternate splicing isoform	529 (502)	701 (645)
Provides novel gene annotation	73 (73)	NA

The number of genes updated by the assemblies is shown in parentheses. The number of genes is less than the number of assemblies in cases where multiple isoforms of a single gene are updated by multiple assemblies (more common with FL assemblies) or where single isoforms are updated by multiple assemblies (more common with EST assemblies; see examples in Fig. 3f–h). Although the alignment assembly update classes are mutually exclusive, 1385 of the 14 247 updated genes fall into multiple categories.