Microarray analysis detects novel Pax3 downstream target genes

Pax3 is a transcription factor that is required for the development of embryonic neural tube, neural crest, and somatic derivatives. Our previous study (Mayanil, C. S. K., George, D., Mania-Farnell, B., Bremer, C. L., McLone, D. G., and Bremer, E. G. (2000) J. Biol. Chem. 275, 23259-23266) reveals that overexpression of Pax3 in a human medulloblastoma cell line, DAOY, resulted in an up-regulation in alpha-2,8-polysialyltransferase (STX) gene expression and an increase in polysialic acid on neural cell adhesion molecule. This finding suggests that STX might be a previously undescribed downstream target of Pax3. Because Pax3 is important in diverse cellular functions during development, we are interested in the identification of additional downstream targets of Pax3. We utilized oligonucleotide arrays and RNA isolated from stable Pax3 transfectants to identify potential target genes. A total of 270 genes were altered in the Pax3 transfectants as compared with the vector control and parental cell line. An independent analysis by cDNA expression array and real-time quantitative polymerase chain reaction of several genes confirmed the changes observed by the oligonucleotide microarray data. Of the genes that displayed significant changes in expression, several contain paired and homeodomain binding motifs of Pax3 in their promoter regions. Using promoter-luciferase reporter transfection assays and electromobility shift assays, we showed at least one previously undescribed downstream target, STX, to be a biological downstream target of Pax3. Thus we report several previously undescribed candidate genes to be potential downstream targets of Pax3.

Spina bifida outcome: a 25-year prospective

BACKGROUND

Open spina bifida is the most complex congenital abnormality compatible with long-term survival. This report outlines the 20- to 25-year outcome for our original cohort of patients with a myelomeningocele treated in a nonselective, prospective manner.

METHODS

Of the initial 118 children, 71 patients were available for our most recent review. Nineteen patients have been lost to follow-up and 28 patients have died. Data were collected on: motor level, shunt status, education/employment, seizure history, mobility, bladder/bowel continence, tethered cord, scoliosis, latex allergy, posterior cervical decompression, tracheostomy and/or gastrostomy tube.

RESULTS

Mortality (24%) continues to climb into young adulthood. Eighty-six percent of the cohort have cerebrospinal fluid diversion, with 95% having undergone at least one shunt revision. Thirty-two percent have undergone a tethered cord release, with 97% having an improvement or stabilization in their preoperative symptoms. Forty-nine percent have scoliosis, with 43% eventually requiring a spinal fusion. Sixteen patients (23%) have had at least one seizure. Eighty-five percent are attending or have graduated from high school and/or college. More than 80% of young adults have social bladder continence. Approximately 1/3 of patients are allergic to latex, with 6 patients having experienced a life-threatening reaction.

CONCLUSION

At least 75% of children born with a myelomeningocele can be expected to reach their early adult years. Late deterioration is common. One of the greatest challenges in medicine today is establishing a network of care for these adults with spina bifida.

Overexpression of murine Pax3 increases NCAM polysialylation in a human medulloblastoma cell line

Polysialic acid (PSA) is a developmentally regulated carbohydrate found primarily on neural cell adhesion molecules (NCAM) in embryonic tissues. The majority of NCAM in adult tissues lacks this unique carbohydrate, but polysialylated NCAM (PSA-NCAM) is present in adult brain regions where neural regeneration persists and in some pediatric brain tumors such as medulloblastoma, which show greater propensity for leptomeningeal spread. Pax3, a developmentally regulated paired homeodomain transcription factor, is thought to be involved in the regulation of neural cell adhesion molecules. Overexpression of murine Pax3 into a human medulloblastoma cell line (DAOY) resulted in an increase in NCAM polysialylation and a 2-4-fold increase in alpha2, 8-polysialyltransferase type II mRNA levels. No difference was observed in alpha2,8-polysialyltransferase type IV message. The addition of PSA to NCAM changed the adhesive behavior of these Pax3 transfectants. Transfectants expressing high PSA-NCAM show much less NCAM-dependent aggregation than those with less PSA-NCAM. In addition, Pax3 transfectants having high PSA-NCAM show heterophilic adhesion involving polysialic acid to heparan sulfate proteoglycan and agrin. These observations suggest that a developmentally regulated transcription factor, Pax3, could affect NCAM polysialylation and subsequently cell-cell and cell-substratum interaction.

