The developmental biology of genetic Notch disorders.

Notch signaling regulates a vast array of crucial developmental processes. It is therefore not surprising that mutations in genes encoding Notch receptors or ligands lead to a variety of congenital disorders in humans. For example, loss of function of Notch results in Adams-Oliver syndrome, Alagille syndrome, spondylocostal dysostosis and congenital heart disorders, while Notch gain of function results in Hajdu-Cheney syndrome, serpentine fibula polycystic kidney syndrome, infantile myofibromatosis and lateral meningocele syndrome. Furthermore, structure-abrogating mutations in NOTCH3 result in CADASIL. Here, we discuss these human congenital disorders in the context of known roles for Notch signaling during development. Drawing on recent analyses by the exome aggregation consortium (EXAC) and on recent studies of Notch signaling in model organisms, we further highlight additional Notch receptors or ligands that are likely to be involved in human genetic diseases.

Prenatal diagnosis of caudal regression with heterotaxy syndrome: "A mermaid with a broken heart".

Caudal regression syndrome (CRS) is a rare congenital malformation with varying degrees of early gestational developmental failure. It is characterized by agenesis of the sacrum and lumbar spine, with lower limb neurological deficit and accompanying deformities of the pelvis, lower extremities, genitourinary, and gastrointestinal systems. We report a case of CRS associated with rare complex congenital heart defect, that is, heterotaxy syndrome, diagnosed prenatally.

Traffic jam in the primitive streak: the role of defective mesoderm migration in birth defects.

Gastrulation is the process in which the three germ layers are formed that contribute to the formation of all major tissues in the developing embryo. We here review mouse genetic models in which defective gastrulation leads to mesoderm insufficiencies in the embryo. Depending on severity of the abnormalities, the outcomes range from incompatible with embryonic survival to structural birth defects, such as heart defects, spina bifida, or caudal dysgenesis. The combined evidence from the mutant models supports the notion that these congenital anomalies can originate from perturbations of mesoderm specification, epithelial-mesenchymal transition, and mesodermal cell migration. Knowledge about the molecular pathways involved may help to improve strategies for the prevention of major structural birth defects.

Encephalocystocele - uncommon diagnosis in prenatal medicine.

Encephalocystocele is a developmental malformation characterized by brain herniation accompanied with extracranial cystic protrusion of the ventricular system. This nosological unit is often overlooked and insufficiently classified merely as encephalocele. Herein, two exceptionally clear cases of the parieto-occipital cranioschisis with encephalocystocele and congenital hydrocephalus of the lateral ventricles are documented with 2-dimensional/3-dimensional sonographic images and the corresponding MRI findings. In both cases, prenatal diagnosis was confirmed by autopsy.

[Cervical meningocele with filiform connection. Case report]. / Meningocele cervical con conexión filiforme. Reporte de un caso.

The meningocele is the least common form of spina bifida cystica and represents less than 10% of cases of this disorder. A case of a female patient aged 26 with a history of two pregnancies and two previous cesarean sections, present pregnancy unplanned, uncontrolled during the first trimester prenatal and without supplementation with folic acid. Family history of consanguinity with her husband (second cousins) and psychomotor reassessed in four maternal cousins. The first follow-up visit the patient was at 34 weeks of pregnancy. The ultrasonographic findings were: cervical meningocele posterior filiform connection between the first and second cervical vertebrae, lateral ventriculomegaly and third and fourth ventricles and hydrocephalus secondary. Cesarean section was performed at 37 weeks gestation and was a newborn male 3.000 g, 52 cm, head circumference of 36 cm, Apgar 8/9, Capurro 37 weeks of gestation. In the posterior cervical region tumor was located a soft 5 x 5 cm with intact skin, adhered to deep planes. Movement of all four extremities without neurological involvement. He referred to the department of neurosurgery for shunt placement and subsequently performed surgical excision of the meningocele.

[Progress in the prenatal treatment and anesthetic considerations for fetal surgery].

