Circulating free fetal nucleic acids in maternal plasma and preeclampsia

Darwin's Pangenesis and Certain Anomalous Phenomena

Darwin clearly described certain anomalous phenomena, including what he referred to as "the direct action of the male element on the female form" and what we now call xenia and telegony, bud variation (mutation), reversion or atavism, and the inheritance and non-inheritance of mutilation. Some phenomena, particularly xenia, telegony and the inheritance of mutilation, were considered as doubtful phenomena by such authorities as Weismann and Morgan. Over the past 150 year, however, there has been increasing evidence for xenia, which is of great interest and importance in physiological research and plant production. The discoveries of cell-free fetal DNA, sperm RNAs, penetration of sperm into the somatic tissues of the female reproductive tract and the incorporation of exogenous DNA into somatic cells indicate that molecular mechanisms exist for telegony, one of the most controversial issues. Darwin's Pangenesis is the only theory that explains all the different types of phenomena.

Cell-free DNA: the role in pathophysiology and as a biomarker in kidney diseases

Cell-free DNA (cfDNA) is present in various body fluids and originates mostly from blood cells. In specific conditions, circulating cfDNA might be derived from tumours, donor organs after transplantation or from the foetus during pregnancy. The analysis of cfDNA is mainly used for genetic analyses of the source tissue -tumour, foetus or for the early detection of graft rejection. It might serve also as a nonspecific biomarker of tissue damage in critical care medicine. In kidney diseases, cfDNA increases during haemodialysis and indicates cell damage. In patients with renal cell carcinoma, cfDNA in plasma and its integrity is studied for monitoring of tumour growth, the effects of chemotherapy and for prognosis. Urinary cfDNA is highly fragmented, but the technical hurdles can now be overcome and urinary cfDNA is being evaluated as a potential biomarker of renal injury and urinary tract tumours. Beyond its diagnostic application, cfDNA might also be involved in the pathogenesis of diseases affecting the kidneys as shown for systemic lupus, sepsis and some pregnancy-related pathologies. Recent data suggest that increased cfDNA is associated with acute kidney injury. In this review, we discuss the biological characteristics, sources of cfDNA, its potential use as a biomarker as well as its role in the pathogenesis of renal and urinary diseases.

Does rat fetal DNA induce preeclampsia in pregnant rats?

Cell-free fetal DNA in maternal circulation is higher during preeclampsia. It is unclear whether it is the cause or the consequence of the disease. The aim of this study was to prove whether injected rat fetal DNA induces preeclampsia-like symptoms in pregnant Wistar rats. They received daily i.p. injections of water or rat fetal DNA (400 μg) from gestation day 14 to 18. Blood pressure, proteinuria, placental and fetal weight were measured at gestation day 19. Plasma DNase activity, proteinuria and creatinine clearance were assessed. There was no significant difference in any of the measured parameters. The results of this study do not confirm the hypothesis that fetal DNA might induce preeclampsia. This is in contrast to others using human fetal DNA in mice. Further studies should be focused on the effects of fetal DNA from the same species protected from DNase activity.

Role of fetal DNA in preeclampsia (review)

Preeclampsia is an autoimmune disorder characterized by hypertension. It begins with abnormal cytotrophoblast apoptosis, which leads to inflammation and an increase in the levels of anti-angiogenic factors followed by the disruption of the angiogenic status. Increased levels of fetal DNA and RNA coming from the placenta, one of the most commonly affected organs in pregnancies complicated by preeclampsia, have been found in pregnant women with the condition. However, it remains unknown as to whether this is a cause or a consequence of preeclampsia. Few studies have been carried out on preeclampsia in which an animal model of preeclampsia was induced by an injection of different types of DNA that are mimic fetal DNA and provoke inflammation through Toll-like receptor 9 (TLR9) or cyclic guanosine monophosphate-adenosine monophosphate (cGAMP). The specific mechanisms involved in the development of preeclampsia are not yet fully understood. It is hypothesized that the presence of different fragments of fetal DNA in maternal plasma may cause for the development of preeclampsia. The function of DNase during preeclampsia also remains unresolved. Studies have suggested that its activity is decreased or the DNA is protected against its effects. Further research is required to uncover the pathogenesis of preeclampsia and focus more on the condition of patients with the condition.

Fetal genes in mother's blood: a novel mechanism for telegony?

Telegony is a discredited genetic phenomenon that a previous male may influence the characteristics of offspring subsequently borne by the same female to another male. Although its reality was acknowledged by such authorities as Charles Darwin and Herbert Spencer, it has been met with skepticism because of a lack of understanding of the theoretical basis for telegony. With the discovery of fetal genes in mother's blood, the penetration of somatic cells by sperm, and the ability of RNA to program genome rearrangement, mechanisms might exist for telegony.