Noninvasive Diagnosis of Fetal Gender: Utility of Combining DYS14 and SRY.

OBJECTIVE: Diagnosis of fetal gender early in pregnancy is very useful as it would prevent invasive fetal sampling in almost half the cases at risk of inheriting X-linked disorders or those affecting sexual differentiation. Noninvasive prenatal diagnosis (NIPD) using circulating cell-free fetal (cff) DNA from maternal circulation has emerged as a useful alternative to existing methods for prenatal diagnosis of gender. NIPD eliminates the risk of miscarriage from invasive prenatal diagnosis and the necessity of possessing specialized obstetric skills for fetal tissue sampling. The aim of this study was to compare two Y chromosome markers-SRY and DYS14-for their utility in the diagnosis of fetal gender.

SUBJECTS AND METHODS: Forty-eight plasma samples from pregnant women between 9 and 25 weeks of gestation were analyzed. Real-time polymerase chain reaction was performed on cff DNA extracted from maternal plasma to detect fetal Y chromosome with SRY (n=27) and DYS14 (n=48) markers.

RESULTS: We observed 100% sensitivity and 85.6% specificity in noninvasive Y chromosome detection with the combined use of DYS14 and SRY markers (n=27) compared with the results obtained on using DYS14 (n=48 sensitivity 94%; specificity 71.4%) and SRY (n=27, sensitivity 84%; specificity 92.8%) markers alone.

CONCLUSION: Our results show that the test performance improved with the employment of two Y-amplification assays.