INCREASED MICROSATELLITE VARIABILITY IN MACACA MULATTA COMPARED TO HUMANS DUE TO A LARGE SCALE DELETION/INSERTION EVENT DURING PRIMATE EVOLUTION

Human (GATA)n microsatellites D12S66 and D12S67 could be successfully amplified by polymerase chain reaction (PCR) in various species of apes and monkeys. In 86 unrelated animals of the most intensively studied species Macaca mulatta we demonstrated five alleles at “D12S66” differing in size in increments of 4 bp (159–175 bp), whereas 17 alleles were observed at locus “D12S67”. The alleles of the latter locus are distributed in two separate groups with no alleles of intermediate size. Six alleles were found between 108–128 bp and 11 alleles between 181–249 bp. Mendelian inheritance of the codom-inant alleles was proven by family studies. Sequencing of the “D12S67” locus revealed that the shorter alleles are characterized by a single perfect (GATA)n stretch whereas the longer alleles consist of two blocks of (GATA)n repeats separated by an intervening sequence of 9 bp. The composite structure of the longer alleles closely resembles that of the 12 human D12S67 alleles (229–273 bp). The enormous species variation in the fragment size range, with the smallest allele found in Macaca mulatta (108 bp) and the largest (364 bp) in Gorilla gorilla gorilla strongly indicates that D12S67 has been subjected to recurrent mutations over the course of primate evolution including a large deletion and/ or insertion event.