Rapid determination of fetal sex by deoxyribonucleic acid amplification of Y chromosome-specific sequences.

Rapid fetal sex tests use either dot blot hybridization to Y chromosome-specific (male) repeat sequences or polymerase chain reaction deoxyribonucleic acid amplification of these Y-specific sequences. We have performed 35 fetal sex determinations, 16 by dot blot alone, 13 by polymerase chain reaction alone, and 6 by dot blot and polymerase chain reaction on samples of fetal blood, amniotic fluid, and chorionic villi. All results have been confirmed by karyotyping. Dot blots have given false-positive "male" results three times. In contrast, the polymerase chain reaction has correctly determined fetal sex in every case, even when the dot blot was in error. The Y-specific polymerase chain reaction has been applied to fetal deoxyribonucleic DNA with a chromosome 15; Y translocation to identify the origin of the translocated material. Thus the polymerase chain reaction appears to be a reliable method to rapidly determine fetal sex that also can be used diagnostically to identify translocated Y-chromosomal material.