Lissencephaly in an epilepsy cohort: Molecular, radiological and clinical aspects

Characterization of the Epileptogenic Phenotype and Response to Antiseizure Medications in Lissencephaly Patients

BACKGROUND

 Patients with lissencephaly typically present with severe psychomotor retardation and drug-resistant seizures. The aim of this study was to characterize the epileptic phenotype in a genotypically and radiologically well-defined patient cohort and to evaluate the response to antiseizure medication (ASM). Therefore, we retrospectively evaluated 47 patients of five genetic forms (LIS1/PAFAH1B1, DCX, DYNC1H1, TUBA1A, TUBG1) using family questionnaires, standardized neuropediatric assessments, and patients' medical reports.

RESULTS

 All but two patients were diagnosed with epilepsy. Median age at seizure onset was 6 months (range: 2.1-42.0), starting with epileptic spasms in 70%. Standard treatment protocols with hormonal therapy (ACTH or corticosteroids) and/or vigabatrin were the most effective approach for epileptic spasms, leading to seizure control in 47%. Seizures later in the disease course were most effectively treated with valproic acid and lamotrigine, followed by vigabatrin and phenobarbital, resulting in seizure freedom in 20%. Regarding psychomotor development, lissencephaly patients presenting without epileptic spasms were significantly more likely to reach various developmental milestones compared to patients with spasms.

CONCLUSION

 Classic lissencephaly is highly associated with drug-resistant epilepsy starting with epileptic spasms in most patients. The standard treatment protocols for infantile epileptic spasms syndrome lead to freedom from seizures in around half of the patients. Due to the association of epileptic spasms with an unfavorable course of psychomotor development, early and reliable diagnosis and treatment of spasms should be pursued. For epilepsies occurring later in childhood, ASM with valproic acid and lamotrigine, followed by vigabatrin and phenobarbital, appears to be most effective.

Novel copy number variations and phenotypes of infantile epileptic spasms syndrome

We summarize the copy number variations (CNVs) and phenotype spectrum of infantile epileptic spasms syndrome (IESS) in a Chinese cohort. The CNVs were identified by genomic copy number variation sequencing. The CNVs and clinical data were analyzed. 74 IESS children with CNVs were enrolled. 35 kinds of CNVs were identified. There were 11 deletions and 5 duplications not reported previously in IESS, including 2 CNVs not reported in epilepsy. 87.8% were de novo, 9.5% were inherited from mother and 2.7% from father. Mosaicism occurred in one patient with Xq21.31q25 duplication. 16.2% (12/74) were 1p36 deletion, and 20.3% (15/74) were 15q11-q13 duplication. The age of seizure onset ranged from 17 days to 24 months. Seizure types included epileptic spasms, focal seizures, tonic seizures, and myoclonic seizures. All patients displayed developmental delay. Additional features included craniofacial anomaly, microcephaly, congenital heart defects, and hemangioma. 29.7% of patients were seizure-free for more than 12 months, and 70.3% still had seizures after trying 2 or more anti-seizure medications. In conclusion, CNVs is a prominent etiology of IESS. 1p36 deletion and 15q duplication occurred most frequently. CNV detection should be performed in patients with IESS of unknown causes, especially in children with craniofacial anomalies and microcephaly.

Clinical features and genotype-phenotype correlations in epilepsy patients with de novo DYNC1H1 variants

OBJECTIVE

DYNC1H1 variants are involved on a disease spectrum from neuromuscular disorders to neurodevelopmental disorders. DYNC1H1-related epilepsy has been reported in small cohorts. We dissect the electroclinical features of 34 patients harboring de novo DYNC1H1 pathogenic variants, identify subphenotypes on the DYNC1H1-related epilepsy spectrum, and compare the genotype-phenotype correlations observed in our cohort with the literature.

METHODS

Patients harboring de novo DYNC1H1 pathogenic variants were recruited through international collaborations. Clinical data were retrospectively collected. Latent class analysis was performed to identify subphenotypes. Multivariable binary logistic regression analysis was applied to investigate the association with DYNC1H1 protein domains.