Recent advances in prenatal diagnosis have made fetal surgery as a possible treatment for a wide variety of fetal diseases. Fetal surgeries consist of minimally invasive fetal surgery such as ultrasound guided procedure and fetoscopic surgery, open fetal surgery, and ex-utero intrapartum treatment. Effectiveness of these fetal surgeries has been discussed and proved to be effective for some diseases. If a fetal surgery is planned, an anesthesiologist is required to offer optimal anesthesia both for mother and fetus. For this purpose, anesthesiologists are supposed to know outlines of the fetal treatment in addition to pediatric and obstetric anesthesia, as a member of multidisciplinary team. In this review, outlines of fetal treatment will be introduced and anesthetic considerations for fetal surgeries will be discussed.

[Tumoral degeneration occurring over a non-healing meningocele. Report of two cases]. / Degeneración tumoral en meningocele no intervenido. Descripción de dos casos.

A giant meningocelic sac has not been usually described in adult patients, due to the fact that it shows a low incidence and few newborn have survived to date though the malformation is benign. We report two cases of patients born with the described malformation and who were not operated at that time, so they reached adulthood with bigger sacs. They needed surgery to remove the sacs, for a different reason. The older one had a fistulous abcess but the LCR did not come out, and it did not improved by the application of topic and antibiotic treatment. The other patient showed a progressive growth of the malformation during the last year, skin hardening and pain. The histological study of the dried sacs proved the existence of a carcinomatous degeneration. In the patients we have treated, it seems that a chronic irritation of the LCR and the appearance of multipotent cells in the meningocele may favour the malignancy of the tissues surrounding the sac. This possible malignancy, already described in the bibliography, suggests a prompt elective surgical treatment of the patients with these congenital lesions as soon as possible.

Evidence for multi-site closure of the neural tube in humans.

Four separate initiation sites for neural tube (NT) fusion have been demonstrated recently in mice and other experimental animals. We evaluated the question of whether the multisite model vs. the traditional single-site model of NT closure provided the best explanation for neural tube defects (NTDs) in humans. Evidence for segmental vs. continuous NT closure was obtained by review of our recent clinical cases of NTDs and previous medical literature. With the multi-site NT closure model, we find that the majority of NTDs can be explained by failure of fusion of one of the closures or their contiguous neuropores. We hypothesize that: Anencephaly results from failure of closure 2 for meroacranium and closures 2 and 4 for holoacranium. Spina-bifida cystica results from failure of rostral and/or caudal closure 1 fusion. Craniorachischisis results from failure of closures 2, 4, and 1. Closure 3 non-fusion is rare, presenting as a midfacial cleft extending from the upper lip through the frontal area ("facioschisis"). Frontal and parietal cephaloceles occur at the sites of the junctions of the cranial closures 3-2 and 2-4 (the prosencephalic and mesencephalic neuropores). Occipital cephaloceles result from incomplete membrane fusion of closure 4. In humans, the most caudal NT may have a 5th closure site involving L2 to S2. Closure below S2 is by secondary neurulation. Evidence for multi-site NT closure is apparent in clinical cases of NTDs, as well as in previous epidemiological studies, empiric recurrence risk studies, and pathological studies. Genetic variations of NT closures sites occur in mice and are evident in humans, e.g., familial NTDs with Sikh heritage (closure 4 and rostral 1), Meckel-Gruber syndrome (closure 4), and Walker-Warburg syndrome (2-4 neuropore, closure 4). Environmental and teratogenic exposures frequently affect specific closure sites, e.g., folate deficiency (closures 2, 4, and caudal 1) and valproic acid (closure 5 and canalization). Classification of NTDs by closure site is recommended for all studies of NTDs in humans.(ABSTRACT TRUNCATED AT 400 WORDS)

Myelomeningocele before birth.