Myelocystocele-cloacal exstrophy in a pedigree with a mitochondrial 12S rRNA mutation, aminoglycoside-induced deafness, pigmentary disturbances, and spinal anomalies

A large Filipino-American family with progressive matrilineal hearing loss, premature graying, depigmented patches, and digital anomalies was ascertained through a survey of a spina bifida clinic for neural crest disorders. Deafness followed a matrilineal pattern of inheritance and was associated with the A1555G mutation in the 12S rRNA gene (MTRNR1) in affected individuals as well as unaffected maternal relatives. Several other malformations were found in carriers of the mutation. The proband had a myelocystocele, Arnold-Chiari type I malformation, cloacal exstrophy, and severe early-onset hearing loss. Several family members had premature graying, white forelock, congenital leukoderma with or without telecanthus, somewhat suggestive of a Waardenburg syndrome variant. In addition to the patient with myelocystocele, two individuals had scoliosis and one had segmentation defects of spinal vertebrae. The syndromic characteristics reported here are novel for the mitochondrial A1555G substitution, and may result from dysfunction of mitochondrial genes during early development. However, the mitochondrial A1555G mutation is only rarely associated with neural tube defects as it was not found in a screen of 218 additional individuals with spina bifida, four of whom had congenital hearing loss.

Neural crest anomaly syndromes in children with spina bifida

A hereditary contribution to the etiology of neural tube defects (NTDs) has been suggested by clinical studies and animal models. To evaluate the hypothesis that common genes are important for both neural tube defects and neural crest anomalies, we examined children with developmental abnormalities of the spinal cord for anomalies of neural crest-derived structures. Neural crest anomalies, particularly auditory and pigmentary disorders, were identified and classified according to inheritance and type of anomaly. Of the 515 children screened, 44 (8.5%) had neural crest anomalies, 20 (3.9%) of which were apparently familial. Another 19 (3.7%) families had neural crest anomalies in two or more close relations, but the NTD subject was unaffected. Sixteen (3.1%) children with NTDs had a recognizable syndrome, including nine (1.7%) with a subtype of the Waardenburg syndromes. The coincidence of familial neural crest anomaly syndromes in subjects with spina bifida implies that defects in genes underlying neural crest development may contribute to the etiology of neural tube defects in a fraction of cases. The rate of anomalies and familial syndromes of neural crest-derived structures must be assessed in an adequate control sample to evaluate whether or not these abnormalities constitute risk factors for NTDs.

The presence of transcription factors in chicken albumin, yolk and blastoderm

Embryonic development is determined by preset intrinsic programs and extrinsic signals. To explore the possibility that transcription factors are present at the onset of development, preparations of yolk, albumin, and blastoderm from unfertilized and fertilized white Leghorn chicken eggs were screened by a panel of 16 transcription factor antibodies with Western blot techniques. Yolk was positive for 13 transcription factors, whereas blastoderm was positive for 10, and albumin was positive for 5. In yolk, several transcription factors, GATA-2, E2F-1, MyoD, and TFIID, were developmentally regulated. These results indicate that intracellular yolk and extracellular albumin contain transcription factors which presumably influence early chick embryonic development from prefertilization to the late blastoderm stage. Thus, the utility of preset maternal transcription factors within yolk and albumin complement maternally derived mRNA to determine the early development of the zygote.

The biological resolution of malformations of the central nervous system

It has been known for years that the assembly of the nervous system is under genetic control. During the last 10 years, the genes that direct the formation of the brain and spinal cord have begun to be discovered at an amazing pace. Mutations in the fruit fly and advances in molecular genetics have led the way. Gene mutations that cause many of the malformations of the human brain and spinal cord are now known. This has many physician-scientists hoping that an understanding of cause might lead to cure.