RESULTS

DYNC1H1-related epilepsy presented with infantile epileptic spasms syndrome (IESS) in 17 subjects (50%), and in 25% of these individuals the epileptic phenotype evolved into Lennox-Gastaut syndrome (LGS). In 12 patients (35%), focal onset epilepsy was defined. In two patients, the epileptic phenotype consisted of generalized myoclonic epilepsy, with a progressive phenotype in one individual harboring a frameshift variant. In approximately 60% of our cohort, seizures were drug-resistant. Malformations of cortical development were noticed in 79% of our patients, mostly on the lissencephaly-pachygyria spectrum, particularly with posterior predominance in a half of them. Midline and infratentorial abnormalities were additionally reported in 45% and 27% of subjects. We have identified three main classes of subphenotypes on the DYNC1H1-related epilepsy spectrum.

SIGNIFICANCE

We propose a classification in which pathogenic de novo DYNC1H1 variants feature drug-resistant IESS in half of cases with potential evolution to LGS (Class 1), developmental and epileptic encephalopathy other than IESS and LGS (Class 2), or less severe focal or genetic generalized epilepsy including a progressive phenotype (Class 3). We observed an association between stalk domain variants and Class 1 phenotypes. The variants p.Arg309His and p.Arg1962His were common and associated with Class 1 subphenotype in our cohort. These findings may aid genetic counseling of patients with DYNC1H1-related epilepsy.

Total callosotomy ameliorates epileptic activity and improves cognitive function in a patient with Miller-Dieker syndrome

Miller-Dieker syndrome (MDS) is characterized by facial abnormalities and lissencephaly and is caused by a microdeletion in the region containing the LIS1 gene at chromosome 17p13.3. We report a case in which postnatal neuroimaging revealed severe lissencephaly. A 9-month-old boy presented with infantile spasms syndrome. Because of the refractory course of seizures and continued poor vitality, total corpus callosotomy was performed at 28 months of age. Intraoperative electroencephalogram (EEG) showed that the bilateral synchronous epileptiform discharges disappeared immediately after the disconnection. Postoperatively, the epileptic spasms (ES) in clusters disappeared, and single ES followed by focal seizures became the main symptom. The patient smiled more and became more responsive to stimuli. Postoperative scalp interictal EEG showed desynchronized multifocal spike and wave discharges with a marked decrease in the bilateral synchronous spike and wave discharges. Our findings suggest that the corpus callosum is involved in the mechanism ES in clusters in MDS-associated lissencephaly, and total callosotomy could be a therapeutic option.

Infantile epileptic spasms syndrome in a child with lissencephaly associated with de novo PAFAH1B1 variant and coincidental CMV infection

Type 1 lissencephaly is a brain malformation characterized by agyria and pachygyria and is known to be caused by congenital infections and genetic variations. Here we present a case of a 4-month-old female with new onset infantile epileptic spasms syndrome (IESS) with initial etiology concerned for congenital cytomegalovirus (cCMV) due to a positive urine CMV PCR and maternal viral syndrome during pregnancy. Her brain MRI was significant for type 1 lissencephaly without other radiographical features of cCMV. The patient initially responded to high dose Prednisolone but had relapse of spasms at 9-month-old and required an ACTH course. She later developed generalized tonic seizures and focal impaired awareness seizures. Subsequent whole exome sequencing (WES) trio revealed a de novo PAFAH1B1 (c.405G > A, p.W135*) heterozygous nonsense variant which is pathogenic and thus solved the diagnostic puzzle. This case demonstrates that the absence of cCMV stigmata should raise concern for alternative etiology in cases of lissencephaly and the importance of genetic evaluation for subsequent management and family counseling.

