Fetal and placental chromosomal mosaicism revealed by QF-PCR in severe IUGR pregnancies

A number of genetic and environmental factors are taken into account as responsible for intrauterine growth restriction (IUGR); nevertheless, the relevance of genetic alteration in IUGR aetiology remains to be determined. The aim of this study was to investigate using a combined cytogenetic-molecular approach, improved by a new application of QF-PCR method, the presence of mosaic chromosomal changes in fetal/placental samples from 12 pregnancies with unexplained severe IUGR. This multiple approach allowed us to reveal and quantify subtle chromosomal mosaicisms with less than 5% of trisomic cells even in cases in which cytogenetic and FISH analyses failed to reveal them. These are three pregnancies with a mosaic trisomy for chromosomes 7, 2 and 14; the former case presented matUPD7 and was previously described in this journal (Placenta 22 (2001) 813) in association with pre- and postnatal growth restriction. It is intriguing that chromosomes 7, 2 and 14 are known or suspected to harbour imprinted genes, so that an unbalanced gene dosage in a subset of cells during embryonic development could lead to an early impairment of placental function. Our findings indicate that extensive molecular and cytogenetic studies of IUGR fetal and placental tissues are necessary to reveal at least part of the heterogeneous genetic lesions implicated in IUGR phenotypes.     

Placental dysfunction and fetal programming: the importance of placental size, shape, histopathology, and molecular composition

Normal function of the placenta is pivotal for optimal fetal growth and development. Fetal programming commonly is associated with placental dysfunction that predisposes to obstetric complications and suboptimal fetal outcomes. We consider several clinical phenotypes for placental dysfunction that likely predispose to fetal programming. Some of these reflect abnormal development of the chorioallantoic placenta in size, shape, or histopathology. Others result when exogenous stressors in the maternal environment combine with maladaptation of the placental response to yield small placentas with limited reserve, as typical of early-onset intrauterine growth restriction and preeclampsia. Still others reflect epigenetic changes, including altered expression of imprinted genes, altered enzymatic activity, or altered efficiencies in nutrient transport. Although the human placenta is a transient organ that persists only 9 months, the effects of this organ on the offspring remain for a lifetime.     

Fetal growth restriction due to placental disease

Normal fetal growth depends on the genetically predetermined growth potential and its modulation by the health of the fetus, placenta and the mother. Fetuses that are small because of intrauterine growth restriction (IUGR) are at higher risk for poor perinatal and long-term outcome than those who are appropriately grown. Of the many potential underlying processes that may result in IUGR, placental disease is clinically the most relevant. Fetal cardiovascular and behavioral responses to placental insufficiency and the metabolic status are interrelated. The concurrent evaluation of fetal biometry, amniotic fluid volume, heart rate patterns, arterial and venous Doppler, and biophysical variables therefore allow the most comprehensive fetal evaluation in IUGR. In the absence of successful intrauterine therapy, the timing of delivery is perhaps the most critical aspect of the antenatal management. A discussion of the fetal responses to placental insufficiency and a management protocol that accounts for multiple Doppler and biophysical parameters as well as gestational age is provided in this review.     

Pathophysiology of fetal growth restriction: implications for diagnosis and surveillance

Normal fetal growth depends on the genetically predetermined growth potential and is modulated by fetal, placental, maternal, and external factors. Fetuses with intrauterine growth restriction (IUGR) are at high risk for poor short- and long-term outcome. Although there are many underlying etiologies, IUGR resulting from placental insufficiency is most relevant clinically because outcome could be altered by appropriate diagnosis and timely delivery. A diagnostic approach that aims to separate IUGR resulting from placental disease from constitutionally small fetuses and those with other underlying etiologies (e.g., aneuploidy, viral infection, nonaneuploid syndromes) needs to integrate multiple imaging modalities. In placental-based IUGR, cardiovascular and behavioral responses are interrelated with the disease severity. Ultrasound assessment of fetal anatomy, amniotic fluid volume, and growth is complementary to the Doppler investigation of fetoplacental blood flow dynamics. A diagnostic approach to IUGR combining these modalities is presented in this review. TARGET AUDIENCE: Obstetricians & Gynecologists, Family Physicians. LEARNING OBJECTIVES: After completion of this article, the reader should be able to describe the development of the placental interface, to outline the mechanisms of placental insufficiency, and to list the manifestations of placental insufficiency and the tests that can be used to diagnose fetal growth restriction.     

