Fertility and sterility
-
Fertility and sterility · Mar 2013
ReviewCell-free fetal DNA and maternal serum analytes for monitoring embryonic and fetal status.
Biomarkers can be employed for screening for fetal genetic disorders, identifying individuals at sufficiently high risk for a confirmatory invasive procedure. In this article we discuss prenatal genetic aneuploidy screening. Maternal serum analytes and ultrasound have long been routinely offered, providing detection rates of 80% to 93% for trisomy 21; however, an invasive procedure (false-positive) must be performed in 5% of pregnancies screened. ⋯ Current emphasis is focused predominantly on cell-free fetal DNA, which accounts for 5% to 10% of total cell-free DNA in maternal blood. Analysis of maternal blood results in detection rates of over 99% for fetal trisomy 21, and also very high rates for trisomy 18 and sex chromosomal abnormalities. Such detection rates are substantively higher than with maternal serum analytes, and are accompanied by a much lower (<1%) false-positive rate.
-
Several types of epigenetic marks facilitate the complex patterning required for normal human development. These epigenetic marks include DNA methylation at CpG dinucleotides, covalent modifications of histone proteins, and noncoding RNAs (ncRNAs). They function in a highly orchestrated manner, regulating mitotically heritable differences in gene expression potential without altering the primary DNA sequence. ⋯ Two specific types of epigenetic regulation established in early development include X-chromosome inactivation and genomic imprinting; they regulate gene expression in a dosage-dependent and parent-of-origin-specific manner, respectively. Both genetic and environmental factors impact epigenetic marks, generating phenotypic variation that ranges from normal variation to human disease. Aberrant epigenetic patterning can lead to a variety of human disorders, including subfertility and imprinting disorders.