highly sensitive conventional pcr testing of free fetal dna in maternal serum for non-invasive fetal sex determination

background: free fetal dna (ffd) in maternal plasma/serum has increasingly become the source of fetal material for diagnostic purposes in recent years. this source of fetal material can be used for sex determination. rh typing paternally inherited sequences and compound heterozygosity. reports on the lack of consistent pcr amplification of y-chromosome sequences of ffd in maternal plasma/serum have led diagnostic services to the use of real-time pcr for improved sensitivity of sex determination. we report the use of conventional pcr for fetal sex determination with high sensitivity and reporoducibility.  methods: peripheral blood samples were obtained from 21 pregnant volunteers during 4-29 weeks of gestation. a healthy man and 52 healthy non-pregnant women were investigated in this study as controls. all the samples were collected at random. fetal gender was determined by conventional pcr to detect a y-chromosomal sequence (dyz1) in maternal serum and confirmed by amniocentesis or after delivery.  results: fetus-derived y sequences were detected in 16 out of 17 maternal serum samples with male fetuses and none of the 4 women bearing female fetuses had positive results. the sensitivity of our pcr reached >95%, and the specificity reached >96% (y signal detected in only 2 out of 52 female samples studied).  conclusion: our report on the improved sensitivity of y- chromosome pcr simplifies routine sex determination in diagnostic laboratories without the use of real-time pcr.