Table 1. Polymorphic HERV-K loci in the human genome.

HERV-K	No. of differences between LTRs	Integration time (mya)*
11q22	4	0.81-2.3
12q14	4	0.81-2.3
109	3	0.61-1.8
1p31†	3	0.82-2.4‡
115	5	1.0-2.9§
108	6	1.2-3.5

mya, million years ago.

^*Calculations based on the average nucleotide substitution rate of HERV-K loci of 3.77 × 10^-9 ± 1.33

^†This element was not located in the blot but was found by PCR analysis to be polymorphic

^‡Estimated from an alignment of 715 bp, instead of the full-length 968, because of missing sequence data in the 5′ LTR

^§Integration time estimate taken from ref. 12