Number of Different HERV-W Elements in the Human Genome
| Group | Number | Complete | 5′ truncation[i] | 3′ truncation[i] | 5′3′ truncation[i] |
| poly(A) | 176 | 46 | 107 | 23 | 0 |
| retro (internal sequence–containing) | 77 | 29 | 15 | 24 | 9 |
| retro (soloLTR) | 343 | 306 | 20 | 13 | 4 |
| undef | 58 | 0 | 0 | 0 | 58 |
[i] Truncations were defined according to alignments with a particular consensus sequence for each group. The terminal gap was counted if the start or the end of the element was more distant than 20 bp from the consensus termini.