Periventricular heterotopia: an X-linked dominant epilepsy locus causing aberrant cerebral cortical development

Periventricular Heterotopias: Neuroependymal Abnormalities

Periventricular nodular heterotopia (PVNH) is a group of malformation of cortical development characterized by ectopic neuronal nodules, located along the lateral ventricles. Magnetic resonance imaging can identify gray matter nodules located in wall of ventricles, which appear as island having the same signal of gray matter within white matter. The symptomatological spectrum is various, but the most common clinical presentation is with epileptic seizures, often a drug-resistant type. Features as severity, age of presentation, and associated malformations depend on the underlying etiology. From a genetic point of view, FLNA1 and ERMARD are acknowledged to be the main target of mutations that cause PVNH, although recently many other genes have shown a clear pathogenetic involvement. PVNH may manifest as a solitary discovery in brain imaging or present in conjunction with various other brain or systemic abnormalities. The diagnosis of PVNH is mainly carried out with electroneurophysiological and neuroimaging examinations, while the etiological diagnosis is made with genetic investigations. Treatment consists of use of anticonvulsant drugs, but no significant difference exists among them. In addition, frequently, PVNH-related seizures show poor response to drug, leading to requirement for surgical treatment, performed taking advantages from stereotactic ablative techniques that have a meaningful impact on surgical outcome.

Sustained generation of neurons destined for neocortex with oxidative metabolic upregulation upon filamin abrogation

Neurons in the neocortex are generated during embryonic development. While the adult ventricular-subventricular zone (V-SVZ) contains cells with neural stem/progenitors' characteristics, it remains unclear whether it has the capacity of producing neocortical neurons. Here, we show that generating neurons with transcriptomic resemblance to upper layer neocortical neurons continues in the V-SVZ of mouse models of a human condition known as periventricular heterotopia by abrogating Flna and Flnb. We found such surplus neurogenesis was associated with V-SVZ's upregulation of oxidative phosphorylation, mitochondrial biogenesis, and vascular abundance. Additionally, spatial transcriptomics analyses showed V-SVZ's neurogenic activation was coupled with transcriptional enrichment of genes in diverse pathways for energy metabolism, angiogenesis, cell signaling, synaptic transmission, and turnovers of nucleic acids and proteins in upper cortical layers. These findings support the potential of generating neocortical neurons in adulthood through boosting brain-wide vascular circulation, aerobic adenosine triphosphate synthesis, metabolic turnover, and neuronal activity.

Grey matter heterotopia subtypes show specific morpho-electric signatures and network dynamics

Grey matter heterotopia (GMH) are neurodevelopmental disorders associated with abnormal cortical function and epilepsy. Subcortical band heterotopia (SBH) and periventricular nodular heterotopia (PVNH) are two well-recognized GMH subtypes in which neurons are misplaced, either forming nodules lining the ventricles in PVNH, or forming bands in the white matter in SBH. Although both PVNH and SBH are commonly associated with epilepsy, it is unclear whether these two GMH subtypes differ in terms of pathological consequences or, on the contrary, share common altered mechanisms. Here, we studied two robust preclinical models of SBH and PVNH, and performed a systematic comparative assessment of the physiological and morphological diversity of heterotopia neurons, as well as the dynamics of epileptiform activity and input connectivity. We uncovered a complex set of altered properties, including both common and distinct physiological and morphological features across heterotopia subtypes, and associated with specific dynamics of epileptiform activity. Taken together, these results suggest that pro-epileptic circuits in GMH are, at least in part, composed of neurons with distinct, subtype-specific, physiological and morphological properties depending on the heterotopia subtype. Our work supports the notion that GMH represent a complex set of disorders, associating both shared and diverging pathological consequences, and contributing to forming epileptogenic networks with specific properties. A deeper understanding of these properties may help to refine current GMH classification schemes by identifying morpho-electric signatures of GMH subtypes, to potentially inform new treatment strategies.

Between neurons and networks: investigating mesoscale brain connectivity in neurological and psychiatric disorders

The study of brain connectivity has been a cornerstone in understanding the complexities of neurological and psychiatric disorders. It has provided invaluable insights into the functional architecture of the brain and how it is perturbed in disorders. However, a persistent challenge has been achieving the proper spatial resolution, and developing computational algorithms to address biological questions at the multi-cellular level, a scale often referred to as the mesoscale. Historically, neuroimaging studies of brain connectivity have predominantly focused on the macroscale, providing insights into inter-regional brain connections but often falling short of resolving the intricacies of neural circuitry at the cellular or mesoscale level. This limitation has hindered our ability to fully comprehend the underlying mechanisms of neurological and psychiatric disorders and to develop targeted interventions. In light of this issue, our review manuscript seeks to bridge this critical gap by delving into the domain of mesoscale neuroimaging. We aim to provide a comprehensive overview of conditions affected by aberrant neural connections, image acquisition techniques, feature extraction, and data analysis methods that are specifically tailored to the mesoscale. We further delineate the potential of brain connectivity research to elucidate complex biological questions, with a particular focus on schizophrenia and epilepsy. This review encompasses topics such as dendritic spine quantification, single neuron morphology, and brain region connectivity. We aim to showcase the applicability and significance of mesoscale neuroimaging techniques in the field of neuroscience, highlighting their potential for gaining insights into the complexities of neurological and psychiatric disorders.

Network of autoscopic hallucinations elicited by intracerebral stimulations of periventricular nodular heterotopia: An SEEG study

Periventricular nodular heterotopias (PVNH) are areas of neurons abnormally located in the white matter that might be involved in physiological cortical functions. Autoscopic hallucinations are changes in self-consciousness determined by a mismatch in integration of multiple sensory inputs. Our goal is to highlight the brain network involved in generation of autoscopic hallucination elicited by electrical stimulation of a PVNH in a drug resistant epilepsy patient. Our patient was explored using stereo-electroencephalography with electrodes covering the right posterior temporal PVNH and the adjacent cortex. Direct electrical high frequency stimulation of the PVNH elicited autoscopic hallucinations mainly involving the face and upper trunk. We then used multiple modalities to determine brain connectivity: single pulse electrical stimulation of the PVNH and stimulation-evoked potentials were used to highlight resting state effective connectivity. High-frequency stimulation using alternating polarity pulses enabled us to identify the network involved, time-locked to the clinical effect and to map symptom-related effective connectivity. Functional connectivity using a non-linear regression method was used to determine dependencies between different cortical regions following the stimulation. Finally, structural connectivity was highlighted using deterministic fiber tracking. Multi-modal connectivity analysis identified a network involving the PVNH, occipital and temporal neocortex, fusiform gyrus and parietal cortex.

