ARF1 haploinsufficiency causes periventricular nodular heterotopia with variable clinical expressivity.

The primary anatomical defect leading to periventricular nodular heterotopia occurs within the neural progenitors along the neuroepithelial lining of the lateral ventricles and results from a defect in the initiation of neuronal migration, following disruption of the neuroependyma and impaired neuronal motility. Growing evidence indicates that the FLNA-dependent actin dynamics and regulation of vesicle formation and trafficking by activation of ADP-ribosylation factors (ARFs) can play an important role in this cortical malformation. We report the first inherited variant of ARF1 in a girl with intellectual disability and periventricular nodular heterotopia who inherited the variant from the father with previously undiagnosed single nodular heterotopia and mild clinical expression. Additionally, both patients presented some features suggestive of hypohidrotic ectodermal dysplasia. These clinical features showed similarities to those of three previously reported cases with ARF1 missense variants, confirming that haploinsufficiency of this gene causes a recognisable neurological disorder with abnormal neuronal migration and variable clinical expressivity.

Filamin A Mutations: A New Cause of Unexplained Emphysema in Adults?

Emphysema is a chronic respiratory disorder characterized by destruction of alveoli, usually due to cigarette smoking or exposure to noxious particles or gases. Dysfunction of proteins that are involved in lung development and maintenance, such as alpha-1 antitrypsin, also contributes to emphysema. Filamin A (FLNA) is an actin-binding protein involved in cytoskeleton reorganization. Mutations in the FLNA gene classically lead to abnormal neuronal migration and connective and vascular tissue anomalies. Pulmonary manifestations consist of a wide range of pulmonary disorders that occur during infancy. We report the first familial case of emphysema in non- and very low-smoking adults who carry a loss-of-function mutation of the FLNA gene. The identification of this new risk factor for emphysema encourages (1) screening, prevention and monitoring of pulmonary disorders in patients with FLNA mutation and (2) screening for FLNA mutation in patients with early-onset emphysema that is associated with low-smoking or vascular or connective tissue anomalies.

Stereo-EEG: Diagnostic and therapeutic tool for periventricular nodular heterotopia epilepsies.

OBJECTIVE: Periventricular nodular heterotopias (PNHs) are malformations of cortical development related to neuronal migration disorders, frequently associated with drug-resistant epilepsy (DRE). Stereo-electroencephalography (SEEG) is considered a very effective step of the presurgical evaluation, providing the recognition of the epileptogenic zone (EZ). At the same time, via the intracerebral electrodes it is possible to perform radiofrequency thermocoagulation (SEEG-guided RF-TC) with the aim of ablating and/or disrupting the EZ. The purpose of this study was to evaluate both the relationships between PNH and the EZ, and the efficacy of SEEG-guided RF-TC. METHODS: Twenty patients with DRE related to PNHs were studied. Inclusion criteria were the following: (1) patients with epilepsy and PNHs (unilateral or bilateral, single or multiple nodules) diagnosed on brain magnetic resonance imaging (MRI); (2) SEEG recordings available as part of the presurgical investigations, with at least one intracerebral electrode inside the heterotopia; (3) complete surgical workup with SEEG-guided RF-TC and/or with traditional neurosurgery, with a follow-up of at least 12 months. RESULTS: Complex and heterogenic epileptic networks were found in these patients. SEEG-guided RF-TC both into the nodules and/or the cortex was efficacious in the 76% of patients. Single or multiple, unilateral or bilateral PNHs are the most suitable for this procedure, whereas patients with PNHs associated with complex cortical malformations obtained excellent outcome only with traditional resective surgery. SIGNIFICANCE: Each patient had a specific epileptogenic network, independent from the number, size, or location of nodules and from the cortical malformation associated with. SEEG-guided RF-TC appears as a new and very effective diagnostic and therapeutic approach for DRE related to PNHs.

Familial periventricular nodular heterotopia, epilepsy and Melnick-Needles Syndrome caused by a single FLNA mutation with combined gain-of-function and loss-of-function effects.

BACKGROUND: Loss-of-function mutations of the FLNA gene cause a neuronal migration disorder defined as X-linked periventricular nodular heterotopia (PNH); gain-of-function mutations are associated with a group of X-linked skeletal dysplasias designed as otopalatodigital (OPD) spectrum. We describe a family in which a woman and her three daughters exhibited a complex phenotype combining PNH, epilepsy and Melnick-Needles syndrome (MNS), a skeletal disorder assigned to the OPD spectrum. All four individuals harboured a novel non-conservative missense mutation in FLNA exon 3. METHODS: In all affected family members, we performed mutation analysis of the FLNA gene, RT-PCR, ultradeep sequencing analysis in FLNA cDNAs and western blot in lymphocyte cells to further characterise the mutation. We also assessed the effects on RT-PCR products of treatment of patients' lymphocytes with cycloheximide, a nonsense mediated mRNA decay (NMD) inhibitor. RESULTS: We identified a novel c.622G>C change in FLNA exon 3, leading to the substitution of a highly conserved aminoacid (p.Gly208Arg). Gel electrophoresis and ultradeep sequencing revealed the missense mutation as well as retention of intron 3. Cycloheximide treatment demonstrated that the aberrant mRNA transcript-retaining intron 3 is subjected to NMD. Western blot analysis confirmed reduced FLNA levels in lymphocyte cells. CONCLUSIONS: The novel c.622G>C substitution leads to two aberrant FLNA transcripts, one of which carries the missense mutation, plus a longer transcript resulting from intron 3 retention. We propose that the exceptional co-occurrence of PNH and MNS, two otherwise mutually exclusive allelic phenotypes, is the consequence of a single mutational event resulting in co-occurring gain-of-function and loss-of-function effects.