Abdominal cerebrospinal fluid pseudocyst: A complication of ventriculoperitoneal shunt in children

The present paper is a retrospective analysis of 27 consecutive patients, treated for abdominal cerebrospinal fluid (CSF) pseudocyst at the Children's Memorial Hospital in the years 1991-1996. This series is compared to the previous experience from our institution. Treatment consisted of the removal of the ventriculoperitoneal (VP) shunt and placement of an external ventricular drain. Antibiotics were administered intravenously for 10 days. The cysts were aspirated intraoperatively in 9 patients and postoperatively with ultrasound guidance in 3 patients, while they resolved spontaneously in 15 others. In 21 of 27 cases (78%), the shunt could be reinserted into the abdomen in a new location. Four patients had a ventriculopleural shunt, and in 2 patients, a ventriculoatrial shunt was inserted. Forty-four percent of the patients had a positive culture on presentation. The positive culture rate was 77% for those 4 years old and younger and only 28% for those aged 5 and above (p = 0.03). We conclude that abdominal CSF pseudocysts are resolved by externalizing the shunt. A VP shunt can be safely reinserted in the majority of the patients. Infection, while an important factor, is not likely to account for all cases of pseudocyst.

Myelomeningocele and Waardenburg syndrome (type 3) in patients with interstitial deletions of 2q35 and the PAX3 gene: possible digenic inheritance of a neural tube defect

From a spina bifida clinic we have identified two patients with a syndrome of myelomeningocele and Waardenburg syndrome type 3 (WS3). The patients each possess a single, de novo, interstitial deletion of chromosome 2 (2q35-36.2), including the PAX3 gene. Deletion of PAX3 was confirmed by fluorescence in situ hybridization (FISH). Analysis with PAX3 and flanking microsatellites shows that the deleted interval of chromosome 2 is of paternal origin and is at least 2 and 6 cM in the two patients. Interstitial deletions in this region result in the Waardenburg syndrome (WS1), but have not been associated with neural tube defects (NTDs). Although other etiologies have not been formally excluded, these patients raise the possibility of a digenic etiology of their NTDs via a genetic interaction of the deleted PAX3 gene with a second unidentified locus.

Care of the neonate with a myelomeningocele

Important decisions are made at the first meeting of the pediatric neurosurgeon and the parents of a child born with a myelomeningocele. It is essential that the neurosurgeon be aware of the most recent outcome data for children born with a myelomeningocele. Only when armed with this information can he or she make it possible for the family to participate in an informed decision. An understanding of the ethical principles involved in deciding for an individual too young to make any decision is a major part of this process.

Ultrastructural studies of primary congenital glaucoma in rabbits

BACKGROUND

The cause of congenital glaucoma is unknown.

METHODS

To determine whether the site of impaired aqueous outflow is the entrance to the trabecular meshwork (TM), within the TM, the aqueous drainage plexus, or a combination thereof, the process of TM development was examined by scanning and transmission electron microscopy on postnatal day 3 and weeks 1, 2, 3, 4, and 6 in New Zealand rabbits homozygous for the buphthalmic (bu/bu) gene compared with age-matched controls.

RESULTS

Openings to the entrance of the TM in congenital glaucoma were observed, and there was no evidence of an endothelial membrane occluding aqueous flow to the TM. The morphology of the congenital glaucoma TM was abnormal in all bu/bu rabbits by 2 weeks and was characterized by a smaller entrance to the TM at the iris base, smaller intertrabecular openings within and between the trabecular lamellae, and at 6 weeks, iris pillars with extensive lateral extensions in the angle recess. Most intertrabecular spaces were open, however, the inner intertrabecular spaces adjacent to the aqueous plexus were compressed.

CONCLUSION

These results suggest the development of congenital glaucoma, which involves a mutation in an autosomal recessive gene and leads to loss of function of a gene(s) required for the differentiation of the TM.

