Origins of chromosome translocations in childhood leukaemia.

Chromosome translocations are often early or initiating events in leukaemogenesis, occurring prenatally in most cases of childhood leukaemia. Although these genetic changes are necessary, they are usually not sufficient to cause leukaemia. How, when and where do translocations arise? And can these insights aid our understanding of the natural history, pathogenesis and causes of leukaemia?

Developmental aspects of the pituitary-adrenal axis response to hemorrhagic stress in lamb fetuses in utero.

Plasma ACTH and corticosteroid concentrations were measured by radioimmunoassay in chronically catheterized fetuses of 32 pregnant sheep. Fetal plasma ACTH levels 38+/-5 pg/ml (means+/-SEM) were slightly (P < 0.05) lower than maternal 54+/-4 pg/ml levels. No general rise in fetal plasma ACTH concentration was noted before 140 days gestation; however, fetal plasma corticoid levels began to increase after about 125 days. This suggested that an increase in fetal adrenal responsiveness to endogenous ACTH occurred during gestation. Hemorrhage of 15% of estimated blood volume decreased mean arterial pressure from 54+/-3 to 36+/-3 torr and increased plasma ACTH from 30+/-5 to 130+/-30 pg/ml in fetuses older than 0.80 gestation. In fetuses younger than 0.67 gestation, 15% hemorrhage caused no change in plasma ACTH levels despite a significant fall in mean arterial pressure. This suggests that system(s) subserving the ACTH response to mild hemorrhage are either absent or nonfunctional in the younger fetuses. The hemorrhage-induced increase in plasma ACTH levels was associated with a small rise in plasma corticoids in fetuses younger than 0.94 gestation. In older fetuses, a similar increase in plasma ACTH was associated with a pronounced increase in plasma corticoid levels. This also suggests that an increase in adrenal responsiveness to endogenous ACTH occurs during gestation. No detectable changes in maternal plasma ACTH or corticoids were found in response to fetal hemorrhage, thus the fetal pituitary-adrenal axis can autonomously respond to stress.

Inactivation of the lysyl oxidase gene Lox leads to aortic aneurysms, cardiovascular dysfunction, and perinatal death in mice.

BACKGROUND: The lysyl oxidases are extracellular copper enzymes that initiate the crosslinking of collagens and elastin, 5 human isoenzymes having been characterized so far. The crosslinks formed provide the tensile strength and elastic properties for various extracellular matrices, including vascular walls. We studied the role of the first described isoenzyme Lox by inactivating its gene in mice. METHODS AND RESULTS: Murine Lox gene was disrupted by routine methods. Lox(-/-) mice died at the end of gestation or as neonates, necropsy of the live-born pups revealing large aortic aneurysms. In light microscopy, hazy and unruffled elastic lamellae in the Lox(-/-) aortas were observed, and electron microscopy of the aortic walls of the Lox(-/-) fetuses showed highly fragmented elastic fibers and discontinuity in the smooth muscle cell layers in Lox(-/-) fetuses. The wall of the aorta in the Lox(-/-) fetuses was significantly thicker, and the diameter of the aortic lumen was significantly smaller than that in the Lox(+/+) aortas. In Lox(-/-) fetuses, Doppler ultrasonography revealed increased impedance in the umbilical artery, descending aorta, and intracranial artery blood velocity waveforms, decreased mean velocities across cardiac inflow and outflow regions, and increased pulsatility in ductus venosus blood velocity waveforms. CONCLUSIONS: Lox has an essential role in the development and function of the cardiovascular system. Inactivation of the Lox gene causes structural alterations in the arterial walls, leading to abnormalities in the cardiovascular functions. Alterations in LOX activity may also play a critical role in certain human cardiovascular diseases.

Characteristics and outcomes of fetuses with pericardial effusions.

Little is known about the characteristics and outcomes of fetuses with pericardial effusions (PEs); therefore, this study sought to identify factors associated with fetal PEs and the natural histories and outcomes of fetuses with PEs. Large PEs are associated with a greater likelihood of structural heart disease, impaired cardiac function, and chromosomal abnormalities, and PEs with hydrops or extracardiac malformations are associated with death. Most fetal PEs resolve, and fetuses with isolated PEs have a very good prognosis.

Cardioprotective stress response in the human fetal heart.

