1/200. 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. ( info) |
2/200. 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. ( info) |
3/200. Syntelencephaly associated with connected transhemispheric cleft of focal cortical dysplasia. The authors report a female with syntelencephaly associated with a connected transhemispheric cleft of focal cortical dysplasia. Syntelencephaly is a rare anomaly characterized by fusion of the hemispheres in the posterior frontal and parietal regions and is considered a new variant of holoprosencephaly. Cranial magnetic resonance imaging of the patient revealed syntelencephaly associated with bilateral fused clefts of focal cortical dysplasia without the pial-ependymal seam, which was regarded as an incomplete type of schizencephaly. The underlying mechanism is discussed. ( info) |
| We present three cases of fetal holoprosencephaly diagnosed by transabdominal and transvaginal ultrasound examinations at 10 and 13 weeks' gestation. The diagnosis was based on two sonographic criteria: first, the intracranial finding of a single ventricle with a cerebral mantle and no visible midline structures but fusion of the thalami and corpus striatum; and, second, facial abnormalities, including hypotelorism. The ultrasound findings were confirmed by embryoscopy before abortion in one case and by pathological examination after abortion in two cases. Chromosome study of the three fetuses showed trisomy 18, triploidy and mosaic 18p deletion and duplication. ( info) |
| Alobar holoprosencephaly is an intracranial abnormality characterized by failure of proper cleavage of the prosencephalon, accompanied by incomplete midfacial development. The prenatal sonographic diagnosis of alobar holoprosencephaly was first described in 1984; however, there have been only two reports of alobar holoprosencephaly diagnosed in the first trimester. We report a case of alobar holoprosencephaly diagnosed at 10 weeks of gestation. ( info) |
6/200. 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. ( info) |
7/200. First trimester sonographic diagnosis of holoprosencephaly. OBJECTIVE: To describe our experience with sonographic diagnosis of fetal holoprosencephaly in first trimester. SUBJECTS: A total of three fetuses with early prenatal diagnosis of holoprosencephaly were sonographically evaluated and followed up. RESULTS: The study revealed that all showed monoventricular cavity, fused thalami, no falx and cavum septum pellucidum. All of them were correctly diagnosed sonographically in the first trimester. Extracranial anomalies had also been identified in all three fetuses and all of them had facial abnormalities. Cytogenetic studies were successfully carried out in only one case. No polyhydramnios was demonstrated in all cases. CONCLUSION: This small series indicates that holoprosencephaly can be diagnosed in the first trimester. The most valuable clue to the diagnosis is the demonstration of the single ventricle. ( info) |
| 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. ( info) |
9/200. Histological findings in a case of alobar holoprosencephaly diagnosed at 10 weeks of pregnancy. A case of alobar holoprosencephaly diagnosed at 10 3 weeks' gestation by transabdominal and transvaginal ultrasound examination followed by histological confirmation is presented. The diagnosis was based on two sonographic criteria: intracranial finding of a single ventricle with a mantle and no visible midline structures but fusion of the thalami and corpus striatum, and facial abnormalities, including hypotelorism and proboscis. The fetal karyotype was triploidy. The ultrasound findings were confirmed by pathological examination. The histological findings of proboscis, single lens and single ventricle with neural tissue remnants are presented. ( info) |
10/200. Familial association of camptodactyly, mental retardation, whistling face and Pierre Robin sequence. Two sibs are reported with severe developmental retardation combined with the clinical triad of camptodactyly, whistling face and Pierre Robin sequence as clinical signs of fetal hypokinesia. In spite of tracheotomy, the first child of the family died 10 hours after birth. A sister of this child was born 1 year later. During pregnancy prenatal diagnosis of hydrocephaly was made by ultrasonographic examination. MRI scan showed holoprosencephaly. At 15 months of age psychomotor development is severely impaired, birth and length are delayed. ( info) |