Functional opening of the fourth ventricular outlet in C57BL/6J and delayed splotch mouse embryos

To compare the functional development of the fourth ventricular outlet in the myeloschisis-Chiari malformation complex with that of a normal brain, the chronological development of the outlet in C57BL/6J non-neural-tube defect mouse embryos was examined as the first step. Then we compared the results with those of homozygotic delayed splotch (Spd) mouse embryos which had neural-tube defects (NTDs). Ferrous chloride (Prussian blue) solution was injected into the lateral or mesencephalic ventricle on gestation days 13-16 in the case of control C57BL/6J mouse embryos and on gestation days 14-16 in the case of homozygotic Spd mouse embryos which had open spinal NTDs and hindbrain anomalies comparable to human Chiari malformation. At 30 min after the injection, acid fixative was infused through the heart to set off the Prussian blue reaction, which makes the dye visible by the precipitation of ferric chloride. According to the present method, more than 75% of C57BL/6J mouse (non-NTD control) embryos showed the evidence of function of the fourth ventricular (4V) outlet from gestation day 15. It was difficult to apply the same method to Spd mouse embryos with NTDs due to the small size of ventricles. Only 4 injections were successful, of which 3 showed the functioning evidence of the 4V outlet. Though the number of mouse embryos with NTDs studied was small, the results suggest that the chronological progress of functional opening of the fourth ventricle in mouse embryos with NTDs is similar to that of control non-NTD embryos.

The tethered spinal cord: diagnosis, significance, and management

Tethered cord is the result of fixation of the spinal cord, which limits motion in the caudal-rostral direction. Most children either have cutaneous markers or a predisposing condition. Prophylactic release of the spinal cord can prevent the long-term disabilities associated with this condition. Although delayed release, following the onset of a neurological deficit, may reverse some lost function, it is unlikely to restore bladder and bowel function.

Developmental normo-maturation of brainstem auditory evoked potentials in children with asymptomatic meningo-myelocele during the first year of life

It is difficult to predict the onset of clinical symptoms due to Chiari II malformation. Brainstem auditory evoked potentials (BAEPs) may be useful to select potential candidates for surgery. We studied 158 BAEPs in 134 asymptomatic children with meningomyelocele (MMC) during the first year of life. Both wave latencies (WLs) and interpeak latencies (IPLs) in asymptomatic children with MMC gradually became shorter during the first year of life. In particular, the shortening of III-V IPLs was observed in the asymptomatic children with MMC from 2 or 3 weeks to 4-6 months of age. This may be a characteristic parameter of the development of the intrinsic brainstem function in patients with MMC. Comparison of these data on BAEPs in asymptomatic children with MMC with the published data on BAEPs in normal neonates and infants showed that the maturation of brainstem function was delayed in the asymptomatic children with MMC during the first year of life. These data on asymptomatic neonates and infants with MMC could potentially be a good reference for selecting the modalities of treatment in patients with MMC associated with symptomatic Chiari II malformation.

Presentation and management of hydromyelia in children with Chiari type-II malformation

Hydromyelia in patients with myelomeningocele and Chiari-II malformation is a relatively frequent finding on MRI studies. However, not all children develop symptoms from the hydromyelia that requires treatment. Furthermore, treatment of hydromyelia in spina bifida patients is rather complex due to the associated malformations. The authors retrospectively analyzed 231 MRI studies carried out on spina bifida patients who presented neurological deterioration. Hydromyelia was found in 48.5% of the patients. Forty-five children with severe hydromyelia required treatment. These patients were first divided into 2 groups: those with holocord hydromyelia, and those with a segmental lesion. Fifteen patients presented symptoms characteristic of symptomatic Chiari-II malformation: neck rigidity; swallowing difficulty; pain in the upper extremeties; weakness or spasticity in the upper extremeties. Eighteen patients presented symptoms typical of the tethered cord syndrome: scoliosis; worsening bladder and/or bowel function; pain in the lower extremeties; weakness or spasticity in the lower extremeties. Twelve patients presented a mixed-type symptomatology. These patients subsequently underwent posterior cervical decompression, tethered cord release or insertion of a hydromyelia-pleural shunt according to the type of presenting symptoms and to the extent of the hydromyelic lesion. A pattern of successful treatment was identified for each type of presenting clinical and radiological picture. This has allowed the authors to determine an algorithm for optimal treatment of hydromyelia associated with Chiari-II malformation and myelomeningocele, which is proposed here.

