First trimester three-dimensional transvaginal imaging of alobar holoprosencephaly associated with proboscis and hypotelorism (ethmocephaly) in a 46,XX fetus

Transitory and Vestigial Structures of the Developing Human Nervous System

As with many body organs, the human central nervous system contains many structures and cavities that may have had functions in embryonic and fetal life but are vestigial or atrophic at maturity. Examples are the septum pellucidum, remnants of the lamina terminalis, Cajal-Retzius neurons, induseum griseum, habenula, and accessory olfactory bulb. Other structures are transitory in fetal or early postnatal life, disappearing from the mature brain. Examples are the neural crest, subpial granular glial layer of Brun over cerebral cortex, radial glial cells, and subplate zone of cerebral cortex. At times persistent fetal structures that do not regress may cause neurological problems or indicate a pathologic condition, such as Blake pouch cyst. Transitory structures thus can become vestigial. Examples are an excessively wide cavum septi pellucidi, suprapineal recess of the third ventricle, trigeminal artery of the posterior fossa circulation, and hyaloid ocular artery. Arrested maturation might be considered another aspect of vestigial structure. An example is the persistent microcolumnar cortical architecture in focal cortical dysplasia type Ia, in cortical zones of chronic fetal ischemia, and in some metabolic/genetic congenital encephalopathies. Some transitory structures in human brain are normal adult structures in lower vertebrates. Recognition of transitory and vestigial structures by fetal or postnatal neuroimaging and neuropathologically enables better understanding of cerebral ontogenesis and avoids misinterpretations.

Correlations Between Phenotypes and Biological Process Ontologies in Monogenic Human Diseases

A substantial body of research is focused to improve the understanding of the relationship between genotypes and phenotypes. Genotype-phenotype studies have shown promise in improving disease diagnosis in humans and identification of specific clinical phenotypes may be helpful in developing more effective therapeutic and diagnostic strategies. To expand on the existing paradigm of evaluating genotypes and phenotypes, we present an investigation of the correlation between biological processes as represented by genomic information and phenotypes in human disease. We focus on monogenic diseases and link biological process and phenotype utilizing information from the Online Mendelian Inheritance in Man, the Gene Ontology, and the Human Phenotype Ontology comprehensive genomic, phenotypic, and disease information resources. Our study uncovers 4661 statistically significant associations and identifies novel correlations between biological processes and phenotypes. We find new relationships between unique phenotype-genotype pairs related to cardiovascular diseases and hypertelorism, which suggests that differences between certain phenotype-genotype association may be the key to the divergence of corresponding phenotypes. Although the application of correlating genotype, phenotype, and biological processes may help to guide diagnosis and treatment of diseases, further investigation and more specific gene ontology descriptions are still required to elucidate mechanisms of action.

Typical changes of ethmocephaly and holoprosencephaly in a fetus at 14 weeks of gestation

Background

This case report is to show the details of the face of a very rare ethmocephaly at 14 weeks of gestation.

Case presentation

After the regular transabdominal two-dimensional (2D) scan for nuchal translucency we could describe the following malformations: holoprosencephaly, proboscis and an abnormal face, omphalocele containing bowel, hyperechoic kidneys and megacystis. In addition, we acquired transvaginal three-dimensional (3D) ultrasound volume blocks of the fetal head, scanned with different insonation angles and stored them for later analysis. Using the multiplanar mode the volume blocks taken from the front show all details of the face: proboscis, hypotelorism, microphthalmia, cleft palate, accelerated development of the frontal bones and premature closure of the metopic suture. The volume blocks taken through the squamosal suture show all details of the fossa posterior and brain: fused thalami surrounded by the typical monoventricle, normal brain stem, elongation of anterior membranous area. Render mode shows a precise 3D image of the face. To better demonstrate the changes of the fetal face a post-mortem photo of the fetal face is included.

Conclusion

This case report can demonstarte the typical changes of ethmocephaly in the first trimester using transvaginal 3D scan.

Cyclopia: a rare condition with unusual presentation - a case report

INTRODUCTION

Cyclopia (alobar holoprosencephaly) (OMIM% 236100) is a rare and lethal complex human malformation, resulting from incomplete cleavage of prosencephalon into right and left hemispheres occurring between the 18th and the 28th day of gestation. Holoprosencephaly occurs in 1/16,000 live births, and 1/250 during embryogenesis. Approximately 1.05 in 100,000 births are identified as infants with cyclopia, including stillbirths. Cyclopia typically presents with a median single eye or a partially divided eye in a single orbit, absent nose, and a proboscis above the eye. Extracranial malformations described in stillbirths with cyclopia include polydactyl, renal dysplasia, and an omphalocele. The etiology of this rare syndrome, which is incompatible with life, is still largely unknown. Most cases are sporadic. Heterogeneous risk factors have been implicated as possible causes.

