Isolation of human Y chromosomal major repetitive sequences from a flow-sorted Y chromosomal library.

The human Y chromosome is highly heterochromatic and consists mainly of repetitive sequences, of which 3.4 kb HaeIII or EcoR1 fragments represent the most abundant species. From a flow-sorted human Y chromosomal library, we isolated 15 clones containing sequences highly homologous to this major repetitive sequence. Although the size of inserts varied from 0.7 to 3.8 kb, their hybridization patterns to human genomic DNA were indistinguishable from each other. These repetitive sequences unambiguously detected the presence of the Y chromosome in a male-female DNA mixture of which 5% was derived from male cells. Thus, these clones would be useful molecular tools to detect contaminating male cells in clinical materials.