Table 1.
Intronless, monomorphic, and polymorphic genes in different age classes of human genes.
| Number of Genes | Evolutionary Age of Genes |
||||||
| Gene Type | Cellular | Eukaryota | Metazoa | Chordata | Mammalia | Primates | |
| Polymorphic | 11,082 | 3,111 (0.609) | 3,310 (0.617) | 2,474 (0.560) | 1,623 (0.481) | 505 (0.389) | 59 (0.249) |
| Monomorphic | 7,651 | 1,903 (0.372) | 1,874 (0.349) | 1,745 (0.395) | 1,325 (0.393) | 645 (0.497) | 159 (0.671) |
| Intronless | 1,072 | 96 (0.019) | 184 (0.034) | 199 (0.045) | 426 (0.126) | 148 (0.114) | 19 (0.080) |
| Mono/Poly | 0.883 | 0.826 | 1.022 | 1.185 | 1.826 | 4.2 | |
| Intronless/Poly | 0.317 | 0.541 | 0.834 | 2.719 | 3 | 3.4 | |
Protein CDSs of 22,849 human genes were classified according to the ancestral taxa where the proteins first appeared. Ancestral homologues were identified in RefSeq sequences from organisms of different taxonomic levels by BLASTP search with an expectation cutoff value of 10−6 using a procedure described in Supplementary Material online. Frequencies of gene types in evolutionary age classes are shown in parentheses. Mono/poly and intronless/poly ratios were normalized taking into account numbers of genes in the groups.