CASE PRESENTATION

A live full-term baby with birth weight of 2900 g, product of cesarean section because of severe fetal bradycardia, was born at Prince Hashem Military Hospital – Zarqa city/Jordan. This newborn was the first baby to a non-consanguineous family, and a healthy 18-year-old mother, with no history of drug ingestion or febrile illnesses during pregnancy. Antenatal history revealed severe hydrocephalus diagnosed early by intrauterine ultrasound but the pregnancy was not terminated because of the lack of medical legitimization in the country. On examination, the newborn was found to have a dysmorphic face, with a median single eye, absence of nose, micrognathia, and a proboscis above the eye, all of which made cyclopia the possible initial diagnosis. Multiple unusual abdominal defects were present that include a huge omphalocele containing whole liver and spleen, urinary bladder extrophy, and undefined abnormal external genitalia, which called for urgent confirmation. Brain MRI was done and revealed findings consistent with alobar holoprosencephaly (cyclopia).

CONCLUSION

Presentation of cyclopia is not fully exposed and new cyclopian syndromes still can appear. The prenatal diagnosis of cyclopia can be made early by ultrasound, and the awareness of the spectrum of sonographic findings of cyclopia can improve the accuracy of prenatal diagnosis. The legitimization of pregnancy termination for indexed cases in many countries around the world should be revised.

Precocious synapses in 13.5-week fetal holoprosencephalic cortex and cyclopean retina

BACKGROUND

Genetic programming of cerebral development involves tissue morphogenesis and also timing of developmental processes. Precocious synaptogenesis in the neocortical plate was previously demonstrated in 5 of 6 fetuses of 20-31 weeks gestation.

MATERIALS AND METHODS

Neuropathological examination was performed of a 13-week-5-day fetus with trisomy-13, a lobar holoprosencephaly, hydrocephalus, cyclopia and absence of ears. Immunocytochemical demonstration of the synaptic vesicle protein synaptophysin was performed in the brain and retina, along with other neuronal markers.

RESULTS

Synaptophysin reactivity in the cortical plate was patchy and precocious. Radial glial fibres, demonstrated by vimentin, were oriented parallel to the cortical plate rather than perpendicular, probably because of hydrocephalus. A corpus striatum was not identified, but the poorly formed thalamus exhibited synaptophysin reactivity around many neurones. The cyclopean eye had ocular features of maturational delay including persistent hyaloid artery; ganglion cells were reduced in number, but retinal synaptophysin reactivity was paradoxically precocious.

CONCLUSIONS

Holoprosencephaly exhibits abnormal patchy synapse distribution in the neocortex and retina; synaptogenesis was precocious, as we previously described in older fetuses. Too soon an onset of synapse formation may promote early epileptic circuitry, leading to severe infantile epilepsies postnatally. The visual system is the last of the special sensory systems to mature, yet in this case showed too early synapse formation. In HPE, cyclopia and in trisomy 13, total absence of external ears has not been reported; it results from faulty craniofacial induction by neural crest.

Neurosonoembryology by three-dimensional ultrasound

High-resolution three-dimensional (3D) ultrasound has enabled the visualization of small embryos and fetuses, and embryology in vivo - '3D sonoembryology' - has been established based on conventional embryology. Recently developed imaging techniques allow the definition of in-vivo anatomy including visualization of the embryonic circulation and dynamic features that could not be characterized in fixed specimens. Three-dimensional ultrasound has facilitated increasingly accurate and objective prenatal diagnoses of cranium bifidum/spina bifida, holoprosencephaly and associated anomalies in the first trimester and may allow detection of pathologic central nervous system (CNS) development at an earlier gestational age. It may be no exaggeration to suggest that prenatal diagnoses of fetal abnormalities have shifted from second to first trimester. However, fetal brain develops rapidly in the second trimester, therefore early scanning covers only selected CNS anomalies described in this article and serial continuous observation in the second trimester will be required.

First trimester ultrasound: current approaches and practical pitfalls

Revolutionary technological improvements and high-frequency transvaginal scanning have enabled the resolution of ultrasound imaging in the first trimester to increase such that detailed early fetal development can now be well visualized. This investment in imaging technology has enabled not only normal embryonic development but also chromosomal abnormalities and structural anomalies to be more easily and accurately diagnosed before the second trimester. This article is intended to help radiologists in the interpretation and clinical application of normal and abnormal first trimester ultrasound findings in early pregnancy. We review the current literature and applications and interpretations of first trimester ultrasound.

Semilobar holoprosencephaly with associated cyclopia and radial aplasia: first trimester diagnosis by means of integrating 2D-3D ultrasound

INTRODUCTION

Holoprosencephaly (HPE) is commonly associated with facial malformations. We present a case of semilobar HPE associated with distal limb defect which was detected at 12 weeks of gestation.

CASE

The fetus had a crown-rump length of 60 mm (12 weeks-4 days), had nuchal translucency thickness of 1.5 mm. Initial two-dimensional (2D) ultrasound revealed the absence of nasal bone, decreased BPD and abnormal profile. Transvaginal 2D ultrasound was effective in the detection of HPE (partially absence of the interhemispheric fissure, fused thalami, the choroid plexuses were not visualized bilateraly: absent 'butterfly' sign), cylopia, absence of the nose and unilateral radial aplasia. Three dimensional (3D) ultrasound provided a better visualization of the associated anomalies. The necropsy result confirmed the sonographic findings: the diagnosis was semilobar HPE, cyclopia, absence of the nose, and the absence of the radius and the thumb in the left arm.

DISCUSSION

Transvaginal 2D sonographic examination is effective in detection of the cases with HPE at first trimester. Fetal morphological study through 3D ultrasound may facilitate the diagnosis of associated anomalies.