Experimental models of human cortical malformations: from mammals to 'acortical' zebrafish

Human neocortex controls and integrates cognition, emotions, perception and complex behaviors. Aberrant cortical development can be triggered by multiple genetic and environmental factors, causing cortical malformations. Animal models, especially rodents, are a valuable tool to probe molecular and physiological mechanisms of cortical malformations. Complementing rodent studies, the zebrafish (Danio rerio) is an important model organism in biomedicine. Although the zebrafish (like other fishes) lacks neocortex, here we argue that this species can still be used to model various aspects and brain phenomena related to human cortical malformations. We also discuss novel perspectives in this field, covering both advantages and limitations of using mammalian and zebrafish models in cortical malformation research. Summarizing mounting evidence, we also highlight the importance of translationally-relevant insights into the pathogenesis of cortical malformations from animal models, and discuss future strategies of research in the field.

DCX variants in two unrelated Chinese families with subcortical band heterotopia: Two case reports and review of literature

Introduction

Subcortical band heterotopia (SBH) is a rare brain developmental malformation caused by deficient neuronal migration during embryogenesis. Published literature on pediatric SBH cases caused by DCX mutations is limited.

Methods

The detailed clinical and genetic features of two pediatric SBH with DCX mutations were analyzed. The available literature on DCX mutations was reviewed.

Results

Both patients were girls with varying degrees of developmental delay. Patient 1 was short in stature with peculiar facial features. Patient 2 had an early seizure onset and developed drug-resistant epilepsy. Whole-exome sequencing (WES) revealed two de novo heterozygous variants of DCX (NM_178153.3), including a novel missense variant of c.568A > G (p.K190E) in P1 and a reported nonsense variant of c.814C > T (p.R272*) in P2. We reviewed all the available literature regarding DCX mutations. A total of 153 different mutations have been reported, with the majority of 99 (64.7 %) being missense mutations.

Conclusion

Our study expanded the mutational spectrum of DCX, which has important implications for the study of genotype-phenotype correlations. Furthermore, it provided insights to better understand SBH and genetic counseling.

Molecular analysis and prenatal diagnosis of seven Chinese families with genetic epilepsy

Introduction

Genetic epilepsy is a large group of clinically and genetically heterogeneous neurological disorders characterized by recurrent seizures, which have a clear association with genetic defects. In this study, we have recruited seven families from China with neurodevelopmental abnormalities in which epilepsy was a predominant manifestation, aiming to elucidate the underlying causes and make a precise diagnosis for the cases.

Methods

Whole-exome sequencing (WES) combined with Sanger sequencing was used to identify the causative variants associated with the diseases in addition to essential imaging and biomedical examination.

Results

A gross intragenic deletion detected in MFSD8 was investigated via gap-polymerase chain reaction (PCR), real-time quantitative PCR (qPCR), and mRNA sequence analysis. We identified 11 variants in seven genes (ALDH7A1, CDKL5, PCDH19, QARS1, POLG, GRIN2A, and MFSD8) responsible for genetic epilepsy in the seven families, respectively. A total of six variants (c.1408T>G in ALDH7A1, c.1994_1997del in CDKL5, c.794G>A in QARS1, c.2453C>T in GRIN2A, and c.217dup and c.863+995_998+1480del in MFSD8) have not yet been reported to be associated with diseases and were all evaluated to be pathogenic or likely pathogenic according to the American College of Medical Genetics and Genomics (ACMG) guidelines.

Methods

Based on the molecular findings, we have associated the intragenic deletion in MFSD8 with the mutagenesis mechanism of Alu-mediated genomic rearrangements for the first time and provided genetic counseling, medical suggestions, and prenatal diagnosis for the families. In conclusion, molecular diagnosis is crucial to obtain improved medical outcomes and recurrence risk evaluation for genetic epilepsy.

Case report: Genotype and phenotype of DYNC1H1-related malformations of cortical development: a case report and literature review

Background

Mutations in the dynein cytoplasmic 1 heavy chain 1 (DYNC1H1) gene are linked to malformations of cortical development (MCD), which may be accompanied by central nervous system (CNS) manifestations. Here, we present the case of a patient with MCD harboring a variant of DYNC1H1 and review the relevant literature to explore genotype-phenotype relationships.