The authors report a study of 92 human embryos and four fetuses with myeloschisis. The characteristics of embryonic myeloschisis compared with spina bifida cystica in infants are: 1) the lesion is often more diffuse, involving the whole spinal cord (12 embryos); 2) the cervical cord is frequently affected (23 of the remaining 80 embryos); 3) holoprosencephaly is frequently associated (18 embryos); 4) meningocele is not found; and 5) hydrocephalus and Arnold-Chiari malformation are not yet developed. Hydrocephalus and Arnold-Chiari malformation are found in myeloschistic fetuses. Almost all embryos with diffuse and cervical myeloschisis or with holoprosencephaly are extruded before birth by spontaneous abortion. Absence of meningocele in the embryonic period implies that its appearance is deferred to the fetal period. The development of hydrocephalus and Arnold-Chiari malformation also seems to be delayed until the fetal period. Our observation implies that myelomeningocele is induced by non-closure of the neural tube, not by rupture once it was closed. "Neural overgrowth" and disturbed "recanalization process" are discussed in relation to the pathogenesis of myelomeningocele.

The nature of congenital posterior cervical or cervicothoracic midline cutaneous mass lesions. Report of eight cases.

Between 4% and 8% of cases of spina bifida cystica occur in a cervical or cervicothoracic location. Despite a large body of literature concerning spinal dysraphism, there has been little written specifically about patients afflicted with this disorder in a cervical location. Eight children who presented at birth with posterior cervical or cervicothoracic lumps, all of which represented a dysraphic state, are discussed. Two types of abnormalities were noted. Three patients had hydromyelia with an associated myelocystocele herniating posteriorly into a meningocele sac. In these three patients there was an associated Chiari II malformation and hydrocephalus. The other five children had a meningocele in which a band of tissue extended from the posterior aspect of the spinal cord through a defect in the bone and fascia to the posterior part of the meningocele sac itself. No patient had a lesion that could be described as a meningomyelocele. The investigation and surgical management of these conditions are discussed and the need for intradural exploration to untether the spinal cord in the cervical region is stressed.

Neurocutaneous melanosis associated with Dandy-Walker malformation and a meningohydroencephalocele. Case report.

Neurocutaneous melanosis and Dandy-Walker malformation are both forms of rare congenital neurodysplasia. Interestingly, 8 to 10% of patients with neurocutaneous melanosis also harbor an associated Dandy-Walker malformation, indicating that these developmental abnormalities share a common origin. The authors describe a case of neurocutaneous melanosis associated with Dandy-Walker malformation and an occipital meningohydroencephalocele with a giant melanotic nevus. Multiple congenital liver masses were also observed in the infant. The occipital nevus was totally excised, and ventriculoperitoneal and cyst-peritoneal shunts were created to prevent subsequent hydrocephalus. Findings in this case support the possibility that excessive melanocytes hinder normal mesenchymal development, causing Dandy-Walker malformation and an occipital meningocele.

Orally administered melatonin prevents lipopolysaccharide-induced neural tube defects in mice.

Lipopolysaccharide (LPS) has been associated with adverse pregnant outcomes, including fetal demise, intra-uterine growth restriction (IUGR), neural tube defects (NTDs) and preterm delivery in rodent animals. Previous studies demonstrated that melatonin protected against LPS-induced fetal demise, IUGR and preterm delivery. The aim of the present study was to investigate the effects of melatonin on LPS-induced NTDs. All pregnant mice except controls were intraperitoneally injected with LPS (25 µg/kg) daily from gestational day (GD)8 to GD12. Some pregnant mice were orally administered with melatonin (MT, 50 mg/kg) before each LPS injection. A five-day LPS injection resulted in 27.5% of fetuses with anencephaly, exencephaly or encephalomeningocele. Additional experiment showed that maternal LPS exposure significantly down-regulated placental proton-coupled folate transporter (pcft) and disturbed folate transport from maternal circulation through the placentas into the fetus. Interestingly, melatonin significantly attenuated LPS-induced down-regulation of placental pcft. Moreover, melatonin markedly improved the transport of folate from maternal circulation through the placentas into the fetus. Correspondingly, orally administered melatonin reduced the incidence of LPS-induced anencephaly, exencephaly or encephalomeningocele. Taken together, these results suggest that orally administered melatonin prevents LPS-induced NTDs through alleviating LPS-induced disturbance of folate transport from maternal circulation through the placenta into the fetus.

