Rapid diagnosis of triploidy of maternal origin using fluorescent PCR and DNA fragment analysis in the third trimester of pregnancy

Rare case of exomphalos complicated with umbilical cord teratoma in a fetus with trisomy 13

An exomphalos containing unusual solid and cystic mass was diagnosed during a routine ultrasound examination in the 17th week of gestation. Further investigations were planned but the pregnancy was terminated. The fetopathological examination revealed an umbilical cord teratoma. Although this entity is very rare it should be emphasized as a possible differential diagnosis when cystic lesion of the cord is detected. Large teratomas associated with abdominal wall defect may have poor fetal outcome and can be associated with structural and chromosomal abnormalities. In our case trisomy 13 was diagnosed.

Application of quantitative fluorescent PCR with short tandem repeat markers to the study of aneuploidies in spontaneous miscarriages

BACKGROUND

Aneuploidies involve approximately 80% of chromosomal anomalies found in spontaneous miscarriages. Since cytogenetic studies show high rates of failure, we have incorporated the quantitative fluorescent polymerase chain reaction (QF-PCR) technique to the study of numerical chromosome anomalies in miscarriages.

METHODS

Multiplex and simple QF-PCR assays have been performed on 160 miscarriage and 34 parental DNA samples analysing specific short tandem repeat (STR) markers for chromosomes 2, 7, 13, 15, 16, 18, 21, 22 and X. Cases successfully karyotyped were used as controls in our study.

RESULTS

While maternal contamination could be detected in such cases, a molecular result was obtained for 94% of miscarriages without a cytogenetic one. Thirty-six per cent of them were diagnosed with numerical chromosome anomalies. Parental origin of the extra chromosome and the error stage of meiosis could be also determined.

CONCLUSIONS

QF-PCR represents a useful and reliable tool to diagnose aneuploidies in spontaneous miscarriages. It provides information about parental and meiotic origin of anomaly, allowing an appropriate genetic counselling.

Isolation of epsilon-haemoglobin-chain positive fetal cells with micromanipulation for prenatal diagnosis

OBJECTIVES

The isolation and analysis of fetal cells in maternal blood during pregnancy is under investigation as a means of noninvasive prenatal diagnosis. The aim of our study was to detect fetal gender from maternal peripherial blood samples during pregnancy with the detection and analysis of epsilon-haemoglobin-chain positive fetal nucleated red blood cells (NRBCs) collected by a micromanipulator. Here we report our first results.

DESIGN AND METHODS

We obtained maternal blood from 14 singleton pregnancies. After a double density gradient separation, magnetic activated cell sorting was performed by positive selection for nucleated red blood cells with anti-CD71. With the help of this enrichment step, followed by immunophenotyping with an anti-haemoglobin-epsilon monoclonal antibody, the isolation of the epsilon haemoglobin chain positive cells with micromanipulation could be done. We performed single cell fluorescent PCR analysis of these cells; we used primers for the amelogenin gene to detect fetal gender. We compared our findings with the results of amniocentesis.

RESULTS

Fetal gender was successfully determined in 11 out of 14 cases; among them, in 2 cases with Klinefelter syndrome (47,XXY).

CONCLUSION

The results of our study suggest that micromanipulation and QF-PCR analysis of anti-haemoglobin-epsilon fluorescent antibody stained fetal cells from maternal blood can be useful in prenatal diagnosis to detect fetal gender and promising to be improved to detect chromosomal abnormalities.