Case presentation

A girl having infantile spasms, was unsuccessfully administered multiple antiseizure medications and developed drug-resistant epilepsy. Brain magnetic resonance imaging (MRI) at 14 months-of-age revealed pachygyria. At 4 years-of-age, the patient exhibited severe developmental delay and mental retardation. A de novo heterozygous mutation (p.Arg292Trp) in the DYNC1H1 gene was identified. A search of multiple databases, including PubMed and Embase, using the search strategy DYNC1H1 AND [malformations of cortical development OR seizure OR intellectual OR clinical symptoms] up to June 2022, identified 129 patients from 43 studies (including the case presented herein). A review of these cases showed that patients with DYNC1H1-related MCD had higher risks of epilepsy (odds ratio [OR] = 33.67, 95% confidence interval [CI] = 11.59, 97.84) and intellectual disability/developmental delay (OR = 52.64, 95% CI = 16.27, 170.38). Patients with the variants in the regions encoding the protein stalk or microtubule-binding domain had the most prevalence of MCD (95%).

Conclusion

MCD, particularly pachygyria, is a common neurodevelopmental disorder in patients with DYNC1H1 mutations. Literature searches reveales that most (95%) patients who carried mutations in the protein stalk or microtubule binding domains exhibited DYNC1H1-related MCD, whereas almost two-thirds of patients (63%) who carried mutations in the tail domain did not display MCD. Patients with DYNC1H1 mutations may experience central nervous system (CNS) manifestations due to MCD.

DYNC1H1-related epilepsy: Genotype-phenotype correlation

AIM

To explore the phenotypic spectrum and refine the genotype-phenotype correlation of DYNC1H1-related epilepsy.

METHOD

The clinical data of 15 patients with epilepsy in our cohort and 50 patients with epilepsy from 24 published studies with the DYNC1H1 variants were evaluated.

RESULTS

In our cohort, 13 variants were identified from 15 patients (seven males, eight females). Twelve variants were de novo and seven were new. Age at seizure onset ranged from 3 months to 4 years 5 months (median age 1 year). Common seizure types were epileptic spasms, focal seizures, tonic seizures, and myoclonic seizures. Mild-to-severe developmental delay was present in all patients. Six patients were diagnosed with West syndrome and one was diagnosed with epileptic encephalopathy with continuous spikes and waves during slow sleep (CSWS). Collectively, in our cohort and published studies, 17% had ophthalmic diseases, 31% of variants were located in the stalk domain, and 92% patients with epilepsy had a malformation of cortical development (MCD).

INTERPRETATION

The phenotypes of DYNC1H1-related epilepsy included multiple seizure types; the most common epileptic syndrome was West syndrome. CSWS is a new phenotype of DYNC1H1-related epilepsy. One-third of the variants in patients with epilepsy were located in the stalk domain. Most patients had a MCD and developmental delay.

WHAT THIS PAPER ADDS

Nearly 40% of patients with DYNC1H1 variants had epilepsy. Ninety-two percent of patients with DYNC1H1-related epilepsy had malformation of cortical development. More than 10% of patients with DYNC1H1-related epilepsy were diagnosed with West syndrome. Continuous spikes and waves during slow sleep could be a new phenotype of DYNC1H1 variants. One-third of the variants in patients with epilepsy were located in the stalk domain.

