1/67. Heterotaxy-neural tube defect and holoprosencephaly occuring independently in two sib fetuses.We report on two sib fetuses, products of a consanguineous union, who had multiple and apparently unrelated malformations. The first fetus, a female, had trilobed lungs, a single cardiac ventricle, asplenia, situs ambiguus of the liver, and a lumbosacral meningomyelocele. The brain of this fetus was normal. The second fetus, a male, had bilobed lungs, a single cardiac ventricle, situs solitus of the abdominal organs and spleen, and a semilobar holoprosencephaly. The occurrence of these malformations in sibs of different sexes and the parental consanguinity suggest a recessive mutation in a gene responsible for both heterotaxy and midline defects, including holoprosencephaly.- - - - - - - - - - ranking = 1keywords = brain (Clic here for more details about this article) |
2/67. Mutations in the homeodomain of the human SIX3 gene cause holoprosencephaly.holoprosencephaly (HPE) is a common, severe malformation of the brain that involves separation of the central nervous system into left and right halves. Mild HPE can consist of signs such as a single central incisor, hypotelorism, microcephaly, or other craniofacial findings that can be present with or without associated brain malformations. The aetiology of HPE is extremely heterogeneous, with the proposed participation of a minimum of 12 HPE-associated genetic loci as well as the causal involvement of specific teratogens acting at the earliest stages of neurulation. The HPE2 locus was recently characterized as a 1-Mb interval on human chromosome 2p21 that contained a gene associated with HPE. A minimal critical region was defined by a set of six overlapping deletions and three clustered translocations in HPE patients. We describe here the isolation and characterization of the human homeobox-containing SIX3 gene from the HPE2 minimal critical region (MCR). We show that at least 2 of the HPE-associated translocation breakpoints in 2p21 are less than 200 kb from the 5' end of SIX3. Mutational analysis has identified four different mutations in the homeodomain of SIX3 that are predicted to interfere with transcriptional activation and are associated with HPE. We propose that SIX3 is the HPE2 gene, essential for the development of the anterior neural plate and eye in humans.- - - - - - - - - - ranking = 2.9667870829071keywords = brain, central nervous system, nervous system (Clic here for more details about this article) |
3/67. Unusually prolonged survival and childhood-onset epilepsy in a case of alobar holoprosencephaly.Alobar holoprosencephaly is one of the most severe congenital malformations of the central nervous system. Most affected infants are stillborn or have a very short life-span. The survivors can present with neonatal seizures and/or infantile spasms. We report on an unusually long-lived patient with alobar holoprosencephaly and minor facial dysmorphism, who developed generalized epilepsy during childhood.- - - - - - - - - - ranking = 0.96678708290715keywords = central nervous system, nervous system (Clic here for more details about this article) |
4/67. prenatal diagnosis of partial trisomy 3p(3p23-->pter) and monosomy 7q(7q36-->qter) in a fetus with microcephaly alobar holoprosencephaly and cyclopia.We report the prenatal diagnosis of partial trisomy 3p(3p23-->pter) and monosomy 7q(7q36-->qter) in a fetus with microcephaly, alobar holoprosencephaly and cyclopia. A 26-year-old primigravida woman was referred for genetic counselling at 23 gestational weeks due to sonographic findings of intra-uterine growth retardation and cranio-facial abnormalities. Level II ultrasonograms further demonstrated alobar holoprosencephaly, a proboscis above the eye and a single median orbit consistent with cyclopia. Genetic analysis and fluorescence in situ hybridization on cells obtained from amniocentesis showed distal 3p trisomy (3p23-->pter) and 7q36 deletion, 46,XX,der(7)t(3;7)(p23;q36), resulting from a paternal t(3;7) reciprocal translocation. The pregnancy was terminated. autopsy further confirmed the presence of arrhinencephaly, agenesis of the corpus callosum and a single ventricle of the brain. The phenotype of this antenatally diagnosed case is compared with those observed in 10 previously reported cases with simultaneous occurrence of partial trisomy 3p and terminal deletion 7q. All cases are associated with severe forms of holoprosencephaly and facial dysmorphism. This delineates an autosomal imbalance syndrome or a dosage effect involving duplication of distal 3p/deficiency of terminal 7q and dysmorphogenesis of the forebrain and mid-face.- - - - - - - - - - ranking = 2keywords = brain (Clic here for more details about this article) |
5/67. Coexistent holoprosencephaly and Chiari II malformation.Chiari II malformations and holoprosencephaly have been considered to be brain malformations that differ with respect to teratogenic insult, embryologic mechanism, and morphology. We herein describe coexistent Chiari II malformation and holoprosencephaly that occurred in a viable infant. A review of the literature regarding Chiari II malformations and holoprosencephaly suggests that a disturbance to the mesenchyme in early embryologic life may be the cause of both malformations.- - - - - - - - - - ranking = 1keywords = brain (Clic here for more details about this article) |