Review: Neuroinflammation in intrauterine growth restriction

Disruption to the maternal environment during pregnancy from events such as hypoxia, stress, toxins, inflammation, and reduced placental blood flow can affect fetal development. Intrauterine growth restriction (IUGR) is commonly caused by chronic placental insufficiency, interrupting supply of oxygen and nutrients to the fetus resulting in abnormal fetal growth. IUGR is a major cause of perinatal morbidity and mortality, occurring in approximately 5–10% of pregnancies. The fetal brain is particularly vulnerable in IUGR and there is an increased risk of long-term neurological disorders including cerebral palsy, epilepsy, learning difficulties, behavioural difficulties and psychiatric diagnoses. Few studies have focused on how growth restriction interferes with normal brain development in the IUGR neonate but recent studies in growth restricted animal models demonstrate increased neuroinflammation. This review describes the role of neuroinflammation in the progression of brain injury in growth restricted neonates. Identifying the mediators responsible for alterations in brain development in the IUGR infant is key to prevention and treatment of brain injury in these infants.     

Confined placental mosaicism for trisomy 14 and maternal uniparental disomy in association with elevated second trimester maternal serum human chorionic gonadotrophin and third trimester fetal growth restriction

A case of confined placental mosaicism (CPM) and maternal uniparental isodisomy 14 identified after placental karyotype revealed trisomy 14 in a newborn with intrauterine growth restriction (IUGR) and minor dysmorphic features is reported. During the second trimester of the pregnancy, multiple marker screening revealed an increased risk for Down syndrome of > 1 in 10. The maternal serum human chorionic gonadotrophin (MShCG) was markedly elevated at 4.19 MoM. Amniocentesis revealed a normal 46,XX karyotype. Fetal growth restriction has been associated with elevated MShCG and placental aneuploidy with CPM for chromosomes 2, 7, 9 and 16. The present case of CPM for chromosome 14 was also associated with fetal growth restriction and elevated second trimester MShCG, suggesting a common link. Further studies need to be done to determine if indeed elevation of second trimester MShCG is associated with increased risk of CPM. The present case again demonstrates the need to perform placental karyotype in unexplained fetal growth restriction.     

Correlation of fetal DNA levels in maternal plasma with Doppler status in pathological pregnancies

OBJECTIVES: To evaluate whether intrauterine growth restriction (IUGR) as seen in preeclampsia is associated with high levels of fetal DNA in maternal circulation, and whether fetal DNA is related to altered uterine and/or umbilical artery Doppler velocimetry. METHODS: Fetal DNA quantification was performed by real-time PCR on SRY sequences in 64 male-bearing pregnant women with IUGR and/or preeclampsia and 89 controls. RESULTS: Fetal DNA content was significantly elevated in IUGR pregnancies similar to preeclampsia and correlated with altered umbilical Doppler velocimetry, while no correlation was found with uterine Doppler status. CONCLUSION: Increased fetal DNA levels in maternal plasma may be a sign of placental or fetal pathology even in the presence of normal uterine Doppler velocimetry, allowing a more precise diagnostic evaluation. The finding that elevated fetal DNA in IUGR pregnancies correlates with abnormal umbilical Doppler velocimetry suggests that fetal DNA release is associated more with fetal chronic hypoxia than with fetal size.     

Molecular mechanisms of intrauterine growth restriction

Intrauterine growth restriction (IUGR) is a pregnancy specific disease characterized by decreased growth rate of fetus than the normal growth potential at particular gestational age. In the current scenario it is a leading cause of fetal and neonatal morbidity and mortality. In the last decade exhilarating experimental studies from several laboratories have provided fascinating proof for comprehension of molecular basis of IUGR. Atypical expression of enzymes governed by TGFβ causes the placental apoptosis and altered expression of TGFβ due to hyper alimentation causes impairment of lung function. Crosstalk of cAMP with protein kinases plays a prominent role in the regulation of cortisol levels. Increasing levels of NOD1 proteins leads to development of IUGR by increasing the levels of inflammatory mediators. Increase in leptin synthesis in placental trophoblast cells is associated with IUGR. In this review, we emphasize on the regulatory mechanisms of IUGR and its associated diseases. They may help improve the in-utero fetal growth and provide a better therapeutic intervention for prevention and treatment of IUGR.     