Spinal lipomas in children: outcome of 270 procedures

Spinal lipomas are a common cause of spinal cord tethering. Recently, prophylactic surgical removal of spinal lipomas has been questioned, especially of the conus medullaris. Unfortunately, few statistically significant series have been reported. A total of 213 children with spinal lipomas were operated on at the Children's Memorial Hospital in Chicago, Ill., USA, on whom 270 procedures were carried out between 1975 and 1995. The status of these children was retrospectively reviewed to determine the differences in outcome between patients prophylactically operated on before the onset of symptoms and those operated on after the onset of symptoms. Fifty-five patients presented with a lipoma of the filum terminale and 158 with a lipoma of the conus medullaris. In the filum terminale group, 28 were asymptomatic at the initial operation, and 27 presented with symptoms. Of the asymptomatic children with filum terminale lipomas, none worsened after surgery, and all remained asymptomatic throughout follow-up (mean follow-up: 3.4 years). Benefits were also observed for the symptomatic patients in this group as no cases of further deterioration were noted, and 5 patients returned to normal clinical status. In the conus group, 71 patients were asymptomatic at initial surgery, and 87 presented with symptoms. In the case of conus medullaris lipomas, 9 of the 71 children who were operated on prophylactically, later deteriorated (mean follow-up: 6.2 years) and required a second untethering operation which resolved all symptoms in 4 cases. Thus, 5 of 71 deteriorated, while 66 remained normal (93%) throughout the period of follow-up. On the other hand, of the 87 patients operated on after the onset of symptoms, 36 (41%) deteriorated further and required subsequent reoperations. In these 87 children, the final outcome at the end of follow-up (mean follow-up: 6.6 years) showed that 20 (23%) patients had deteriorated compared to initial presentation and 44 (51%) remained at initial clinical baseline, while 23 (26%) improved or returned to normal clinical status. Prophylactic surgery in the case of the asymptomatic infant with a spinal lipoma showed a clear benefit. Good outcome was also observed when surgery was carried out after the onset of symptoms. Prophylactic surgery also had a better general outcome by actuarial calculations when only patients with a follow-up of more than 5 years were considered. Deterioration occurred in 5 (16.7%) of the 30 children with a follow-up of more than 5 years, while 25 (83.3%) remained normal. Furthermore, in cases which had prophylactic surgery, there was not only a smaller incidence of deterioration requiring a reoperation, but this group of patients also experienced a longer time interval between initial surgery and the need for reoperation compared to the patients operated on after the onset of symptoms. The authors conclude that spinal lipomas should be operated on as soon as possible on a prophylactic basis, and careful and constant follow-up should be carried out to permit prompt reintervention in cases with deterioration.

Pathological changes in exposed neural tissue of fetal delayed splotch (Spd) mice

If meningomyelocele is indeed a progressive intrauterine process, then early delivery or possibly intrauterine repair of meningomyelocele becomes an issue. Utilizing the delayed splotch (Spd) mouse, a genetically transmitted neural tube defect model, we looked for evidence of abnormalities of neural tissue exposed to amniotic fluid. Affected embryonic and fetal mice were examined with the light microscope, and also with the transmission and scanning electron microscope. Neuronal development and programmed cell death paralleled normal fetal development. No evidence of inflammation on or within the exposed neural tissue was observed. Because the vascular supply to the alar and basilar plate are different, vascular development was also examined and no difference could be found. In conclusion, we found no evidence of deterioration of the exposed neural tube during the gestational period of a mouse, which suggests that exposure of unneurulated spinal cord to amniotic fluid is not a risk factor to the fetus with a neural tube defect.

