Characterization of a cloned DNA sequence that is present at centromeres of all human autosomes and the X chromosome and shows polymorphic variation.

We have identified a human DNA recombinant (p308) with a 3.0-kilobase (kb) BamHI insert that hybridizes in situ exclusively to the centromeric region of all human autosomes and the X chromosome. This highly repetitive sequence is significantly enriched on several chromosomes, most prominently on chromosome 6. In all individuals, the majority of genomic repeats are organized as tandem 3.0-kb BamHI repeats, each containing one Taq I site; the others are organized into BamHI and Taq I repeats of variable size that have some chromosome specificity. Using mouse-human hybrids, we have defined the specific organization of this sequence on chromosomes 6, 3, and X. In some individuals, there are differences in the number and nature of the tandem repeats. These polymorphisms segregate in families as if chromosome specific. Although variable from one chromosome to another, 308 contains sequences homologous to DNA present in centric heterochromatin of essentially all human chromosomes and is evolutionarily conserved. Therefore, a significant component of pericentric DNA is similar for all human chromosomes.