OBJECTIVE: We propose that the fetal heart is highly resilient to hypoxic stress. Our objective was to elucidate the human fetal gene expression profile in response to simulated ischemia and reperfusion to identify molecular targets that account for the innate cardioprotection exhibited by the fetal phenotype. METHODS: Primary cultures of human fetal cardiac myocytes (gestational age, 15-20 weeks) were exposed to simulated ischemia and reperfusion in vitro by using a simulated ischemic buffer under anoxic conditions. Total RNA from treated and baseline cells were isolated, reverse transcribed, and labeled with Cy3 or Cy5 and hybridized to a human cDNA microarray for expression analysis. This analysis revealed a highly significant (false discovery rate, <3%) suppression of interleukin 6 transcript levels during the reperfusion phase confirmed by means of quantitative polymerase chain reaction (0.25 +/- 0.11-fold). Interleukin 6 signaling during ischemia and reperfusion was assessed at the protein expression level by means of Western measurements of interleukin 6 receptor, the signaling subunit of the interleukin 6 receptor complex (gp130), and signal transducer of activated transcription 3. Posttranslational changes in the protein kinase B signaling pathway were determined on the basis of the phosphorylation status of protein kinase B, mitogen-activated protein kinase, and glycogen synthase kinase 3beta. The effect of suppression of a prohypertrophic kinase, integrin-linked kinase, with short-interfering RNA was determined in an ischemia and reperfusion-stressed neonatal rat cardiac myocyte model. Endogenous secretion of interleukin 6 protein in culture supernatants was measured by enzyme-linked immunosorbent assay. RESULTS: Human fetal cardiac myocytes exhibited a significantly lower rate of apoptosis induction during ischemia and reperfusion and after exposure to staurosporine and recombinant interleukin 6 compared with that observed in neonatal rat cardiac myocytes ( P < .05 for all comparisons, analysis of variance). Exposure to exogenously added recombinant interleukin 6 increased the apoptotic rate in both rat and human fetal cardiac myocytes ( P < .05). Short-interfering RNA-mediated suppression of integrin-linked kinase, a prohypertrophy upstream kinase regulating protein kinase B and glycogen synthase kinase 3beta phosphorylation, was cytoprotective against ischemia and reperfusion-induced apoptosis in neonatal rat cardiac myocytes ( P < .05). CONCLUSIONS: Human fetal cardiac myocytes exhibit a uniquely adaptive transcriptional response to ischemia and reperfusion that is associated with an apoptosis-resistant phenotype. The stress-inducible fetal cardiac myocyte gene repertoire is a useful platform for identification of targets relevant to the mitigation of cardiac ischemic injury and highlights a novel avenue involving interleukin 6 modulation for preventing the cardiac myocyte injury associated with ischemia and reperfusion.

Perinatal hyperoxia for 14 days increases nerve conduction time and the acute unitary response to hypoxia of rat carotid body chemoreceptors.

Hyperoxia in the immediate perinatal period, but not in adult life, is associated with a life-long impairment of the ventilatory response to acute hypoxia. This effect is attributed to a functional impairment of peripheral chemoreceptors, including a reduction in the number of chemoreceptor afferent fibers and a reduction in "whole nerve" afferent activity. The purpose of the present study was to assess the activity levels of single chemoreceptor units in the immediate posthyperoxic period to determine whether functional impairment extended to single chemoreceptor units and whether the impairment was only induced by hyperoxia exposure in the immediate postnatal period. Two groups of rat pups were exposed to 60% inspired O2 fraction for 2 wk at ages 0-14 days and 14-28 days, at which time single-unit activities were isolated and recorded in vitro. Compared with control pups, hyperoxia-treated pups had a 10-fold reduction in baseline (normoxia) spiking activity. Peak unit responses to 12, 5, and 0% O2 were reduced and nerve conduction time was significantly slower in both hyperoxia-treated groups compared with control groups. We conclude that 1) hyperoxia greatly reduces single-unit chemoreceptor activities during normoxia and acute hypoxia, 2) the treatment effect is not limited to the immediate newborn period, and 3) at least part of the impairment may be due to changes in the afferent axonal excitability.

Genetic prenatal aqueductal stenosis with hydrocephalus in rat.

A recessive mutation which arose in Wistar albino rats was variably expressed in the homozygous state as prenatal stenosis of the aqueduct with resultant hydrocephalus. The condition was often compatible with survival to adulthood and with successful reproduction. Mildly sparse hair was the constant gene marker. Eye defects and sometimes foot deformities occurred. The first observable ultrastructural alteration was a disruption of the integrity of the neuroepithelial basal lamina in the cephalic neural tube of affected embryos as early as the 11th fetal day (16-24 somite pairs). The hydrocephalic syndrome closely resembled that produced by giving folic acid analogs to, or producing vitamin B12 deficiency in, pregnant rats in the period including the 11th day. Neither vitamin B12 nor folate, nor certain metabolites closely related to their metabolism, prevented the gene's expression. Homozygote mutants mated with homozygote mutants produced 70% hydrocephalic (dome-shaped heads) offspring, but if the mother was heterozygote, there was a "protective" effect and the number of hydrocephalic young was disproportionately smaller.