Hemizygous FLNA variant in West syndrome without periventricular nodular heterotopia

Pathogenic FLNA variants can be identified in patients with seizures accompanied by periventricular nodular heterotopia (PVNH). It is unusual to find FLNA aberrations in epileptic patients without PVNH on brain imaging. We report a boy with cryptogenic West syndrome followed by refractory seizures and psychomotor delay. We performed whole-exome sequencing and identified a de novo missense variant in FLNA. It is noteworthy that this patient showed no PVNH. As no other pathogenic variants were found in epilepsy-related genes, this FLNA variant likely caused West syndrome but with no PVNH.

Periventricular nodular heterotopia in a Chihuahua

Periventricular nodular heterotopia is a common neuronal malformation in humans, often leading to epilepsy and other neurologic diseases. A 2‐month‐old female Chihuahua weighing 750 g was examined because of a history of epileptic seizures and abnormalities in gait and behavior. Results of the clinical examination were consistent with a multifocal neurologic disease with localization in the forebrain and spinovestibular system. The magnetic resonance imaging showed multiple bilateral periventricular nodules isointense to gray matter and ventriculomegaly. Histopathological and immunohistological examination of the brain revealed that periventricular nodules consisted of neurons, fewer astrocytes, and some oligodendroglia consistent with periventricular nodular heterotopias.

Reading deficits correlate with cortical and subcortical volume changes in a genetic migration disorder

Periventricular nodular heterotopia (PNH) is the most common type of epileptogenic neuronal migration disorder, and often presents with epilepsy and reading disability. The functional role of ectopic nodules has been widely studied. However, the associated structural cortical and subcortical volumetric alterations have not been well characterized. Moreover, it is unknown whether a correlation between volumetric changes and behavioral problems exists.40 subjects with bilateral PNH and 40 matched healthy controls were enrolled in this study. The total cerebral, gray matter, white matter, and cerebrospinal fluid (CSF) volumes were compared between the two groups. Furthermore, structural and functional correlations were evaluated between volumetric changes and reading disability.There were no significant differences detected in total cerebral, gray matter or CSF volumes between the two groups, but there was a significant trend of larger gray-matter volume in PNH. Specifically, smaller white matter volumes were found in the PNH patients. Moreover, the volume of white matter was negatively related to time in the digit rapid naming task and a similar but insignificant trend was seen between the volume of gray matter and backward digit span.These findings suggest that reading disability exists in our sample of bilateral PNH. Periventricular nodules would have normally migrated to the overlying cortex. However, the total cerebral, gray matter, and CSF volumes were unaffected. Alterations in neuronal migration may have an impact in the white matter associated reading dysfluency, that is, visually normal.

Rainer W. Guillery and the genetic analysis of brain development

Ray Guillery had broad research interests that spanned cellular neuroanatomy, but was perhaps best known for his investigation of the connectivity and function of the thalamus, especially the visual pathways. His work on the genetics of abnormal vision in albino mammals served as an early paradigm for genetic approaches for studying brain connectivity of complex species in general, and remains of major relevance today. This work, especially on the Siamese cat, illustrates the complex relationship between genotype and physiology of cerebral cortical circuits, and anticipated many of the issues underlying the imperfect relationship between genes, circuits, and behavior in mammalian species including human. This review also briefly summarizes studies from our own lab inspired by Ray Guillery's legacy that continues to explore the relationship between genes, structure, and behavior in human cerebral cortex.

Thoracic aortic aneurysm in patients with loss of function Filamin A mutations: Clinical characterization, genetics, and recommendations

The frequency and gender distribution of thoracic aortic aneurysm as a cardiovascular manifestation of loss-of-function (LOF) X-linked FilaminA (FLNA) mutations are not known. Furthermore, there is very limited cardiovascular morbidity or mortality data in children and adults. We analyzed cardiac data on the largest series of 114 patients with LOF FLNA mutations, both children and adults, with periventricular nodular heterotopia (PVNH), including 48 study patients and 66 literature patients, median age of 22.0 years (88 F, 26 M, range: 0-71 years), with 75 FLNA mutations observed in 80 families. Most (64.9%) subjects had a cardiac anomaly or vascular abnormality (80.8% of males and 60.2% of females). Thoracic aortic aneurysms or dilatation (TAA) were found in 18.4% (n = 21), and were associated with other structural cardiac malformations in 57.1% of patients, most commonly patent ductus arteriosus (PDA) and valvular abnormalities. TAA most frequently involved the aortic root and ascending aorta, and sinus of Valsalva aneurysms were present in one third of TAA patients. Six TAA patients (28.5%) required surgery (median age 37 yrs, range 13-41 yrs). TAA with its associated complications was also the only recorded cause of premature, non-accidental mortality in adults (2 M, 2 F). Two adult patients (1 F, 1 M, median 38.5 yrs), died of spontaneous aortic rupture at aortic dimensions smaller than current recommendations for surgery for other aortopathies. Data from this largest series of LOF FLNA mutation patients underscore the importance of serial follow-up to identify and manage these potentially devastating cardiovascular complications.

Prenatally diagnosed periventricular nodular heterotopia: Further delineation of the imaging phenotype and outcome

OBJECTIVES

Periventricular nodular heterotopia (PNH) is a malformation of cortical development which presents with heterogeneous imaging, neurological phenotype and outcome. There is a paucity of comprehensive description detailing the prenatal diagnosis of PNH. The aim of this study is to report neuroimaging features and correlated outcomes in order to delineate the spectrum of prenatally diagnosed PNH.

METHODS

It was a retrospective study over 15 years in five tertiary centers. All fetuses with prenatally diagnosed PNH were collected. Fetal ultrasound and MRI were reviewed and genetic screening collected. Prenatal findings were analyzed in correlation to fetopathological analyses and post-natal follow up.