Relevance of genomic imprinting in intrauterine human growth expression of CDKN1C,H19, IGF2, KCNQ1 and PHLDA2 imprinted genes

Purpose

To study the relationship of imprinted gene expression (CDKN1C, H19, IGF2, KCNQ1 and PHLDA2) with human fetal growth.

Methods

RNA was extracted from fetuses with intrauterine growth restriction (IUGR) and from the controls without growth restriction. The gene expression pattern of CDKN1C, H19, IGF2, KCNQ1 and PHLDA2 genes was evaluated using RT-PCR. MS-MLPA was also performed to assess the IC1 and IC2 DNA methylation status on chromosome 11p15.5.

Results

The samples were divided according to their tissue type in placental or fetal tissue. Within each group, IUGR cases and controls were compared. In the IUGR cases, in both fetal and placental tissue groups IGF2 was observed to be down regulated. In another approach, the samples were divided in IUGR and control groups and for each of them placental and fetal tissue was compared. Within the IUGR group up regulation of CDKN1C, KCNQ1, and PHLDA2 was determined in placental samples. IUGR group presented a statistically lower methylation status in both IC1 and in IC2. Regarding differences between fetal and placental samples within this group, methylation status of placental samples was statistically significant down regulated in the imprinting center 1 (IC1).

Conclusions

Genomic imprinting is a phenomenon that plays an important role in fetal and placental development. This study emphasizes the importance of imprinted genes during pregnancy. Differences between tissues could reflect different mechanisms, either compensatory or adverse, that should be investigated in more detail.

Electronic supplementary material

The online version of this article (doi:10.1007/s10815-014-0278-0) contains supplementary material, which is available to authorized users.     

Genetic,metabolic and endocrine aspect of intrauterine growth restriction: an update

Intrauterine growth restriction (IUGR) is defined as growth of fetus below its in-utero growth potential. Small for gestational age (SGA) is defined as newborn with birth weight less than 10th centile as per the gestational age, sex and race. There exists major difference between IUGR and SGA. IUGR infants have multiple short-term and long-term complications and IUGR is a silent cause of various morbidities and mortalities in these infants. IUGR/SGA is usually end results of maternal, placental, fetal and genetic causes. With the advance of molecular biology, the list genetic cause of IUGR is increasing and these genetic causes include maternal, placental and fetal genes. Several metabolic and endocrinal causes are also responsible to cause IUGR. In this review, we will try to cover genetic, metabolic and endocrinal factors that are responsible for IUGR.     

Intrauterine Growth Restriction: Implications for Placental Metabolism and Transport. A Review

Intrauterine growth restriction (IUGR) correlates with a specific placental phenotype, associated with defects in placental transport functions, that lead to fetal undernutrition. Both placental metabolism and transport may be affected, thus modifying the normal supply of nutrients. Models to investigate placental function may either couple or separate metabolism and transport. In human pregnancies, nutrient concentrations can be measured at the time of delivery or at cordocentesis in the umbilical vessels connecting the fetus to the placenta. The kinetics of placental transport can be evaluated in vivo using stable isotopes, i.e. infusing ¹³C labelled nutrient in the mother by bolus or steady state techniques prior to cordocentesis or cesarean section. In vitro studies, using the model of the dually perfused human placenta or investigating the activity of transporters in the placental membranes have also significantly contributed to our understanding of placental function.In IUGR, the placental supply of amino acids is significantly reduced independently from the severity of growth restriction and from the presence of hypoxia. Moreover, maternal–fetal gradients of glucose are increased in severe IUGR fetuses, i.e. those with alterations of umbilical blood flows, and reduced conversion ratios of long chain-polyunsaturated fatty acids (LC-PUFA) from their parent fatty acids have been demonstrated.This review summarizes the current knowledge about placental metabolism and transport in IUGR pregnancies and the relationship with severity of the disease.     

