Use of maternal plasma for non-invasive prenatal diagnosis of fetal ABO genotypes

Rapid molecular prenatal diagnosis of spondyloepiphyseal dysplasia congenita by PCR-SSP assay

Heterozygous mutations of COL2A1 gene are responsible for type II collagenopathies. The common skeletal phenotypes include achondrogenesis type II, hypochondrogenesis, Stickler dysplasia, Kniest dysplasia, late onset spondyloepiphyseal dysplasia, and spondyloepiphyseal dysplasia congenita (SEDC). Prevention of SEDC can be achieved by prenatal diagnosis. This study reports the first rapid molecular prenatal diagnosis of SEDC performed in China by polymerase chain reaction sequence-specific primer (PCR-SSP) analysis. The pregnant woman we previously reported with SEDC carried the G to A substitution at nucleotide 1510 in exon 23 of COL2A1 gene, which caused a change from glycine to serine at codon 504 (G504S). By the time the woman got pregnant again, she had terminated two pregnancies and still had no child. In the first pregnancy, the molecular mutation of the family was not yet identified, and therefore prenatal diagnosis was unable to be performed by DNA analysis. In the second pregnancy, G504S mutation was found from fetal DNA. At the time of her third pregnancy, the woman and her husband became extremely worried about the potential SEDC for the fetus. For this reason, a quick and reliable molecular prenatal diagnosis of SEDC was performed by a PCR-SSP on an amniocyte sample collected at the 14th week of pregnancy. No mutation of the fetal DNA was identified. The result was obtained within 24 h after the sample was collected. The technique could be applied in confirmatory diagnosis and prenatal diagnosis for the affected family.

The use of cell-free fetal nucleic acids in maternal blood for non-invasive prenatal diagnosis

BACKGROUND

Cell-free fetal nucleic acids (cffNA) can be detected in the maternal circulation during pregnancy, potentially offering an excellent method for early non-invasive prenatal diagnosis (NIPD) of the genetic status of a fetus. Using molecular techniques, fetal DNA and RNA can be detected from 5 weeks gestation and are rapidly cleared from the circulation following birth.

METHODS

We searched PubMed systematically using keywords free fetal DNA and NIPD. Reference lists from relevant papers were also searched to ensure comprehensive coverage of the area.

RESULTS

Cell-free fetal DNA comprises only 3-6% of the total circulating cell-free DNA, therefore diagnoses are primarily limited to those caused by paternally inherited sequences as well as conditions that can be inferred by the unique gene expression patterns in the fetus and placenta. Broadly, the potential applications of this technology fall into two categories: first, high genetic risk families with inheritable monogenic diseases, including sex determination in cases at risk of X-linked diseases and detection of specific paternally inherited single gene disorders; and second, routine antenatal care offered to all pregnant women, including prenatal screening/diagnosis for aneuploidy, particularly Down syndrome (DS), and diagnosis of Rhesus factor status in RhD negative women. Already sex determination and Rhesus factor diagnosis are nearing translation into clinical practice for high-risk individuals.

CONCLUSIONS

The analysis of cffNA may allow NIPD for a variety of genetic conditions and may in future form part of national antenatal screening programmes for DS and other common genetic disorders.