RESULTS

Thirty fetuses (22 females and 8 males) with PNH were identified. The two major ultrasound signs were ventriculomegaly associated with dysmorphic frontal horns (60%) and posterior fossa anomalies (73.3%). On MRI, two groups of PNH were identified: the contiguous and diffuse PNH (n = 15, 50%), often associated with megacisterna magna, and the non-diffuse, either anterior, posterior or unilateral PNH. FLNA mutations were found in 6/11 cases with diffuse PNH. Additional cortical malformations were exclusively observed in non diffuse PNH (9/15; 60%). Twenty-four pregnancies (80%) were terminated. Six children aged 6 months to 5 years are alive. Five have normal neurodevelopment (all had diffuse PNH) whereas one case with non diffuse PNH has developmental delay and epilepsy.

CONCLUSION

PNH is heterogeneous but patients with diffuse PNH are a common subgroup with specific findings on prenatal imaging and implications for prenatal counseling.

Periventricular nodular heterotopia in 22q11.2 deletion and frontal lobe migration

Objective

We aimed to delineate the distribution of periventricular nodular heterotopia (PNH) in patients with 22q11.2 microdeletion syndrome (22q11.2DS) and place this in the context of other genetic forms of PNH.

Methods

We retrospectively analyzed brain imaging and postmortem data available for adult patients with 22q11.2DS. We included only those with good quality MRI data (n = 29) in addition to two patients with PNH identified through postmortem studies. We also reviewed the pattern of PNH in all genetic conditions reported with this phenotype.

Results

Of the total seven patients (M = 4, F = 3; age: 19–61 years) identified to have PNH, six had a history of seizures, six had schizophrenia, six had variable levels of intellectual disability, and two had obsessive compulsive disorder. In all seven patients, the nodules were located over the dorsal pole of the frontal horn of the lateral ventricles. The nodules were small, noncontiguous, and ranged in number from 1 to 10 per individual. Our review identified 37 genetic conditions associated with PNH. With the cases reported here, 22q11.2DS becomes the fifth most commonly reported genetic condition, and the third most common copy number variation, associated with PNH.

Interpretation

The neuropsychiatric manifestations in our patients with PNH support other data indicating abnormal neurodevelopment as part of the pathogenesis of 22q11.2DS.The location and cellular characteristics of PNH in 22q11.2DS overlaps with a group of migrating postnatal interneurons termed Arc cells, although more research is needed to confirm that PNH in 22q11.2DS represents Arc cells arrested in their migratory pathway.

Apert syndrome: magnetic resonance imaging (MRI) of associated intracranial anomalies

INTRODUCTION

Apert syndrome is one of the most common craniosynostosis syndrome caused by mutations in genes encoding fibroblast growth factor receptor 2 (FGFR2). It is characterized by multisuture craniosynostosis, midfacial hypoplasia, abnormal skull base development and syndactyly of all extremities. Apert syndrome is associated with a wide array of central nervous system (CNS) anomalies, possibly the cause of the common occurrence of mental deficiency in patients with Apert syndrome. These CNS anomalies can be broadly classified into two groups; (1) those that are primary malformations and (2) those that occur secondary to osseous deformity/malformation.

CONCLUSION

Familiarity with CNS anomalies associated with Apert syndrome is important to both clinicians and radiologist as it impacts on management and prognostication. Cognitive development of patients has been linked to associated CNS anomalies, timing of surgery and social aspects. These associated anomalies can be broadly classified into (1) those that are primary malformations and (2) those that occur secondary to osseous deformity/malformation, as illustrated in our review paper.

Upregulation of neurovascular communication through filamin abrogation promotes ectopic periventricular neurogenesis

Neuronal fate-restricted intermediate progenitors (IPs) are derived from the multipotent radial glia (RGs) and serve as the direct precursors for cerebral cortical neurons, but factors that control their neurogenic plasticity remain elusive. Here we report that IPs’ neuron production is enhanced by abrogating filamin function, leading to the generation of periventricular neurons independent of normal neocortical neurogenesis and neuronal migration. Loss of Flna in neural progenitor cells (NPCs) led RGs to undergo changes resembling epithelial-mesenchymal transition (EMT) along with exuberant angiogenesis that together changed the microenvironment and increased neurogenesis of IPs. We show that by collaborating with β-arrestin, Flna maintains the homeostatic signaling between the vasculature and NPCs, and loss of this function results in escalated Vegfa and Igf2 signaling, which exacerbates both EMT and angiogenesis to further potentiate IPs’ neurogenesis. These results suggest that the neurogenic potential of IPs may be boosted in vivo by manipulating Flna-mediated neurovascular communication.

DOI:http://dx.doi.org/10.7554/eLife.17823.001

Interstitial Lung Disease in Children Younger Than 2 Years

Childhood interstitial lung disease (chILD) represents a highly heterogeneous group of rare disorders associated with substantial morbidity and mortality. Although our understanding of chILD remains limited, important advances have recently been made, the most important being probably the appreciation that disorders that present in early life are distinct from those occurring in older children and adults, albeit with some overlap. chILD manifests with diffuse pulmonary infiltrates and nonspecific respiratory signs and symptoms, making exclusion of common conditions presenting in a similar fashion an essential preliminary step. Subsequently, a systematic approach to diagnosis includes a careful history and physical examination, computed tomography of the chest, and some or all of bronchoscopy with bronchoalveolar lavage, genetic testing, and if diagnostic uncertainty persists, lung biopsy. This review focuses on chILD presenting in infants younger than 2 years of age and discusses recent advances in the classification, diagnostic approach, and management of chILD in this age range. We describe novel genetic entities, along with initiatives that aim at collecting clinical data and biologic samples from carefully characterized patients in a prospective and standardized fashion. Early referral to expert centers and timely diagnosis may have important implications for patient management and prognosis, but effective therapies are often lacking. Following massive efforts, international collaborations among the key stakeholders are finally starting to be in place. These have allowed the setting up and conducting of the first randomized controlled trial of therapeutic interventions in patients with chILD.

