Single-copy DNA sequences specific for the human Y chromosome.

Detailed studies of the role of the mammalian Y chromosome in primary sex determination are limited by the lack of available specific markers and by the fragmentary knowledge of its molecular organization. Y-derived unique DNA sequences could provide powerful analytical tools to probe directly the structure of the Y chromosome and provide a means of searching for specific expressed sequences. We report here the construction of a partial cosmid library of the human Y chromosome. From independent clones we have isolated 30 unrelated DNA probes that are free of highly repetitive sequences, and have examined their reaction pattern on male and female genomic blots. Of the 30 probes tested, six were specific for the Y chromosome. In addition, four probes gave a male-female differential hybridization pattern and the remaining 20, although Y-derived, reacted similarly with both male and female DNA.