The neurodevelopmental basis of schizophrenia: clinical clues from cerebro-craniofacial dysmorphogenesis, and the roots of a lifetime trajectory of disease.

A "read-back" analysis of schizophrenia, from chronic illness, through the first psychotic episode, to psychosocial and neurointegrative abnormalities of childhood and infancy, leads to the intrauterine period as a primary focus for etiological events. Evidence for a characteristic topography of cerebro-craniofacial dysmorphology in schizophrenia is reviewed, and interpreted to estimate: (i) the timing of dysmorphic event(s); (ii) the nature of early cellular and molecular mechanisms which might determine that topography of dysmorphogenesis; and (iii) the population homogeneity of these processes. It is argued that early cerebro-craniofacial dysmorphogenesis in schizophrenia should be conceptualized as a first stage not in a static but rather in a dynamic, lifetime trajectory of disease.

In utero gene therapy: prospect and future.

Many genetic disorders are reported to cause irreversible damage to the fetus before birth. In utero gene therapy may be an effective tool for correction of genetic disorders by replacing defective gene with normal one. There are many reasons for moving forward with in utero gene therapy. The most important reason is to provide early intervention as to prevent or slow dysfunction and morbidity. This approach may prove to be advantageous in rapidly replicating fetal cells, and less sensitive to immune response to vector or transgene product due to underdeveloped immune system. In addition, the developing fetus may be a better candidate for gene therapy than the adult because gene engraftment may be more feasible in early fetal life, where stem cells or pleuripotent progenitor cells are more accessible to vectors. Some reports are available on successful in utero gene transfer in animal models but many questions remain to be answered before in utero gene therapy can be considered a viable solution to human. The real moral challenge facing in utero gene therapy is finding ways to insure that the review of protocols is adequate, and that those undertaking trials are competent to do so. Present review article analyzes the overall progress of the field, and the research that still needs to be performed before it can be considered to human clinical trials.

Diagnosis and outcome of dextrocardia diagnosed in the fetus.

A retrospective review of 5,539 fetal echocardiograms over a 22-year period revealed 85 cases of dextrocardia. In primary dextrocardia (46 cases), the incidence of situs solitus, inversus, and ambiguous, was similar and associated with a high incidence of complex cardiac malformations in situs solitus and situs ambiguous. Secondary dextrocardia (39 cases) was due to intrathoracic displacement and, when caused by diaphragmatic hernia, was associated with cardiac malformations in 31% of cases. Even in complex cases, fetal echocardiography was highly accurate; therefore, specific counseling can be given to parents.

Fetus in fetu: molecular analysis of a fetiform mass.

Fetus-in-fetu is a rare condition presenting as a calcified intra-abdominal mass in the newborn infant. Over 50 cases of fetus-in-fetu have been reported since 1800. Karyotype analysis in 8 cases and protein polymorphisms in 4 documented identical findings in the host and fetiform mass. We report a case of fetus-in-fetu in a newborn female including cytogenetic and molecular studies of both the host and mass. Genotypic information from 7 polymerase chain reaction (PCR) assays representing 4 chromosomes demonstrates heterozygous and identical alleles in the infant and fetus-in-fetu at all loci studied. A review of the literature is provided including a discussion regarding the impact of molecular data on present hypotheses of fetus-in-fetu pathogenesis.

Increased first trimester nuchal translucency as a prenatal manifestation of Smith-Lemli-Opitz syndrome.

Routine ultrasound examination at 11 weeks of gestation in a woman with no family history of genetic disease demonstrated increased accumulation of fluid in the fetal nuchal region. In view of the association of this defect with chromosomal abnormalities, fetal karyotyping was performed by chorion villus sampling and this demonstrated a normal 46,XY karyotype. Subsequent scans showed resolution of the nuchal fluid, and at the 20-week scan the fetal genitalia appeared to be female. Fetal blood sampling confirmed a normal male karyotype and fetoscopy confirmed the presence of female external genitalia. The parents elected to terminate the pregnancy, and postmortem findings were indicative of Smith-Lemli-Opitz syndrome. This was confirmed by the finding of increased levels of 7-dehydrocholesterol in cultured skin fibroblasts.

Prenatal sonographic diagnosis of hypochondroplasia in a high-risk fetus.