Tethered cord syndrome in low motor level children with myelomeningocele

The clinical presentation of tethered spinal cord and the results of tethered cord release were examined in a group of 30 low motor level (L3 and below) children with a history of myelomeningocele without concomitant CNS complications. Changes in orthopedic and/or neurologic status formed the basis of consideration for tethered cord release. Clinically, these patients presented with a new onset or recently progressing scoliosis, spasticity with or without contractures, decrease in motor function and low back pain at the site of closure. One or more of these findings was present in all cases and led to the suspicion of tethered spinal cord. The diagnosis of tethered cord was confirmed in all cases by MRI or CT myeolography. In order to isolate tethering as the etiology for the patients' clinical deterioration, patients with concomitant CNS complications, e.g. shunt dysfunction or hydromyelia were excluded from the study. Twenty-nine such patients, of an initial 59, who would have otherwise been considered, were excluded on the basis of this criteria of concomitant CNS complications. The results of release 1 year after the procedure were as follows: regarding scoliosis, in 75% of cases the curve either remained stable or decreased by more than 10 degrees, with 25% experiencing curve progression of > 10 degrees. The most recent follow-up in this group revealed that 11.8% experienced a decrease in curvature of >10 degrees; 47.1% remained stable, and 41.2% ultimately progressed 10 degrees. In the group with spasticity, 43.8% improved; 56.3% remained stable, and none worsened. Most (78.6%) of the children who had experienced a decline in motor function improved postoperatively, and all those with back pain experienced complete resolution. In conclusion, tethered cord release in symptomatic low lumbar and sacral level children with myelomeningocele appears to be of benefit, especially with respect to stabilization of scoliosis in selected patients, back pain at the site of closure, and prior decline in motor function. Results in the cases with spasticity were more equivocal.

MR imaging of the pediatric spine

An overview of MR imaging of the pediatric spine is presented with a systematic approach to the analysis of spinal dysraphic disorders. An introduction to the most commonly used MR imaging techniques, with an emphasis on the newer pulse sequence of cine MR flow of the cerebrospinal fluid and embryogenesis of the spine and spinal cord, provides the orientation for diagnosis of this common pediatric disorder.

Natural course of brainstem auditory evoked potentials in infants less than 6 months old with asymptomatic meningomyelocele

It is difficult to estimate the accurate onset of symptoms clinically resulting from Chiari II malformation. Brainstem auditory evoked potentials (BAEPs) may be a useful method in the selection of potential candidates for surgery. We studied 153 BAEPs in 131 asymptomatic infants under 6 months of age with meningomyelocele (MMC). Both the wave latencies and interpeak latencies (IPLs) gradually became shorter during the first 6 months of life in asymptomatic infants with MMC. In particular, shortening of the III-V IPLs and the I-V IPLs was observed from 1 to 4-6 months of age in these infants. These may be characteristic parameters of central auditory function (III-V IPLs) and global auditory function (I-V IPLs). Maturation of brainstem function as viewed by BAEPs in asymptomatic infants with MMC was delayed when compared to data in normal neonates and infants. These data on asymptomatic infants with MMC could potentially be a good reference for selecting the modalities of treatment in infants with symptomatic Chiari II malformation.

Postneurulation rapid brain growth represents a critical time for encephalocele formation: a chick model

Current theory regarding the pathogenesis of encephaloceles suggests that the defect occurs after neurulation is completed in which brain tissue herniates through defective mesodermal elements necessary for skull modeling. To better delineate the mechanisms of encephalocele development, we performed a variety of microsurgical manipulations in the developing cranium of the chick embryo during the postneurulation period of early rapid brain growth. The results of the study revealed that encephaloceles could be induced in 78% of chick embryos manipulated at stage 26 that had evidence of marked decompression of the primitive ventricle. On the other hand, control embryos or embryos manipulated without ventricular decompression at stage 26 did not develop encephaloceles (0 of 32). Embryos with decompression of the primitive ventricle treated at earlier stages (20-24) showed only a 5% incidence of encephaloceles. These findings suggest that there is both a critical time point during postneurulation rapid brain growth when encephaloceles are prone to occur and a mesenchymal defect associated with decompression of the primitive ventricle that must be present to induce encephaloceles.