Neuronal Heterotopias Affect the Activities of Distant Brain Areas and Lead to Behavioral Deficits

Neuronal heterotopia refers to brain malformations resulting from deficits of neuronal migration. Individuals with heterotopias show a high incidence of neurological deficits, such as epilepsy. More recently, it has come to be recognized that focal heterotopias may also show a range of psychiatric problems, including cognitive and behavioral impairments. However, because focal heterotopias are not always located in the brain areas responsible for the symptoms, the causal relationship between the symptoms and heterotopias remains elusive. In this study, we showed that mice with focal heterotopias in the somatosensory cortex generated by in utero electroporation exhibited spatial working memory deficit and low competitive dominance behavior, which have been shown to be closely associated with the activity of the medial prefrontal cortex (mPFC) in rodents. Analysis of the mPFC activity revealed that the immediate-early gene expression was decreased and the local field potentials of the mPFC were altered in the mice with heterotopias compared with the control mice. Moreover, activation of these ectopic and overlying sister neurons using the DREADD (designer receptor exclusively activated by designer drug) system improved the working memory deficits. These findings suggest that cortical regions containing focal heterotopias can affect distant brain regions and give rise to behavioral abnormalities. Significance statement: Recent studies reported that patients with heterotopias have a variety of clinical symptoms, such as cognitive disturbance, psychiatric symptoms, and autistic behavior. However, the causal relationship between the symptoms and heterotopias remains elusive. Here we showed that mice with focal heterotopias in the somatosensory cortex generated by in utero electroporation exhibited behavioral deficits that have been shown to be associated with the mPFC activity in rodents. The existence of heterotopias indeed altered the neural activities of the mPFC, and direct manipulation of the neural activity of the ectopic neurons and their sister neurons in the overlying cortex improved the behavioral deficit. Thus, our results indicate that focal heterotopias could affect the activities of distant brain areas and cause behavioral abnormalities.

Mechanical dynamics in live cells and fluorescence-based force/tension sensors

Three signaling systems play the fundamental roles in modulating cell activities: chemical, electrical, and mechanical. While the former two are well studied, the mechanical signaling system is still elusive because of the lack of methods to measure structural forces in real time at cellular and subcellular levels. Indeed, almost all biological processes are responsive to modulation by mechanical forces that trigger dispersive downstream electrical and biochemical pathways. Communication among the three systems is essential to make cells and tissues receptive to environmental changes. Cells have evolved many sophisticated mechanisms for the generation, perception and transduction of mechanical forces, including motor proteins and mechanosensors. In this review, we introduce some background information about mechanical dynamics in live cells, including the ubiquitous mechanical activity, various types of mechanical stimuli exerted on cells and the different mechanosensors. We also summarize recent results obtained using genetically encoded FRET (fluorescence resonance energy transfer)-based force/tension sensors; a new technique used to measure mechanical forces in structural proteins. The sensors have been incorporated into many specific structural proteins and have measured the force gradients in real time within live cells, tissues, and animals.

Association of mutations in FLNA with craniosynostosis

Mutations of FLNA, an X-linked gene that encodes the cytoskeletal protein filamin A, cause diverse and distinct phenotypes including periventricular nodular heterotopia and otopalatodigital spectrum disorders (OPDS). Craniofacial abnormalities associated with OPDS include supraorbital hyperostosis, down-slanting palpebral fissures and micrognathia; craniosynostosis was previously described in association with FLNA mutations in two individual case reports. Here we present four further OPDS subjects who have pathological FLNA variants and craniosynostosis, supporting a causal link. Together with the previously reported patients, frontometaphyseal dysplasia was the most common clinical diagnosis (four of six cases overall); five patients had multiple suture synostosis with the sagittal suture being the most frequently involved (also five patients). No genotype-phenotype correlation was evident in the distribution of FLNA mutations. This report highlights the need to consider a filaminopathy in the differential diagnosis of craniosynostosis, especially in the presence of atypical cranial or skeletal features.

MEK-ERK1/2-dependent FLNA overexpression promotes abnormal dendritic patterning in tuberous sclerosis independent of mTOR

Abnormal dendritic complexity is a shared feature of many neurodevelopmental disorders associated with neurological defects. Here, we found that the actin-crosslinking protein filamin A (FLNA) is overexpressed in tuberous sclerosis complex (TSC) mice, a PI3K-mTOR model of neurodevelopmental disease that is associated with abnormal dendritic complexity. Both under- and overexpression of FLNA in wild-type neurons led to more complex dendritic arbors in vivo, suggesting that an optimal level of FLNA expression is required for normal dendritogenesis. In Tsc1(null) neurons, knocking down FLNA in vivo prevented dendritic abnormalities. Surprisingly, FLNA overexpression in Tsc1(null) neurons was dependent on MEK1/2 but not mTOR activity, despite both pathways being hyperactive. In addition, increasing MEK-ERK1/2 activity led to dendritic abnormalities via FLNA, and decreasing MEK-ERK1/2 signaling in Tsc1(null) neurons rescued dendritic defects. These data demonstrate that altered FLNA expression increases dendritic complexity and contributes to pathologic dendritic patterning in TSC in an mTOR-independent, ERK1/2-dependent manner.

Classification and pathological characteristics of the cortical dysplasias

BACKGROUND

Focal cortical dysplasias (FCD) are a well-recognized cause of medically intractable epilepsy. They are defined as malformations of cortical development and are marked by abnormalities of cortical layering and neuronal differentiation and maturation. A number of classification approaches have been devised over the last four decades, indicating controversies surrounding issues of recognition, definition, and philosophical approach. More recent attempts have attempted to correlate morphologic phenotype with clinical or developmental parameters in order to provide a clinical relevance.

DISCUSSION

This short review provides an overview of the issues which account for the varied historical approaches to FCD classification and descriptions of gross pathologic findings associated with FCD and an overview of two more recently developed and widely used schema, the Palmini et al. (Neurology 62: S2-8, 2004) and the International League Against Epilepsy (ILAE) classifications Blumcke et al. Epilepsia 52: 158-174, 2011. The pathologic features of these two approaches will be reviewed and compared, including discussion of their limitations.

Ehlers-Danlos syndrome: a cause of epilepsy and periventricular heterotopia

PURPOSE

Ehlers-Danlos syndrome (EDS) comprises a variety of inherited connective tissue disorders that have been described in association with various neurological features. Until now the neurological symptoms have not been studied in detail; therefore, the aim of this review is to analyze the possible association between EDS, epilepsy and periventricular heterotopia (PH).

METHODS

We have carried out a critical review of all cases of epilepsy in EDS patients with and without PH.

RESULTS

Epilepsy is a frequent neurological manifestation of EDS; generally, it is characterized by focal seizures with temporo-parieto-occipital auras and the most common EEG findings epileptiform discharges and slow intermittent rhythm with delta-theta waves. Epilepsy in EDS patients is usually responsive to common antiepileptic therapy; very few cases of drug resistant focal epilepsy requested surgical treatment, with favorable results in terms of outcome. Epilepsy is the most common presenting neurological manifestation associated with PH in EDS patients. Abnormal anatomic circuitries (including heterotopic nodules) could generate epilepsy in patients with PH.