Hypochondroplasia (HCH) is caused by mutations in the fibroblast growth factor receptor type 3 (FGFR 3). Prenatal diagnosis of HCH based exclusively on the sonographic measurements of the fetal skeleton is difficult and has not been reported. We describe a newborn infant with HCH who was born to a mother with achondroplasia (ACH) and a father with HCH. Serial sonographic measurements were recorded from 16 weeks of gestation. All measurements remained normal up to 22 weeks of gestation. At 25 weeks of gestation, the long bones began to appear shorter than expected for gestational age, while the head measurements (biparietal diameter and head circumference) remained normal. The measurements were sufficiently different to distinguish from findings in normal and achondroplastic fetuses. Our findings suggest that it is possible to distinguish the normal fetus from a fetus affected with HCH and to distinguish HCH and ACH from each other based on the sonographic measurements alone. To our knowledge, this is the first report of longitudinal sonographic measurements of HCH in the second and third trimesters.

Prenatal diagnosis of Charcot-Marie-Tooth disease type 1A by multicolor in situ hybridization.

Genetic heterogeneity within the most common genetic neuropathy, Charcot-Marie-Tooth disease (CMT) results in about 70% slow nerve conduction CMT1 and 30% normal nerve conduction CMT2. Autosomal dominant CMT1A on chromosome 17p11.2 represents about 70% of CMT1 cases and about 50% of all CMT cases. Three different size CMT1A duplications with variable flanking breakpoints were characterized by multicolor in situ hybridization and confirmed by pulsed field gel electrophoresis and quantitative polymerase chain reaction (PCR) amplification. These different size duplications result in the same CMT1A phenotype confirming that trisomy of a normal gene region results in CMT1A. The smallest duplication does not include the 409 locus used previously to screen for CMT1A duplications. Direct analysis of interphase nuclei from fetuses and at-risk patients by multicolor in situ hybridization to a commonly duplicated CMT1A probe is informative more often than polymorphic PCR analysis, faster than pulsed field gel electrophoresis (PFGE), and faster, more informative, and more reliable than restriction enzyme analysis. CMT1B restriction enzyme analysis of CMT pedigrees without CMT1A is expected to diagnose another 8% of at-risk CMT1 patients (total: 78%).

B cell function after haploidentical in utero bone marrow transplantation in a patient with severe combined immunodeficiency.

An in utero paternal CD34(+) cell transplant was performed in a T-B+NK+ SCID fetus. We report here the results of the 3-year humoral immune reconstitution study. The methods used were ApoB VNTR typing, flow cytometry, nephelometry, hemagglutination, ELISA, ELISPOT and lymphoproliferative assays. The T cells were of donor origin whereas monocytes, B and NK cells were of host origin. Peripheral B cell counts and IgM levels were normal since birth. IVIG therapy was required at 5 months of age until 2 years old. IgA levels > or =20 mg/dl were detected from month 17 post transplantation. Isohemagglutinins were present since month 8 post transplantation, the highest titers (anti-A:1/128, anti-B:1/32) were obtained at month 33 post-transplantation. After immunization with rHBsAg, circulating anti-HBsAg IgG secreting cells and a 7.8-fold increase in serum anti-HBsAg Ab were detected. We conclude that split chimerism following in utero haploidentical BMT allows complete humoral immune reconstitution in a T-B+NK+ SCID patient.

Late gestation modulation of fetal glucocorticoid effects requires the receptor for leukemia inhibitory factor: an observational study.

BACKGROUND: Ablation of the low-affinity receptor subunit for leukemia inhibitory factor (LIFR) causes multi-systemic defects in the late gestation fetus. Because corticosterone is known to have a broad range of effects and LIF function has been associated with the hypothalamo-pituitary-adrenal axis, this study was designed to determine the role for LIFR in the fetus when exposed to the elevated maternal glucocorticoid levels of late gestation. Uncovering a requirement for LIFR in appropriate glucocorticoid response will further understanding of control of glucocorticoid function. METHODS: Maternal adrenalectomy or RU486 administration were used to determine the impact of the maternal glucocorticoid surge on fetal development in the absence of LIFR. The mice were analyzed by a variety of histological techniques including immunolabeling and staining techniques (hematoxylin and eosin, Alizarin red S and alcian blue). Plasma corticosterone was assayed using radioimmunoassay. RESULTS: Maternal adrenalectomy does not improve the prognosis for LIFR null pups and exacerbates the effects of LIFR loss. RU486 noticeably improves many of the tissues affected by LIFR loss: bone density, skeletal muscle integrity and glial cell formation. LIFR null pups exposed during late gestation to RU486 in utero survive natural delivery, unlike LIFR null pups from untreated litters. But RU486 treated LIFR null pups succumb within the first day after birth, presumably due to neural deficit resulting in an inability to suckle. CONCLUSION: LIFR plays an integral role in modulating the fetal response to elevated maternal glucocorticoids during late gestation. This role is likely to be mediated through the glucocorticoid receptor and has implications for adult homeostasis as a direct tie between immune, neural and hormone function.

