Fetal Sex Identification in Maternal Plasma by Means of Short Tandem Repeats on Chromosome X

A reliable assay for rapidly defining transplacental metastasis using quantitative PCR

To choose the most appropriate treatment for children affected by a transplacental metastasis, it is crucial to ascertain the maternal origin of the tumor. Up-to-date conclusive diagnosis is generally achieved through fluorescence in situ hybridization or karyotyping analysis. Herein, we report an alternative, reliable assay for rapidly defining vertical cancer transmission to the fetus by using quantitative polymerase chain reaction. Our assay indicates that quantification of the copy number of the sex chromosomes by specific short tandem repeats markers, in genomic DNA purified from the tumor biopsy cells, could be used to correctly evaluate transplacental metastasis events.

Circulating nucleic acids in plasma and serum: applications in diagnostic techniques for noninvasive prenatal diagnosis

The analysis of fetal nucleic acids in maternal blood 13 years ago has led to the initiation of noninvasive methods for the early determination of fetal gender, rhesus D status, and a number of aneuploid disorders and hemoglobinopathies. Subsequently, a comparatively large quantity of fetal DNA and RNA has been demonstrated in amniotic fluid as well as small amounts in premature infant saliva. The DNA and RNA in amniotic fluid has permitted an analysis of core transcriptomes, whilst the DNA and RNA in saliva allows the early detection and treatment monitoring of fetal developmental problems. These aspects are discussed together with the methodology and limits of analysis for noninvasive prenatal diagnosis in predictive, preventive, and personalized medicine.

Non-invasive prenatal diagnostic test accuracy for fetal sex using cell-free DNA a review and meta-analysis

Background

Cell-free fetal DNA (cffDNA) can be detected in maternal blood during pregnancy, opening the possibility of early non-invasive prenatal diagnosis for a variety of genetic conditions. Since 1997, many studies have examined the accuracy of prenatal fetal sex determination using cffDNA, particularly for pregnancies at risk of an X-linked condition. Here we report a review and meta-analysis of the published literature to evaluate the use of cffDNA for prenatal determination (diagnosis) of fetal sex. We applied a sensitive search of multiple bibliographic databases including PubMed (MEDLINE), EMBASE, the Cochrane library and Web of Science.

Results

Ninety studies, incorporating 9,965 pregnancies and 10,587 fetal sex results met our inclusion criteria. Overall mean sensitivity was 96.6% (95% credible interval 95.2% to 97.7%) and mean specificity was 98.9% (95% CI = 98.1% to 99.4%). These results vary very little with trimester or week of testing, indicating that the performance of the test is reliably high.

Conclusions

Based on this review and meta-analysis we conclude that fetal sex can be determined with a high level of accuracy by analyzing cffDNA. Using cffDNA in prenatal diagnosis to replace or complement existing invasive methods can remove or reduce the risk of miscarriage. Future work should concentrate on the economic and ethical considerations of implementing an early non-invasive test for fetal sex.

Sex determination using free fetal DNA at early gestational ages: a comparison between a modified mini-STR genotyping method and real-time PCR

OBJECTIVE

Recently the use of free fetal deoxyribonucleic acid (DNA) in maternal plasma and serum has been applicable for noninvasive prenatal genetic diagnosis. In this study, we applied a new algorithmic base conventional polymerase chain reaction (PCR) genotyping method and also real-time PCR for detecting fetal X and Y-chromosome sequences in maternal plasma to determine fetal sex in pregnant women in their early gestational ages (5-13 weeks). Finally, we compared the efficiency of each method in sex determination.

STUDY DESIGN

DNA was extracted from 106 pregnant women and their husbands' blood samples. Fetus mini-short tandem repeat (STR) genotyping was accomplished through amplification of 19 mini-STRs and 3 non-STR markers using conventional PCR followed by polyacrylamide gel electrophoresis analysis. Simultaneously, TaqMan real-time PCR was done with the use of DYS14-specific primers and probe.

RESULTS

In conventional PCR method, 47 cases were diagnosed to be male and 49 to be female. In comparison, real-time PCR amplified DYS14 (Y-marker) sequences in 45 pregnant women plasma samples. Sensitivity and specificity were calculated to be 95.9% and 98% for conventional PCR and 91.8% and 100% for real-time PCR method, respectively.

CONCLUSION

According to our study, the conventional PCR method was more sensitive than real-time PCR and it could be employed in future clinical diagnostics singly or in combination with real-time PCR.

Detection of transplacental melanoma metastasis using quantitative PCR

To choose the most appropriate treatment for children affected by a transplacental metastasis, it is crucial to ascertain the maternal origin of the tumor. Up-to-date conclusive diagnosis is generally achieved through fluorescence in situ hybridization or karyotyping analysis. Herein, we report an alternative, reliable assay for rapidly defining vertical cancer transmission to the fetus by using quantitative polymerase chain reaction. Our assay indicates that quantification of the copy number of the sex chromosomes by specific short tandem repeats markers, in genomic DNA purified from the tumor biopsy cells, could be used to correctly evaluate transplacental metastasis events.