Association of periventricular nodular heterotopia with posterior fossa cyst: a prenatal case series.

OBJECTIVE: The association of periventricular nodular heterotopia (PVNH) with posterior fossa cyst (PFC) is documented after birth. We report this association in a series of fetuses. METHODS: Eleven cases (7 females) of PVNH and PFC diagnosed at prenatal imaging were collected in this retrospective multicenter study. The patients were referred to tertiary centers for targeted ultrasonography (US) and Magnetic Resonance Imaging (MRI) following detection of PFC on routine US. Mutations of the filamin A gene (FLNA) were searched for (n = 6). Maternal brain MRI was performed (n = 8). Post-mortem or postnatal data were recorded. RESULTS: Targeted US was performed at a mean gestational age of 29 (range; 23-35) weeks and identified PVNH in 4 cases. At MRI, performed at a mean gestational age of 31 (range; 29-35) weeks, PVNH and PFC were visible in all cases. Those findings were confirmed by postnatal MRI (n = 3), autopsy (n = 7) and/or post-mortem MRI (n = 2) or US (n = 1). Maternal brain MRI showed PVNH in one case. A de novo FLNA mutation was found in four cases. CONCLUSION: We describe a series of PVNH and PFC in fetuses, which underlines the importance of searching for PVNH when PFC is identified at prenatal US. © 2014 John Wiley & Sons, Ltd.

Bilateral periventricular nodular heterotopia with megalencephaly: a case report.

Bilateral periventricular nodular heterotopia is a neuronal migration disorder characterized by gray matter cellular rests in the periventricular regions. Megalencephaly has not been reported in children with bilateral periventricular nodular heterotopia. No other disorder with a similar phenotype has been reported. Here we report the case of a 5-year-old Japanese boy with bilateral periventricular nodular heterotopia and megalencephaly. Relative macrocephaly was evident at birth, and bilateral periventricular nodular heterotopia and megalencephaly were noted on magnetic resonance imaging (MRI). However, no hydrocephalus or indication of cerebral cortical dysplasia was seen. A mild intellectual disability was present, but the patient had no history of seizures. Genetic analysis revealed no mutation on the capillary sequences for FLNA, and no pathogenic abnormalities were evident on array comparative genomic hybridization. This case could represent a new disease entity: bilateral periventricular nodular heterotopia with megalencephaly.

Prenatal diagnosis of frontonasal dysplasia associated with bilateral periventricular nodular heterotopia.

Frontonasal dysplasia is an etiologically heterogeneous development alteration including a set of anomalies affecting the eyes, forehead, and nose as a result of a malformation of the frontonasal elevation. It could occur either in isolation or as part of a syndrome such as frontonasal dysplasia associated with periventricular heterotopia. Our goal is to document the first clinical case of prenatal diagnosis for frontonasal dysplasia associated with periventricular heterotopia by fetal magnetic resonance imaging (MRI) at weeks 19.5 and 29 and postnatal MRI. In conclusion, the presence of frontonasal dysplasia in a prenatal ultrasonography should always be followed by a fetal MRI with routine screening for periventricular nodular heterotopias so as to establish a more adequate prognosis for the family.

Periventricular nodular heterotopia on prenatal ultrasound and magnetic resonance imaging.