Intrauterine Wachstumsrestriktion

The term “intrauterine growth restriction” (IUGR) defines fetuses who fail to realize their genetically endowed growth potential. Small for gestational age (SGA) fetuses (abdominal circumference or estimated fetal weight below the 10th percentile) have to be distinguished from IUGR fetuses (SGA fetuses having abnormal umbilical artery Doppler). About 50% of SGA fetuses also have IUGR. The birth weight of 25% of IUGR fetuses is above the 10th percentile. Fetal growth is regulated by genetic and environmental factors of parental, fetal, and placental origin. In more than 50% of cases, IUGR is associated with risk factors (medical history, clinical findings). The diagnosis relies on fetal biometry; however, the sensitivity in low-risk groups is only 30–40%. Diagnostic procedures should always include Doppler sonography of the fetomaternal circulation, detailed assessment of the fetal organs by ultrasound, and, optionally, serological examinations to exclude infections and determine the karyotype.     

Noninvasive assessment of fetal aortic blood flow in normal and abnormal pregnancies

Fetal blood flow measurements have a good capacity to predict unfavorable fetal outcome, especially chronic distress accompanied by IUGR. The descending thoracic aorta is of particular interest in these studies and the results reflect peripheral vascular resistance, both in the fetal placental circulation and in fetal abdominal and peripheral areas. A pathologic finding in blood velocity waveforms, especially an absent end-diastolic velocity, seems to be an early and consistent alteration that precedes the occurrence of a pathologic CTG pattern by at least several days. According to our experience, the main benefit of fetal blood flow studies is in differentiation between IUGR fetuses, in which growth retardation is accompanied by some degree of fetal hypoxia, and those cases in which the small size does not signify an immediate threat to fetal well-being. Nevertheless, there are still a number of diagnostic and practical problems. The individual fetal capability to tolerate impaired fetal placental circulation and hemodynamic redistribution is variable. Hence, it is impossible to make clinical decisions based only on hemodynamic findings; we also need diagnostic support from other methods (evaluation of fetal structures by ultrasound, CTG registration, rapid fetal karyotyping, and fetal acid-base status). In some cases, pathologic blood velocity waveforms develop as soon as at weeks 24-27, and because of the lack of reliable therapeutic methods to improve fetal condition, the selection of an ideal time of delivery is often a compromise between threatened fetal asphyxia and prematurity.(ABSTRACT TRUNCATED AT 250 WORDS)     

Intrauterine growth restriction in a rodent model and developmental programming of the metabolic syndrome: a critical appraisal of the experimental evidence

Research on intrauterine growth restriction (IUGR) and subsequent development of obesity, type 2 diabetes and the metabolic syndrome is rapidly expanding, and potential implications for primary prevention are considerable. We have critically appraised one of the experimental animal models frequently used as mimic of human fetal growth restriction, which involves bilateral ligation of the uterine artery in rats (Lig). Our experimental study showed that Lig performed on day 17 of pregnancy neither leads to IUGR nor to neonatal catch-up growth, an important pathogenetic co-factor in humans. Meta-analysis of the literature revealed domination by studies in which Lig pups with IUGR were actively selected. Accordingly, publication bias is evident (p=0.007). Altered placental perfusion--the main cause of IUGR in humans in Western countries--neither led to IUGR nor to neonatal catch-up growth in Lig offspring, i.e., to none of the etiological factors of the human 'small baby syndrome'. Appropriate and reproducible rodent models of IUGR through decreased placental flow remain to be established to uncover the pathophysiological basis of the 'small baby syndrome'. This may lead to new strategies of primary prevention of diabetes, obesity, and the metabolic syndrome.     

Neurodevelopment in children with intrauterine growth restriction: adverse effects and interventions

Intrauterine growth restriction (IUGR) is associated with higher rates of fetal, perinatal, and neonatal morbidity and mortality. The consequences of IUGR include short-term metabolic, hematological and thermal disturbances that lead to metabolic syndrome in children and adults. Additionally, IUGR severely affects short- and long-term fetal brain development and brain function (including motor, cognitive and executive function) and neurobehavior, especially neuropsychology. This review details the adverse effects of IUGR on fetal brain development and discusses intervention strategies.     