Meningocele following aplasia of the occipital bone.

We describe a first trimester female foetus with aplasia of the occipital bone allowing a meningocele without skin coverage to be formed. The pregnancy was terminated, and on later autopsy the brain appeared to be intact. The foetus carried an apparently balanced translocation 46,XX,t(3;9)(p21.3;q22.3) inherited from a normal father and grandfather.

Prenatal screening and diagnosis of neural tube defects.

This review article discusses prenatal screening and diagnosis of neural tube defects (NTD). High detection rates occur in countries operating ultrasound screening programmes because classical two-dimensional ultrasound cranial signs (lemon shaped head, banana cerebellum, ventriculomegaly) are important diagnostic clues to the presence of spina bifida. Careful evaluation of both the spine and a search for other abnormalities is warranted. Important prognostic information for spina bifida relates to the lesion level, with a "watershed" between L3 and L4 marking a very high chance of being wheelchair bound with the higher lesions. Three-dimensional ultrasound using multiplanar views can achieve diagnostic accuracy within one vertebral body in around 80% of patients. There are high rates of pregnancy termination for spina bifida in many European countries, but the use of new imagining techniques allow better prediction of outcome, and consequently a refinement of prenatal counselling.

Lateral meningocele and defect of abdominal wall.

A case of lateral meningocele associated with deficiency of the thoraco-abdominal wall is reported. It is suggested that both of these defects are due to interference with the development of the paraxial mesoderm by a single injury.

[The effect of a parietal meningoencephalocele on the morphogenesis of the neuroepithelium of the human brain]. / Vliianie temennoi meningoéntsefalotsel'noi gryzhi na morfogenez neiroépiteliia golovnogo mozga cheloveka.

Meningoencephalic hernia was studied in human embryo at the 5th week (stage 15) of the development. The analysis of parietal hernia showed that the anomalous development of cerebral tissue was related with disturbed shape-forming processes in the nerve tube. The medullar toruli were not closed at the stage of nerve plate to form a free edge of neuroepithelial layer. Its relaxation resulted in a spontaneous foldness and an enhanced proliferation of neuroepithelial cells. The proliferative activity induced hyperplasia of the layer end zones a disproportionately rapid growth of the brain disturbed the integrity of cephalic ectoderm and elicited formation of external cerebral hernias. It was suggested that disturbances of tangential mechanical tensions which control the proliferative activity in the neuroepithelium underlie the overgrowth of nervous tissue.

[Vesico-intestinal fissure with meningocystocele--attempt at clarifying an embryologic connection]. / Vesico-intestinale Spalte mit Meningocystocele--Versuch der Klärung eines embryologischen Zusammenhangs.

The treatment of a boy is reported, who suffered from a combination of vesico-intestinal fissure and meningocystocele. Because five of seven patients known to us since 1969 had a similar combination, it should be analysed whether there exists an etiological or embryological connection. Therefore the pertinent literature and clinical data of known patients was collected and evaluated. It can be shown that also in the literature a coincidence of 75% of vesico-intestinal fissure and meningomyelocele is reported and both are caused during the 4th week of embryological development. Vesico-intestinal fissure is a disturbance of mesodermal inflow into the lower abdominal wall. The cause for meningocystocele is an abnormal cell proliferation of the neural anlage. Despite a number of possible clues an etiological connection could not be proved.

Cervical meningoceles and myelocystoceles: a unifying hypothesis.

The classification and embryogenesis of cystic cervical dysraphic lesions are discussed in the light of the authors' experience and review of the literature. It is felt that these lesions are best described as meningoceles or myelocystoceles, and the use of the term 'myelomeningocele' may be more confusing than clarifying. The authors hypothesize that the cervical meningocele and the myelocystocele are part of a spectrum of the same underlying developmental abnormality, namely limited dorsal myeloschisis, with the eventual abnormality depending on the presence or absence of associated hydromyelia.