CONCLUSION

Among the principal neurological manifestations, epilepsy and PH have a considerable importance and can influence the long-term evolution of these patients. We hypothesize that PH may determine the epileptic manifestations in patients with EDS; much remains to be learnt about the relationships between nodules and the epileptic manifestations in EDS syndrome.

Germline mosaicism in X-linked periventricular nodular heterotopia

Background

X-linked periventricular nodular heterotopia is a disorder of neuronal migration resulting from mutations in the filamin A gene. This is an X-linked dominant condition where most affected patients are female and present with seizures. Extra–cerebral features such as cardiac abnormalities and thrombocytopenia have also been documented. Loss of function mutations in filamin A are predicted to result in prenatal lethality in males. Somatic mosaicism and mutations that lead to partial loss of function of the protein are hypothesized to explain viability of males reported in the literature. We report the first case of germline mosaicism involving a loss of function mutation in filamin A in a family where brain MRI, clinical exam, and mutation analysis is normal in both biological parents.

Case presentation

The index patient, a 39 year old female with normal development, had her first seizure at 24 years with no evidence of any precipitating factors. Brain MRI shows bilateral periventricular nodular heterotopia. She has thrombocytopenia and an echocardiogram at age 32 years revealed a mildly dilated aortic root and ascending aorta with mild aortic regurgitation. The second patient, the 36 year old younger sister of the index case, is currently healthy with no evidence of seizures or cardiac abnormalities. Her brain MRI is consistent with bilateral periventricular nodular heterotopia. The mother is healthy at 57 years of age with a normal brain MRI. The father is healthy at 59 years of age with a normal brain MRI. DNA sequencing of lymphocyte extracted DNA from the two sisters shows a c.2002C > T transition in exon 13 of filamin A resulting in a p.Gln668Ter mutation. This nonsense mutation was not detected in peripheral blood lymphocytes from the unaffected parents.

Conclusion

This report provides evidence for germline mosaicism in filamin A-associated periventricular nodular heterotopia. This case must now be considered when providing genetic counseling to families where a proband presents as an isolated case and parental investigations are unremarkable.

Bilateral posterior periventricular nodular heterotopia: a recognizable cortical malformation with a spectrum of associated brain abnormalities

BACKGROUND AND PURPOSE

Bilateral posterior PNH is a distinctive complex malformation with imaging features distinguishing it from classic bilateral PNH associated with FLNA mutations. The purpose of this study was to define the imaging features of posterior bilateral periventricular nodular heterotopia and to determine whether associated brain malformations suggest specific subcategories.

MATERIALS AND METHODS

We identified a cohort of 50 patients (31 females; mean age, 13 years) with bilateral posterior PNH and systematically reviewed and documented associated MR imaging abnormalities. Patients were negative for mutations of FLNA.

RESULTS

Nodules were often noncontiguous (n = 28) and asymmetric (n = 31). All except 1 patient showed associated developmental brain abnormalities involving a spectrum of posterior structures. A range of posterior fossa abnormalities affected the cerebellum, including cerebellar malformations and posterior fossa cysts (n = 38). Corpus callosum abnormalities (n = 40) ranged from mild dysplasia to agenesis. Posterior white matter volume was decreased (n = 22), and colpocephaly was frequent (n = 26). Most (n = 40) had associated cortical abnormalities ranging from minor to major (polymicrogyria), typically located in the cortex overlying the PNH. Abnormal Sylvian fissure morphology was common (n = 27), and hippocampal abnormalities were frequent (n = 37). Four family cases were identified-2 with concordant malformation patterns and 2 with discordant malformation patterns.

CONCLUSIONS

The associations of bilateral posterior PNH encompass a range of abnormalities involving brain structures inferior to the Sylvian fissures. We were unable to identify specific subgroups and therefore conceptualize bilateral posterior PNH as a continuum of infrasylvian malformations involving the posterior cerebral and hindbrain structures.

Peritrigonal and temporo-occipital heterotopia with corpus callosum and cerebellar dysgenesis

OBJECTIVE

To describe a homogeneous subtype of periventricular nodular heterotopia (PNH) as part of a newly defined malformation complex.

METHODS

Observational study including review of brain MRI and clinical findings of a cohort of 50 patients with PNH in the temporo-occipital horns and trigones, mutation analysis of the FLNA gene, and anatomopathologic study of a fetal brain.

RESULTS

There were 28 females and 22 males. All were sporadic with the exception of an affected mother and son. Epilepsy occurred in 62%, cerebellar signs in 56%, cognitive impairment in 56%, and autism in 12%. Seventy percent were referred within the 3rd year of life. Imaging revealed a normal cerebral cortex in 76% and abnormal cortical folding in 24%. In all patients the hippocampi were under-rotated and in 10% they merged with the heterotopia. Cerebellar dysgenesis was observed in 84% and a hypoplastic corpus callosum in 60%. There was no gender bias or uneven gender distribution of clinical and anatomic severity. No mutations of FLNA occurred in 33 individuals examined. Heterotopia in the fetal brain revealed cytoarchitectonic characteristics similar to those associated with FLNA mutations; cortical pathology was not typical of polymicrogyria. Cerebellar involvement was more severe and the hippocampi appeared simple and under-rotated.

CONCLUSIONS

This series delineates a malformation complex in which PNH in the trigones and occipito-temporal horns is associated with hippocampal, corpus callosum, and cerebellar dysgenesis. This subtype of PNH is distinct from classic PNH caused by FLNA mutations.

Development and dysgenesis of the cerebral cortex: malformations of cortical development

The cerebral cortex develops in several stages from a pseudostratified epithelium at 5 weeks to an essentially complete cortex at 47 weeks. Cortical connectivity starts with thalamocortical connections in the 3rd trimester only and continues until well after birth. Vascularity adapts to proliferation and connectivity. Malformations of cortical development are classified into disorders of specification, proliferation/apoptosis, migration, and organization. However, all processes are intermingled, as for example a dysplastic cell may migrate incompletely and not connect appropriately. However, this classification is convenient for didactic purposes as long as the complex interactions between the different processes are kept in mind.

FLNA genomic rearrangements cause periventricular nodular heterotopia

OBJECTIVE

To identify copy number variant (CNV) causes of periventricular nodular heterotopia (PNH) in patients for whom FLNA sequencing is negative.

