SEQUENCES FROM HIGHER PRIMATES ORTHOLOGOUS TO THE HUMAN XP YP TELOMERE JUNCTION REGION REVEAL GROSS REARRANGEMENTS AND HIGH-LEVELS OF DIVERGENCE/

A high level of sequence polymorphism combined with linkage disequilib rium has created a limited number of highly diverged haplotypes across the human Xp/Yp telomere junction region, To gain insight into the un usual genetic characteristics of this region, we have examined the ort hologous sequences in the common chimpanzee (Pan troglodytes), the gor illa (Gorilla gorilla) and the orang-utan (Pongo pygmaeus), Divergence from the human Xp/Yp sequence is higher (average 2.6-fold) than that observed at other loci, The position of the human Xp/Yp telomere is un ique, as additional sequences are present at this location in the othe r three species, These included an array of subterminal satellite in t he chimpanzee and, in the gorilla a small interstitial array of telome re-like repeats followed by sequences with strong homology to the huma n 18p subterminal region, In the orang-utan, two alleles with differen t structures were identified, These differ by the presence or absence of a short interspersed nuclear element (SINE) sequence just proximal to long arrays of telomere-like repeat sequences that probably represe nt the proximal end of the orang-utan Xp/Yp telomere, In addition, a h igh level of sequence divergence between the two orang-utan structures was identified, This divergence is similar to that observed between t he human Xp/Yp telomere-adjacent haplotypes. The high sequence diverge nce and evidence of gross rearrangements indicate that the Xp/Yp telom eric region has evolved faster than the rest of the genome.