Histology of fetal eyes with oculocutaneous albinism.

The diagnosis of tyrosinase-negative oculocutaneous albinism (OCA) was made in a 19-week-old fetus by skin biopsy. Because the parents had an 11-year-old son with tyrosinase-negative OCA, they requested that the fetus be aborted at the 20th week of gestation. A histological analysis of the eyes was performed. Throughout the retina, the ganglion cell layer was separated from the inner neuroblastic layer by the inner plexiform layer. However, the number of ganglion cells was decreased and the nerve fiber layer was immature. Bipolar and horizontal cells had begun to segregate into the inner nuclear layer. Rods and cones were identifiable in the posterior, but not peripheral, retina. Cones were more numerous in the center of the retina, and no rod-free area was identifiable. In addition, the ciliary body (epithelial folds, blood vessels in the mesodermal connective tissue core, and ciliary muscle) was less developed than in a normal fetus. Melanosomes in the retinal pigment epithelium only contained filaments without melanization and were therefore classified as stage I or II melanosomes. However, the ciliary epithelium also contained some stage III melanosomes with melanin adherent to the filaments.

Intrapericardial foregut cyst associated with intrauterine death.

Intrapericardial developmental foregut cysts are rare and are most frequently incidental findings at necropsy in adults. A 29 year old Asian woman delivered a 24 week stillborn fetus seven days after diagnosis of intrauterine death caused by rupture of a foregut cyst. Multiple cysts occupied the wall of the right atrium and its rupture caused haemopericardium and cardiac tamponade.

Outcome of twin gestations after first trimester chorionic villus sampling.

OBJECTIVE: To tabulate genetic results and obstetric outcomes of twin pregnancies after first-trimester chorionic villus sampling (CVS). METHODS: The study included 262 consecutive women with twin pregnancies who had first-trimester CVS between 1988 and 1998. RESULTS: Major indications for prenatal diagnosis included maternal age (n = 82), pregnancies after intracytoplasmic sperm injection (n = 114), or both (n = 33). Among 524 fetuses, 519 were sampled adequately. Cytogenetic results were incorrect because of sampling the same fetus twice in two pregnancies. In three pregnancies, contamination caused by mixed sampling made cytogenetic results uncertain. Correct genetic diagnoses were obtained in 509 fetuses, 24 of which had chromosomal abnormalities on direct preparations and four of which had monogenetic conditions. Additional invasive procedures were done on five occasions. Fifteen fetuses were terminated selectively. The total fetal loss rate was 5.5% (28 of 509). The indication for the procedure did not significantly determine the fetal loss rate. The mean +/- standard deviation (SD) gestational age at birth was 35.9 +/- 2.9 weeks, and the mean +/- SD birth weights for twins A and B were 2429 +/- 589.1 g and 2378 +/- 588.5 g, respectively. CONCLUSION: First-trimester CVS is an accurate means of prenatal genetic diagnosis in twins, offering early selective termination in cases of abnormal genetic results in one of the fetuses.

Natural evolution of nuchal thickness in trisomy-21 fetuses.

OBJECTIVE: To assess the natural evolution of nuchal thickness in trisomy-21 fetuses. METHODS: Serial measurements of nuchal thickness were performed over a 1- to 6-week period in 45 consecutive fetuses with trisomy 21, between the 10th and the 23rd weeks of pregnancy. To avoid a gestational age confounding effect, nuchal thickness also was expressed in standard deviations (SDs) for the corresponding gestational week. In addition, the changes were assessed in terms of the presence of clinical positive thickening, considered as such when the measurement was above 2.5 SD. RESULTS: A mean increase of 1.8 mm (95% confidence interval [CI] 1.3, 2.3) for nuchal thickness was observed for a mean period of 21 days. When corrected by gestational age, the mean increase of 0.3 SD (95% CI -0.2, 0.9) was found to be not significant. No clinically relevant nuchal thickening changes were recorded (51% versus 69%) at re-examination. CONCLUSION: Nuchal thickening at re-examination is observed in a similar proportion of trisomy-21 fetuses as when first observed.