METHODS

Screening of 35 patients from 33 pedigrees on an Affymetrix 6.0 microarray led to the identification of one individual bearing a CNV that disrupted FLNA. FLNA-disrupting CNVs were also isolated in 2 other individuals by multiplex ligation probe amplification. These 3 cases were further characterized by high-resolution oligo array comparative genomic hybridization (CGH), and the precise junctional breakpoints of the rearrangements were identified by PCR amplification and sequencing.

RESULTS

We report 3 cases of PNH caused by nonrecurrent genomic rearrangements that disrupt one copy of FLNA. The first individual carried a 113-kb deletion that removes all but the first exon of FLNA. A second patient harbored a complex rearrangement including a deletion of the 3' end of FLNA accompanied by a partial duplication event. A third patient bore a 39-kb deletion encompassing all of FLNA and the neighboring gene EMD. High-resolution oligo array CGH of the FLNA locus suggests distinct molecular mechanisms for each of these rearrangements, and implicates nearby low copy repeats in their pathogenesis.

CONCLUSIONS

These results demonstrate that FLNA is prone to pathogenic rearrangements, and highlight the importance of screening for CNVs in individuals with PNH lacking FLNA point mutations.

A meckelin-filamin A interaction mediates ciliogenesis

MKS3, encoding the transmembrane receptor meckelin, is mutated in Meckel-Gruber syndrome (MKS), an autosomal-recessive ciliopathy. Meckelin localizes to the primary cilium, basal body and elsewhere within the cell. Here, we found that the cytoplasmic domain of meckelin directly interacts with the actin-binding protein filamin A, potentially at the apical cell surface associated with the basal body. Mutations in FLNA, the gene for filamin A, cause periventricular heterotopias. We identified a single consanguineous patient with an MKS-like ciliopathy that presented with both MKS and cerebellar heterotopia, caused by an unusual in-frame deletion mutation in the meckelin C-terminus at the region of interaction with filamin A. We modelled this mutation and found it to abrogate the meckelin-filamin A interaction. Furthermore, we found that loss of filamin A by siRNA knockdown, in patient cells, and in tissues from Flna(Dilp2) null mouse embryos results in cellular phenotypes identical to those caused by meckelin loss, namely basal body positioning and ciliogenesis defects. In addition, morpholino knockdown of flna in zebrafish embryos significantly increases the frequency of dysmorphology and severity of ciliopathy developmental defects caused by mks3 knockdown. Our results suggest that meckelin forms a functional complex with filamin A that is disrupted in MKS and causes defects in neuronal migration and Wnt signalling. Furthermore, filamin A has a crucial role in the normal processes of ciliogenesis and basal body positioning. Concurrent with these processes, the meckelin-filamin A signalling axis may be a key regulator in maintaining correct, normal levels of Wnt signalling.

A glial origin for periventricular nodular heterotopia caused by impaired expression of Filamin-A

Periventricular nodular heterotopia (PH) is a human brain malformation caused by defective neuronal migration that results in ectopic neuronal nodules lining the lateral ventricles beneath a normal appearing cortex. Most affected patients have seizures and their cognitive level varies from normal to severely impaired. Mutations in the Filamin-A (or FLNA) gene are the main cause of PH, but the underlying pathological mechanism remains unknown. Although two FlnA knockout mouse strains have been generated, none of them showed the presence of ectopic nodules. To recapitulate the loss of FlnA function in the developing rat brain, we used an in utero RNA interference-mediated knockdown approach and successfully reproduced a PH phenotype in rats comparable with that observed in human patients. In FlnA-knockdown rats, we report that PH results from a disruption of the polarized radial glial scaffold in the ventricular zone altering progression of neural progenitors through the cell cycle and impairing migration of neurons into the cortical plate. Similar alterations of radial glia are observed in human PH brains of a 35-week fetus and a 3-month-old child, harboring distinct FLNA mutations not previously reported. Finally, juvenile FlnA-knockdown rats are highly susceptible to seizures, confirming the reliability of this novel animal model of PH. Our findings suggest that the disorganization of radial glia is the leading cause of PH pathogenesis associated with FLNA mutations. Rattus norvegicus FlnA mRNA (GenBank accession number FJ416060).

Monosomy1p36.3 and trisomy 19p13.3 in a child with periventricular nodular heterotopia

Monosomy 1p36 is a clinically recognizable syndrome that is considered to be the most common terminal deletion syndrome. It has characteristic clinical features that include craniofacial dysmorphism, congenital anomalies, hearing deficits, developmental delay, mental retardation, hypotonia, seizures, and brain anomalies. Brain anomalies in patients with 1p36 deletion are frequent but inconsistent. To date, 2 cases with monosomy 1p36 associated with periventricular nodular heterotopia (PNH) have been reported. We report a 2-month-old boy with multiple congenital anomalies; brain magnetic resonance imaging revealed PNH. The first 2 described cases were pure terminal deletions, whereas our patient carried unbalanced translocation due to an adjacent 1 segregation of a balanced maternal translocation, resulting in monosomy 1p36.3 and trisomy 19p13.3 identified by whole-genome array comparative genomic hybridization analysis. Our patient, with a smaller deletion that the 2 previously reported cases, can help narrow the critical region for PNH in association with the 1p36 deletion. Several potential candidate genes are discussed.

Drosophila Ten-m and filamin affect motor neuron growth cone guidance

The Drosophila Ten-m (also called Tenascin-major, or odd Oz (odz)) gene has been associated with a pair-rule phenotype. We identified and characterized new alleles of Drosophila Ten-m to establish that this gene is not responsible for segmentation defects but rather causes defects in motor neuron axon routing. In Ten-m mutants the inter-segmental nerve (ISN) often crosses segment boundaries and fasciculates with the ISN in the adjacent segment. Ten-m is expressed in the central nervous system and epidermal stripes during the stages when the growth cones of the neurons that form the ISN navigate to their targets. Over-expression of Ten-m in epidermal cells also leads to ISN misrouting. We also found that Filamin, an actin binding protein, physically interacts with the Ten-m protein. Mutations in cheerio, which encodes Filamin, cause defects in motor neuron axon routing like those of Ten-m. During embryonic development, the expression of Filamin and Ten-m partially overlap in ectodermal cells. These results suggest that Ten-m and Filamin in epidermal cells might together influence growth cone progression.