Imaging of terminal myelocystoceles

This article presents a retrospective analysis of the presentation, imaging studies, and associated findings in 20 children with surgically and histologically proven terminal myelocystoceles. All 20 children presented at birth with a black mass; 13 had cloacal extrophy. The patient population was comprised of 15 girls and 5 with ambiguous genitalia: Of the imaging studies, 8 had plain radiographs, 6 myelography-computed tomography, 11 ultrasound, and 14 magnetic resonance. The associated findings included Chiari I (eight patients), Chiari II (one patient), hydromyelia (three patients), hydrocephalus (three patients), and vertebral segmentation anomalies (six patients). Magnetic resonance imaging was the best imaging modality to diagnose and evaluate children with a myelocystocele. Magnetic resonance imaging demonstrated the classic findings: a terminal cyst of the central canal of the spinal cord that is tethered and herniated with arachnoid and cerebrospinal fluid through an area of spinal dysphria onto the back as a mass.

A new catheter for use in severe shunt infections and pyocephalus. A technical note

A catheter is described for use in severe shunt infection where the white blood cell count in the CSF exceeds 1,000 cells/mm3. The catheter allows for simultaneous irrigation and drainage of the ventricular system.

Operative resection of 100 spinal lipomas in infants less than 1 year of age

A retrospective analysis of 100 children followed at Children's Memorial Hospital, Chicago, who underwent surgery for a spinal lipoma was performed. The mean follow-up was 5 years. We found that an operation performed during the 1st year of life with the goal of untethering the spinal cord and debulking the spinal lipoma was safe and effective, whereas a cosmetic (nonuntethering) procedure always led to delayed postoperative deterioration (symptomatic tethered cord). Of the infants that presented with motor, urologic or orthopedic symptoms, 39% improved, 58% stabilized, while 3% worsened as a result of surgery. No asymptomatic infant deteriorated postoperatively and 93% of these children remained symptom-free at follow-up (mean follow-up was 44 months). The overall outcome of infants after untethering procedures in this study was significantly better than the natural history of spinal lipomas. Several risk factors were identified that may predispose children to delayed postoperative deterioration: an initial cosmetic procedure; the presence of preoperative symptoms, and the presence of a lipomyelomeningocele.

Mechanisms of mutant genes in spina bifida: a review of implications from animal models

Spina bifida (spinal neural tube defects) has been shown to be caused by an abnormality in closure of the neural tube. Basic scientific research has rapidly progressed in experimental embryology and molecular genetics to give new insights into the pathogenesis of defective neural tube closure. The chick and the mouse have proved to be the best animal models for study because of similarities to human neurulation. The embryonic mechanisms for spina bifida appear to be under the control of mutant early regulating genes and modifying genes. Faulty early gene function in chicks and mice has been reported to result in abnormalities of neuronal and nonneuronal tissues important for neural tube closure. Research efforts are being aimed at understanding the inductive interactions and downstream target sites for early regulating genes. Elucidation of the genetic roadmap for the control of neurulation will give further insights into the causes of spina bifida.

Hereditary factors in the etiology of neural tube defects. Results of a survey

Ongoing research in the etiology of neural tube defects is increasingly being directed towards the molecular mechanisms at work in the formation of these complex lesions. We undertook to review the family history of patients in a large myelomeningocele/spina bifida clinic in an effort to identify genetic trends in these families, particularly as they relate to current research efforts and laboratory models. Surveys were received from 363 patients (35.5% of the clinic population) and analyzed. The myelomeningocele recurrence rate was 4.3%. Seven sets of twins were identified and all were discordant for their spinal lesions. A family history of spina was found to be evenly distributed between maternal and paternal relatives, rather than tending to follow through the maternal side. Epilepsy was more commonly found on the maternal side of the family, most likely reflecting the postulated causal relationship between maternal anticonvulsant use and the occurrence of spina bifida, although also possibly supporting the concept that a genetic predisposition for maternal epilepsy may also be associated with a higher frequency of birth defects among children of epileptics, independent of anticonvulsant use. Patients with spina bifida in the setting of Waardenburg syndrome and fragile X syndrome were also identified and will be discussed.