A molecular method for detecting the presence of the human Y chromosome

The presence of the human Y chromosome can be inferred from the detection of a male-specific 3.4-Kb band generated by digestion with the restriction enzyme Hae III. However, direct visualization of this band is sometimes difficult owing to high background of DNA fragments common to both sexes, and Y chromosome length polymorphism. We have shown that the 3.4-Kb band can be detected by filter hybridization to a large DNA fragment (greater than 20 Kb) also generated by Hae III digestion. Since this large DNA fragment is easily isolated from either sex, it should prove useful to determine sex when chromosome analysis is impractical.