FlnA-null megakaryocytes prematurely release large and fragile platelets that circulate poorly

Filamin A (FlnA) is a large cytoplasmic protein that crosslinks actin filaments and anchors membrane receptors and signaling intermediates. FlnA(loxP) PF4-Cre mice that lack FlnA in the megakaryocyte (MK) lineage have a severe macrothrombocytopenia because of accelerated platelet clearance. Macrophage ablation by injection of clodronate-encapsulated liposomes increases blood platelet counts in FlnA(loxP) PF4-Cre mice and reveals the desintegration of FlnA-null platelets into microvesicles, a process that occurs spontaneously during storage. FlnA(loxP) PF4-Cre bone marrows and spleens have a 2.5- to 5-fold increase in MK numbers, indicating increased thrombopoiesis in vivo. Analysis of platelet production in vitro reveals that FlnA-null MKs prematurely convert their cytoplasm into large CD61(+) platelet-sized particles, reminiscent of the large platelets observed in vivo. FlnA stabilizes the platelet von Willebrand factor receptor, as surface expression of von Willebrand factor receptor components is normal on FlnA-null MKs but decreased on FlnA-null platelets. Further, FlnA-null platelets contain multiple GPIbα degradation products and have increased expression of the ADAM17 and MMP9 metalloproteinases. Together, the findings indicate that FlnA-null MKs prematurely release large and fragile platelets that are removed rapidly from the circulation by macrophages.

Podosomal proteins as causes of human syndromes: a role in craniofacial development?

Podosomes and invadopodia are actin-rich protrusions of the plasma membrane important for matrix degradation and cell migration. Most of the information in this field has been obtained in cancer cells, where the presence of invadopodia has been related to increased invasiveness and metastatic potential. The importance of the related podosome structure in other pathological or physiological processes that require cell invasion is relatively unexplored. Recent evidence indicates that essential components of podosomes are responsible for several human syndromes, some of which are characterized by serious developmental defects involving the craniofacial area, skeleton and heart, and very poor prognosis. Here we will review them and discuss the possible role of podosomes as a player in correct embryo development.

Ehlers-Danlos syndrome and neurological features: a review

Ehlers-Danlos Syndrome is a term that comprises a variety of inherited connective tissue disorders characterized primarily by skin hyperextensibility, joints hypermobility and excessive dislocations, easy bruisability, generalized fragility. If much is known about orthopedic or physiatric features of this syndrome, poor is known about the neurological ones. Thus neurological assessment is very important due to the possible various clinical manifestations in this syndrome.

Cerebral volumetric analysis over time in children with malformations of cortical development: a quantitative investigation

Malformations of cortical development are common neurological disorders characterized by disruptions in the normal development of cerebral gray and white matter during fetal life. We performed a quantitative, partly longitudinal investigation of cerebral volumes in a cohort of children with cortical malformations to investigate how their anatomical abnormalities change over time. Cortical malformation subjects showed volumetric curves that were comparable with those reported for healthy individuals, and reached peak cerebral volume, gray matter volume, and white matter volume at ages similar to those reported for healthy children. Volumes of heterotopic gray matter, however, demonstrated increases that were out of proportion to changes in cortical volume or caudate nucleus volume, suggesting that misplaced gray matter can have a unique pattern of maturation. Our findings demonstrate that overall brain growth in children with cortical malformations appears to mirror that of the healthy population, although malformed regions can show distinct growth patterns.

Filamin A regulates focal adhesion disassembly and suppresses breast cancer cell migration and invasion

The actin cross-linking protein filamin A reduces migration, invasion, and metastasis of breast cancer cells.

The actin cross-linking protein filamin A (FLNa) functions as a scaffolding protein and couples cell cytoskeleton to extracellular matrix and integrin receptor signaling. In this study, we report that FLNa suppresses invasion of breast cancer cells and regulates focal adhesion (FA) turnover. Two large progression tissue microarrays from breast cancer patients revealed a significant decrease of FLNa levels in tissues from invasive breast cancer compared with benign disease and in lymph node–positive compared with lymph node–negative breast cancer. In breast cancer cells and orthotopic mouse breast cancer models, down-regulation of FLNa stimulated cancer cell migration, invasion, and metastasis formation. Time-lapse microscopy and biochemical assays after FLNa silencing and rescue with wild-type or mutant protein resistant to calpain cleavage revealed that FLNa regulates FA disassembly at the leading edge of motile cells. Moreover, FLNa down-regulation enhanced calpain activity through the mitogen-activated protein kinase–extracellular signal-regulated kinase cascade and stimulated the cleavage of FA proteins. These results document a regulation of FA dynamics by FLNa in breast cancer cells.

FLNA p.V528M substitution is neither associated with bilateral periventricular nodular heterotopia nor with macrothrombocytopenia

Filamin A is encoded by the FLNA gene on chromosome Xq28 and functions in cross-linking actin filaments into orthogonal networks in the cortical cytoplasm. FLNA p.V528M was initially detected in a female autopsy case of X-linked bilateral periventricular nodular heterotopia (BPNH), a neuronal migration disorder characterized by subependymal nodules of gray matter. During our mutation analysis of FLNA in a boy with apparent X-linked thrombocytopenia, we detected the p.V528M variant. The patient, mother and sister, who were heterozygous for the substitution, did not have BPNH. We observed an allele frequency of 4.8% in healthy control Japanese, but did not observe the variant in Caucasian subjects. Hemizygous controls had a normal platelet count and size. We suggest that p.V528M is neither associated with BPNH nor with thrombocytopenia and giant platelets, and represents a functional polymorphism.

A mutation affecting the sodium/proton exchanger, SLC9A6, causes mental retardation with tau deposition

We have studied a family with severe mental retardation characterized by the virtual absence of speech, autism spectrum disorder, epilepsy, late-onset ataxia, weakness and dystonia. Post-mortem examination of two males revealed widespread neuronal loss, with the most striking finding being neuronal and glial tau deposition in a pattern reminiscent of corticobasal degeneration. Electron microscopic examination of isolated tau filaments demonstrated paired helical filaments and ribbon-like structures. Biochemical studies of tau demonstrated a preponderance of 4R tau isoforms. The phenotype was linked to Xq26.3, and further analysis identified an in-frame 9 base pair deletion in the solute carrier family 9, isoform A6 (SLC9A6 gene), which encodes sodium/hydrogen exchanger-6 localized to endosomal vesicles. Sodium/hydrogen exchanger-6 is thought to participate in the targeting of intracellular vesicles and may be involved in recycling synaptic vesicles. The striking tau deposition in our subjects reveals a probable interaction between sodium/proton exchangers and cytoskeletal elements involved in vesicular transport, and raises the possibility that abnormalities of vesicular targeting may play an important role in more common disorders such as Alzheimer's disease and autism spectrum disorders.

