Sex determination of blood stains with a recombinant DNA probe: comparison with radioactive and non-radioactive labeling methods.

A recombinant DNA probe hybridizing specifically to human repeat DNA sequence (pHY10) of which about 3000 copies are present on the Y chromosome was used for sex determination of degraded DNA samples of blood stains. Human blood stains of male and female origin were readily differentiated with the pHY10 DNA probe. This radioactive technique enabled reliable and sensitive sex determination from blood or dried blood stains greater than 20 years old. Less than 1 microliter of blood or 1 piece of 0.5 cm length thread of blood stain from cotton fabric was sufficient for the test using dot blot hybridization. Compared with the radioactive labeling method, the photobiotin labeling method showed one thirtieth to one fiftieth lower sensitivity and presented some problems which are expected to be resolvable.