OBJECTIVES: To describe the prenatal ultrasound and magnetic resonance imaging (MRI) findings suggestive of periventricular nodular heterotopia (PNH). METHODS: This retrospective case series included fetuses referred to our institution for brain MRI between 2007 and 2012, which were diagnosed with PNH and confirmed by postnatal MRI or autopsy. The type of PNH, associated ventriculomegaly and associated malformations are reported. RESULTS: We included 11 fetuses (nine female, two male) with a mean gestational age at diagnosis of 31 (range, 23-34) weeks. PNH lesions were small and diffuse (n = 7), large and multiple (n = 1) or single (n = 3). A targeted ultrasound examination performed before fetal MRI missed the diagnosis in four cases (one diffuse and three single); a further ultrasound examination performed after MRI diagnosed PNH in two of these four cases. Ventriculomegaly was present in six cases (four unilateral and two bilateral). PNH appeared in all cases as nodules of intermediate echogenicity protruding into the ventricular lumen. In all cases of diffuse PNH, the frontal horns and bodies of the lateral ventricles appeared square in shape on coronal view, with irregular borders on axial view. Associated cerebral malformations were observed in seven cases and included corpus callosal agenesis (n = 4, with additional malformations in two) and retrocerebellar cyst (n = 3). Extracerebral malformations were also present in two cases. Maternal MRI was performed in five of the six cases of isolated small and diffuse PNH in female fetuses, and demonstrated PNH in two of these. CONCLUSION: PNH is underdiagnosed at prenatal ultrasound, even on targeted scans. Irregular ventricular borders on axial view and irregular square-shaped lateral ventricles on coronal view are suggestive of PNH at prenatal ultrasound.

Whole-exome sequencing of a unique brain malformation with periventricular heterotopia, cingulate polymicrogyria and midbrain tectal hyperplasia.

We report a case of an infant with unique and unreported combinations of brain anomalies. The patient showed distinctive facial findings, severe delay in psychomotor development, cranial nerve palsy and seizures. Brain magnetic resonance imaging performed at 5 days of age revealed complex brain malformations, including heterotopia around the mesial wall of lateral ventricles, dysmorphic cingulate gyrus, and enlarged midbrain tectum. The patient unexpectedly died at 13 months of age. Postmortem pathological findings included a polymicrogyric cingulate cortex, periventricular nodular heterotopia, basal ganglia and thalamic anomalies, and dysmorphic midbrain tectum. Potential candidate genes showed no abnormalities by traditional PCR-based sequencing. Whole-exome sequencing confirmed the presence of novel gene variants for filamin B (FLNB), guanylate binding protein family member 6, and chromosome X open reading frame 59, which adapt to the autosomal recessive mode or X-linked recessive mode. Although immunohistochemical analysis confirmed the expression of FLNB protein in the vessel walls and white matter in autopsied specimens, there may be functional relevance of the compound heterozygous FLNB variants during brain development.

Asymmetric polymicrogyria and periventricular nodular heterotopia due to mutation in ARX.

Mutations in the ARX gene, at Xp22.3, cause several disorders, including infantile spasms, X-linked lissencephaly with abnormal genitalia (XLAG), callosal agenesis and isolated intellectual disability. Genotype/phenotype studies suggested that polyalanine tract expansion is associated with non-malformative phenotypes, while missense and nonsense mutations cause cerebral malformations, however, patients with structural normal brain and missense mutations have been reported. We report on a male patient born with cleft lip and palate who presented with infantile spasms and hemiplegia. MRI showed agenesis of corpus callosum (ACC), an interhemispheric cyst, periventricular nodular heterotopia (PVNH), and extensive left frontal polymicrogyria (PMG). Sequencing of the ARX gene in the patient identified a six basepair insertion (c.335ins6, exon 2). The insertion leads to a two-residue expansion of the first polyalanine tract and was described previously in a family with non-syndromic X-linked mental retardation. To our knowledge, ARX mutation causing PMG and PVNH is unique, but the spasms and ACC are common in ARX mutations. Clinicians should be aware of the broad clinical range of ARX mutations, and further studies are necessary to investigate the association with PMG and PVNH and to identify possible modifying factors.

Reproducibility of interictal EEG-fMRI results in patients with epilepsy.

PURPOSE: Combined electroencephalography (EEG) and functional MRI (EEG-fMRI) can be useful in the evaluation of epilepsy patients. The reproducibility of EEG-fMRI findings needs to be established to consider it as a clinically valuable method. We addressed the intrasubject reproducibility of EEG-fMRI and the possible superiority of higher magnetic field strength in patients who were scanned twice. METHODS: Fifteen patients were studied: Seven had one 1.5T and one 3T scan and eight had two 3T EEG-fMRI studies. Equal numbers of events of the same interictal epileptic discharge (IED) were included, and IED-related blood oxygenation level dependent (BOLD) results were compared. KEY FINDINGS: In 1.5T-3T comparisons, five patients had BOLD responses in both studies, but in four there was a better response (higher maximum t-score and larger cluster) in 3T studies. One patient had a BOLD response in the 3T study only. The remaining patient had no BOLD response in either study. In 3T-3T comparisons, results were reproducible in five of eight patients, and one patient had no response in both studies. The two remaining patients had previous extensive surgery and extremely frequent IEDs. Some of the reproduced patterns in other patients, however, differed in terms of maximum t-score and cluster size. SIGNIFICANCE: EEG-fMRI appears to provide reasonable reproducibility, although repeated studies may show differences. The absence of BOLD response seems to be reproducible as well. EEG-fMRI results tend to benefit from higher field scanners (3T over 1.5T). Further studies are needed to determine if reproducibility depends on specific clinical, electrographic, or anatomic findings.