Novel cardiac findings in periventricular nodular heterotopia

Periventricular nodular heterotopia (PNH) is a set of neuronal migration disorders that occur during fetal development. Neurons in the brain fail to migrate from the lining of the lateral ventricles to the cortex of the brain. When the neurons fail to migrate, ectopic neuronal nodules form. Epilepsy is a common symptom of PNH. The majority of PNH cases appear to be due to mutations in filamin A, an X-linked gene. Most of the affected individuals are female because affected males typically die in utero. Filamin A anchors integral membrane proteins to the cytoskeleton by binding actin filaments in the cytoplasm. Both animal and human studies indicate that filamin A also plays a role in blood vessel development. In this report, we describe novel cardiac findings in an 18-month-old girl with PNH associated with a nonsense mutation in FLNA, including a dysplastic pulmonary valve and clefting of the mitral valve. These findings broaden the range of cardiac anomalies associated with filamin A mutations to include abnormality of the pulmonary valve and clefting of the mitral valve, consistent with a role for filamin A in valve leaflet development.

Impact of ethanol on the developing GABAergic system

Alcohol intake during pregnancy has a tremendous impact on the developing brain. Embryonic and early postnatal alcohol exposures have been investigated experimentally to elucidate the fetal alcohol spectrum disorders' (FASD) milieu, and new data have emerged to support a devastating effect on the GABAergic system in the adult and developing nervous system. GABA is a predominantly inhibitory neurotransmitter that during development excites neurons and orchestrates several developmental processes such as proliferation, migration, differentiation, and synaptogenesis. This review summarizes and brings new data on neurodevelopmental aspects of the GABAergic system with FASD in experimental telencephalic models.

Gray matter volumes and cognitive ability in the epileptogenic brain malformation of periventricular nodular heterotopia

Periventricular nodular heterotopia (PNH) is a brain malformation clinically characterized by the triad of epilepsy, normal intelligence, and dyslexia. We investigated the structure-function relationship between cerebral volumes and cognitive ability in this disorder by studying 12 subjects with PNH and 6 controls using volumetric analysis of high-resolution anatomical MRI and neuropsychological testing. Total cerebral volumes and specific brain compartment volumes (gray matter, white matter, and cerebrospinal fluid) in subjects with PNH were comparable to those in controls. There was a negative correlation between heterotopic gray matter volume and cortical gray matter volume. Cerebral and cortical volumes in PNH did not correlate with Full Scale IQ, unlike in normal individuals. Our findings support the idea that heterotopic nodules contain misplaced neurons that would normally have migrated to the cortex, and suggest that structural correlates of normal cognitive ability may be different in the setting of neuronal migration failure.

Reelin deficiency causes granule cell dispersion in epilepsy

Cortical migration defects are often associated with epilepsy. In mesial temporal lobe epilepsy (MTLE), granule cell dispersion (GCD), a migration defect of dentate granule cells, is frequently observed. Little is known how GCD develops and to which extent it contributes to the development of seizure activity. Since the reelin-deficient reeler mouse mutant shows a similar migration defect of dentate cells, we performed a series of studies investigating whether reelin deficiency is involved in GCD development. We show that in MTLE patients and in a mouse model of MTLE, the development of GCD correlates with a loss of the extracellular matrix protein reelin. In addition, we present evidence that GCD occurs in the absence of neurogenesis, thus representing a displacement of mature neurons due to a reelin deficiency. Accordingly, antibody blockade of reelin function in naïve, adult mice induced GCD. Finally, we show that GCD formation can be prevented by infusion of exogenous reelin. In summary, these studies show that in epilepsy reelin dysfunction causes GCD development and that reelin is important for the maintenance of layered structures in the adult brain.

Neuronal migration disorders

Lissencephaly-pachygyria-severe band heterotopia are diffuse neuronal migration disorders (NMDs) causing severe, global neurological impairment. Abnormalities of the LIS1, DCX, ARX, TUBA1A and RELN genes have been associated with these malformations. NMDs only affecting subsets of neurons, such as mild subcortical band heterotopia and periventricular heterotopia, cause neurological and cognitive impairment that vary from severe to mild deficits. They have been associated with abnormalities of the DCX, FLN1A, and ARFGEF2 genes. Polymicrogyria results from abnormal late cortical organization and is inconstantly associated with abnormal neuronal migration. Localized polymicrogyria has been associated with anatomo-specific deficits, including disorders of language and higher cognition. Polymicrogyria is genetically heterogeneous and only in a small minority of patients a definite genetic cause has been identified. Mutations of the GPR56 and SRPX2 genes have been related to isolated polymicrogyria. Focal migration abnormalities associated with abnormal cell types, such as focal cortical dysplasia, are highly epileptogenic and variably influence the functioning of the affected cortex. The functional consequences of abnormal neuronal migration are still poorly understood. Conservation of function in the malformed cortex, its atypical representation, and relocation outside the malformed area are all possible. Localization of function based on anatomic landmarks may not be reliable.

Cerebellar migration defects in aicardi syndrome: an extension of the neuropathological spectrum

The Aicardi syndrome is characterized by infantile spasms, corpus callosum agenesis, and chorioretinal lacunae and almost exclusively affects females (very rarely, 47, XXY males). The crucial genetic mishap likely occurs in the postzygotic stage, but the variable clinical phenotype among the approximately 450 known cases has not been explained. No consistent mutations or deletions exist among patients. We encountered a baby girl with early onset infantile spasms. She had left-sided cleft lip/palate, costovertebral defects, scoliosis, callosal agenesis, and microphthalmia. She expired at the age of 3 months of respiratory infection. On autopsy she had thoracic hemivertebrae with rib defects, bilateral microphthalmia, microcornea, posterior colobomata, abnormalities of the retinal pigment epithelium, absence of normal ganglion cells in the retina, gross asymmetry of the brain with cerebral polymicrogyria, total callosal agenesis, cerebral subcortical and subependymal nodular heterotopias, cerebellar nodular heterotopias, and tegmental/basal unilateral brainstem hypoplasia. Cerebellar and retinal migration defects have not been described before in Aicardi syndrome and may have had a bearing on this patient's eventual outcome.