Cell-Free DNA Screening: Complexities and Challenges of Clinical Implementation

Screening for fetal aneuploidy in pregnant women using cell-free DNA has increased dramatically since the technology became commercially available in 2011. Since that time, numerous trials have demonstrated high sensitivity and specificity to screen for common aneuploidies in high-risk populations. Studies assessing the performance of these tests in low-risk populations have also demonstrated improved detection rates compared with traditional, serum-based screening strategies. Concurrent with the increased use of this technology has been a decrease in invasive procedures (amniocentesis and chorionic villus sampling). As the technology becomes more widely understood, available, and utilized, challenges regarding its clinical implementation have become apparent. Some of these challenges include test failures, false-positive and false-negative results, limitations in positive predictive value in low-prevalence populations, and potential maternal health implications of abnormal results. In addition, commercial laboratories are expanding screening beyond common aneuploidies to include microdeletion screening and whole genome screening. This review article is intended to provide the practicing obstetrician with a summary of the complexities of cell-free DNA screening and the challenges of implementing it in the clinical setting

RNA-Sequencing of Umbilical Cord Blood to Investigate Spontaneous Preterm Birth: A Pilot Study

Abstract Objective To analyze the transcriptomic gene expression of umbilical cord blood leukocytes using RNA-sequencing from preterm birth (PTB) and term birth (TB). Study Design Eight women with spontaneous PTB (sPTB) and eight women with unlabored TB were enrolled prospectively. The sPTB and TB cohorts were matched for maternal age, race, mode of delivery, and fetal sex. Cord blood RNA was extracted and a globin depletion protocol was applied, then sequenced on the Illumina HiSeq 4000. Raw read counts were analyzed with DESeq2 to test for gene expression differences between sPTB and TB. Results 148 genes had significant differential expression (q < 0.01). Cell cycle/metabolism gene expression was significantly higher and immune/inflammatory signaling gene expression significantly lower in the sPTB cohort compared with term. In African American (AA) infants, 18 genes specific to cell signaling, neutrophil activity, and major histocompatibility complex type 1 had lower expression in preterm compared with term cohort; the opposite pattern was seen in non-Hispanic Whites (NHWs). Conclusion Compared with term, preterm fetuses have higher cell cycle/metabolism gene expression, suggesting metabolic focus on growth and development. Immune function gene expression in this pilot study is lower in the sPTB group compared with term and differs in AA compared with NHW infants

Capnocytophaga Bacteremia Precipitating Severe Thrombocytopenia and Preterm Labor in an Asplenic Host

Capnocytophaga species are gram-negative bacilli that inhabit mammalian oral surfaces and can cause opportunistic infection, especially in asplenic patients. The species Capnocytophaga canimorsus is particularly associated with dog bites and is known to cause endocarditis, meningitis, and sepsis in the general population. In pregnant patients, infections tied to Capnocytophaga species from human flora have been associated with preterm labor, chorioamnionitis, and neonatal septicemia. There is little known about the effects of zoonotically-acquired Capnocytophaga infection in pregnant patients. In this case report, we present a patient with Capnocytophaga bacteremia acquired after a dog bite associated with profound thrombocytopenia and preterm labor. Dog bites are common in the United States, and we present basic recommendations for management of dog bites in pregnant patients in order to avoid morbidity associated with delay in time to antibiotic treatment of infection as described in this case

Insulin Elevates ID2 Expression in Trophoblasts and Aggravates Preeclampsia in Obese ASB4-Null Mice

Obesity is a risk factor for preeclampsia. We investigated how obesity influences preeclampsia in mice lacking ankyrin-repeat-and-SOCS-box-containing-protein 4 (ASB4), which promotes trophoblast differentiation via degrading the inhibitor of DNA-binding protein 2 (ID2). Asb4−/− mice on normal chow (NC) develop mild preeclampsia-like phenotypes during pregnancy, including hypertension, proteinuria, and reduced litter size. Wild-type (WT) and Asb4−/− females were placed on a high-fat diet (HFD) starting at weaning. At the age of 8–9 weeks, they were mated with WT or Asb4−/− males, and preeclamptic phenotypes were assessed. HFD-WT dams had no obvious adverse outcomes of pregnancy. In contrast, HFD-Asb4−/− dams had significantly more severe preeclampsia-like phenotypes compared to NC-Asb4−/− dams. The HFD increased white fat weights and plasma leptin and insulin levels in Asb4−/− females. In the HFD-Asb4−/− placenta, ID2 amounts doubled without changing the transcript levels, indicating that insulin likely increases ID2 at a level of post-transcription. In human first-trimester trophoblast HTR8/SVneo cells, exposure to insulin, but not to leptin, led to a significant increase in ID2. HFD-induced obesity markedly worsens the preeclampsia-like phenotypes in the absence of ASB4. Our data indicate that hyperinsulinemia perturbs the timely removal of ID2 and interferes with proper trophoblast differentiation, contributing to enhanced preeclampsia