Conservation of intronic minisatellite polymorphisms in the SCK1/SHC2 gene of Hominidae

The neuronally expressed Shc adaptor homolog SCK1/SHC2 gene contains an unusually high number of minisatellites. In humans, twelve different minisatellite sequences are located in introns of SCK1/SHC2 and ten of them are highly polymorphic. Here we used primers developed for humans to screen ten intronic loci of SCK1/SHC2 in chimpanzee and gorilla, and undertook a comprehensive analysis of the genomic sequence to address the evolutionary events driving these variable repeats. All ten loci amplified in chimpanzee and gorilla contained hypervariable and low-variability minisatellites. The human polymorphic locus TR1 was monomorphic in chimpanzee and gorilla, but we detected polymorphic alleles in these apes for the human monomorphic TR7 locus. When we examined the repeat size among these hominoids, there was no consistent variation by length from humans to great apes. In spite of the inconsistent evolutionary dynamics in repeat length variation, exon 16 was highly conserved between humans and great apes. These results suggest that non-coding intronic minisatellites do not show a consistent evolutionary paradigm but evolved with different patterns among each minisatellite locus. These findings provide important insight for minisatellite conservation during hominoid evolution.