6/67. Inverted duplication of the distal short arm of chromosome 3 associated with lobar holoprosencephaly and lumbosacral meningomyelocele.A fetus with lobar holoprosencephaly and lumbosacral meningomyelocele associated with duplication of the short arm of chromosome 3 is reported. The anomalies were detected on fetal ultrasound at 20 weeks' gestation and the autopsy findings correlated well with the prenatal findings. The fetal karyotype was 46,XY,der(3)del(3)(p26) dup(3)(p26p21.3). The association of holoprosencephaly with duplication 3p is well known, but to the best of our knowledge this is the first reported association of meningomyelocele with 3p duplication. These findings suggest that a gene or genes with a crucial role in central nervous system development are located on the short arm of chromosome 3.- - - - - - - - - - ranking = 0.96678708290715keywords = central nervous system, nervous system (Clic here for more details about this article) |
7/67. holoprosencephaly, sacral anomalies, and situs ambiguus in an infant with partial monosomy 7q/trisomy 2p and SHH and HLXB9 haploinsufficiency..We report an infant with holoprosencephaly (HPE), sacral anomalies, and situs ambiguus with a 46,XY,der(7)t(2;7)(p23.2;q36.1) karyotype as a result of an adjacent-1 segregation of a t(2;7)pat. The chromosomal abnormality was diagnosed prenatally after sonographic detection of HPE in the fetus. The baby was born at 37 weeks gestation, and died in the newborn period; he had dysmorphic features consistent with HPE sequence. Postmortem internal evaluation showed semilobar HPE, abdominal situs ambiguus, multiple segments of bowel atresia, dilatation of the ureters, and bony sacral anomalies. Molecular analysis confirmed hemizygosity for the SHH and HLXB9 genes, which are likely to be responsible for the HPE and sacral phenotypes, respectively. Immunohistochemical studies showed intact dopaminergic pathways in the mesencephalon, suggesting that midbrain dopamine neuron induction appears to require only one functioning SHH allele.- - - - - - - - - - ranking = 1keywords = brain (Clic here for more details about this article) |
8/67. Misclassification risk of patients with bilateral cleft lip and palate and manifestations of median facial dysplasia: A new variant of del(22q11.2) syndrome?The generic term median facial dysplasia (MFD) describes a subgroup of patients with cleft lip and palate exhibiting characteristic craniofacial defects: (1) short prolabium, (2) absence of frenulum labii, (3) hypoplasia of premaxilla, (4) absent upper central and lateral incisors of the cleft side, and (5) deficient septal cartilage and nasal spine. Gross brain malformations are usually absent in MFD. The same craniofacial malformations are also described in patients with holoprosencephaly sequence (HPE-S). We report on two male patients with bilateral cleft lip and palate showing the facial findings of MFD or HPE-S. Additional congenital malformations were anal atresia in one patient and severe cardiac defect in the other. In both, HPE was excluded by brain imaging, although uncommon brain anomalies were detected consisting of multiple white-matter lesions in the one patient and unusual enlargement and tortuosity of intracerebral blood vessels in both patients. In addition to facial anomalies, the patients also had psychiatric problems typically seen in velo-cardio-facial syndrome (VCFS). fluorescence in situ hybridization (FISH) analysis confirmed a 22q11.2 microdeletion in both.- - - - - - - - - - ranking = 3keywords = brain (Clic here for more details about this article) |
9/67. holoprosencephaly associated with an apparent isolated 2q37.1-->2q37.3 deletion.A female infant survived 5(1/2) hours after delivery at 33 weeks gestation. autopsy showed a lobar variant of holoprosencephaly (HPE). cytogenetic analysis revealed a 2q37.1-->2q37.3 deletion. This case represents the fourth reported case of HPE associated with partial monosomy 2q37 and the first with an apparent isolated 2q37 deletion. Chromosome segment 2q37.1-->2q37.3 may harbor yet another locus important in forebrain development, which, when disrupted, can lead to brain malformations within the HPE spectrum.- - - - - - - - - - ranking = 2keywords = brain (Clic here for more details about this article) |
10/67. Extramedullary hematopoiesis within a frontoethmoidal encephalocele in a newborn with holoprosencephaly.We present the first report of extramedullary hematopoiesis (EMH) in an encephalocele. The patient was a new-born with semilobar holoprosencephaly, a frontoethmoidal encephalocele, and a large subdural hematoma. The encephalocele appeared as a hemorrhagic mass, protruding from the forehead to cover the right eye, without involvement of the sinuses or nasopharynx. Computerized tomography and magnetic resonance imaging studies ruled out other forms of holoprosencephaly and confirmed the continuity of the brain with the extruded mass. immunohistochemistry confirmed the presence of an atrophic epithelium covering the mass. Histologic examination of the encephalocele revealed EMH both within and adjacent to malformed cerebral cortex, with a tendency for the hematopoietic cells to line up in columns within malformed cerebral cortex. We propose that a single event during the fourth week of gestation could both interrupt closure of the neural tube, giving rise to the encephalocele, and impair migration of the neural crest, leading to holoprosencephaly secondary to failure of neural crest derivatives to induce basomedial telencephalic differentiation. EMH may have been induced from hematopoietic stem cells in the richly vascular meningeal component of the encephalocele, in response to anemia and hypoxia.- - - - - - - - - - ranking = 1keywords = brain (Clic here for more details about this article) |
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