Morphologic alterations in ovine placenta and fetal liver following induced severe placental insufficiency

OBJECTIVES: Umbilical-placental embolization with microspheres has been used as a model of placental insufficiency and intrauterine growth restriction (IUGR). However, the effects of embolization on placental structure and organ morphology of the resulting IUGR fetus are relatively unexplored. In this study using ovine fetuses, we determined the location and distribution of microspheres within the placenta and explored the extent of placental and fetal organ morphologic changes induced by placental embolization. We hypothesized that microspheres administered into the umbilical circulation over 4 days would cause placental damage without significant morphologic alterations in fetal kidney or liver. METHODS: Eleven pregnant sheep at 118 +/- 1 (SE) days' gestation were studied. In six fetuses, embolization was induced by injections of 15-microm diameter microspheres on 4 successive days into the fetal descending aorta proximal to the umbilical arteries. Five fetuses served as time controls. RESULTS: In embolized fetuses, microspheres were detected in the placenta embedded in the fetal cytotrophoblastic layer or maternal parenchyma adjacent to villous cytotrophoblasts. Fetal cytotrophoblasts appeared normal except for loss of distinct separation between fetal and maternal cell layers. Microspheres were also detected in the fetal membranes within capillaries. The body weights of embolized fetuses were lower than controls, as were the body weight-normalized liver but not kidney weights. In the liver of the embolized fetuses, the number of hematopoietic cell clusters was markedly reduced, whereas the fetal kidneys appeared normal. CONCLUSIONS: We conclude that after 4 days of umbilical-placental embolization, microspheres were concentrated at the fetal villi proximal to the apical maternal-fetal interface and in the fetal membranes. There were noticeable morphologic changes in the embolized placentas, with no apparent gross damage to the placenta. The reduction in fetal liver weight and liver extramedullary hematopoietic cell abundance associated with embolization may predispose the fetus to alterations in liver function that could persist after birth.     

Fetal growth restriction: a workshop report

Intrauterine growth restriction (IUGR) is associated with significantly increased perinatal morbidity and mortality as well as cardiovascular disease and glucose intolerance in adult life. A number of disorders from genetic to metabolic, vascular, coagulative, autoimmune, as well as infectious, can influence fetal growth by damaging the placenta, leading to IUGR as a result of many possible fetal, placental and maternal disorders. Strict definitions of IUGR and of its severity are needed in order to eventually distinguish among different phenotypes, such as gestational age at onset, degree of growth restriction and presence of hypoxia. This report explores and reviews some of the most recent developments in both clinical and basic research on intrauterine growth restriction, by seeking mechanisms that involve genetic factors, utero-placental nutrient availability and vascular growth factors. New exciting findings on the genomic imprinting defects potentially associated with IUGR, and the placental anomalies associated with the decreased nutrient transport are summarized. Moreover, recent data on angiogenic growth factors as well as new information arising from application of gene chip technologies are discussed.     

Regulation of placental nutrient transport--a review

Fetal growth is primarily determined by nutrient availability, which is intimately related to placental nutrient transport. Detailed information on the regulation of placental nutrient transporters is therefore critical in order to understand the mechanisms underlying altered fetal growth and fetal programming. After briefly summarizing the cellular mechanisms for placental transport of glucose, amino acids and free fatty acids, we will discuss factors shown to regulate placental nutrient transporters and review the data describing how these factors are altered in pregnancy complications associated with abnormal fetal growth. We propose an integrated model of regulation of placental nutrient transport by maternal and placental factors in IUGR.     

Evaluation of maternal and umbilical serum TNFα levels in preeclamptic pregnancies in the intrauterine normal and growth-restricted fetus

Objective.?The aim of this study was to carry out a comparative analysis of the maternal and umbilical cord TNFα serum levels in pregnancies complicated by severe preeclampsia with normal intrauterine fetal growth, in preeclamptic pregnancies with intrauterine growth restriction (IUGR), and in normotensive pregnant patients.

Patients and methods.?The study was carried out on eight patients with severe preeclampsia complicated by IUGR and 18 preeclamptic patients with normal intrauterine fetal growth. The control group consisted of 18 healthy normotensive patients with singleton uncomplicated pregnancies. Maternal and umbilical serum TNFα concentrations were estimated using a sandwich ELISA assay.

Results and conclusions.?Pregnant women with severe preeclampsia had significantly higher maternal and umbilical serum TNFα levels than those in the normotensive controls. Our findings and other reports indicate that TNFα may participate in the pathogenesis and sequelae of preeclampsia with and without IUGR. The results of excessive umbilical serum activity of tumor necrosis factor α (TNFα) in preeclamptic pregnancy complicated by intrauterine growth restriction (IUGR) may suggest additional changes and dysfunction of the placental–fetal unit and deterioration of placental function, leading to fetal hypotrophia in the course of preeclampsia.