Forward Genetics-Based Approaches to Understanding the Systems Biology and Molecular Mechanisms of Epilepsy

Epilepsy is a highly prevalent, severely debilitating neurological disorder characterized by seizures and neuronal hyperactivity due to an imbalanced neurotransmission. As genetic factors play a key role in epilepsy and its treatment, various genetic and genomic technologies continue to dissect the genetic causes of this disorder. However, the exact pathogenesis of epilepsy is not fully understood, necessitating further translational studies of this condition. Here, we applied a computational in silico approach to generate a comprehensive network of molecular pathways involved in epilepsy, based on known human candidate epilepsy genes and their established molecular interactors. Clustering the resulting network identified potential key interactors that may contribute to the development of epilepsy, and revealed functional molecular pathways associated with this disorder, including those related to neuronal hyperactivity, cytoskeletal and mitochondrial function, and metabolism. While traditional antiepileptic drugs often target single mechanisms associated with epilepsy, recent studies suggest targeting downstream pathways as an alternative efficient strategy. However, many potential downstream pathways have not yet been considered as promising targets for antiepileptic treatment. Our study calls for further research into the complexity of molecular mechanisms underlying epilepsy, aiming to develop more effective treatments targeting novel putative downstream pathways of this disorder.

Missed diagnosis of lissencephaly after prenatal diagnosis: A case report

RATIONALE

Lissencephaly (LIS) is a rare and serious cortical malformation characterized by a smooth or nearly smooth brain surface. With the progress of molecular genetics, platelet-activating factor acetylhydrolase brain isoform Ib is the most frequent type during the fetal period. Here, we report an infant with LIS who was missed although undergoing prenatal diagnosis. We aim to share our experiences and lessons.

PATIENT CONCERNS

A 2-month-old male infant presented recurrent convulsions. Karyotype and copy number variation sequencing were conducted to be normal at the 23-week gestation because of bipedal varus and ventricular septal defect (2.3 mm). After birth, he suffered from epilepsy confirmed by video electroencephalogram exam, meanwhile, computed tomography and magnetic resonance imaging revealed pachygyria. The infant was diagnosed with LIS carrying a de-novo mutation c.817 C > T (p.Arg273 Ter,138) in exon 8 of platelet-activating factor acetylhydrolase brain isoform Ib (NM_000430) detected by whole-exome sequencing.

DIAGNOSES

Based on the clinical characteristics, imaging, and genetic test findings, the infant was diagnosed with LIS.

INTERVENTIONS

The patient was treated with topiramate and dose was adjusted according to the seizure frequency.

OUTCOMES

The infant had recurrent seizures. The muscle tone of his extremities increased, and he could not look up or turn over actively at the age of 6 months.

LESSONS

Comprehensive evaluation of a multi-disciplinary team should be recommended for patients with epilepsy and cerebral hypoplasia. Individuals with LIS during the fetal period might be missed due to atypical features. In fetuses with structural abnormalities, if karyotype and copy number variation sequencing are both normal, whole-exome sequencing may be an effective complementary means to detect pathogenic variants.

Clinical and Surgical Approach for Cerebral Cortical Dysplasia

The present article describes pathophysiological and clinical aspects of congenital malformations of the cerebral tissue (cortex and white matter) that cause epilepsy and very frequently require surgical treatment. A particular emphasis is given to focal cortical dysplasias, the most common pathology among these epilepsy-related malformations. Specific radiological and surgical features are also highlighted, so a thorough overview of cortical dysplasias is provided.

DYNC1H1 variant associated with epilepsy: Expanding the phenotypic spectrum

DYNC1H1 variants are associated with peripheral neuronal dysfunction and brain morphology abnormalities resulting in neurodevelopmental delay. However, few studies have focused on the association between DYNC1H1 variants and epilepsy. Herein, we report a case of drug-resistant focal epilepsy associated with a pathogenic variant of DYNC1H1. We further summarized the clinical, genetic, and neuroimaging characteristics of patients with DYNC1H1 variant-associated epilepsy from the relevant literature. This report expands the phenotypic spectrum of DYNC1H1-related disorder to include early-onset epilepsy, which is frequently associated with neurodevelopmental delay and intellectual disability, malformations of cortical development, and neuromuscular, ophthalmic, and orthopedic involvement.

Functions of G protein-coupled receptor 56 in health and disease

Human G protein-coupled receptor 56 (GPR56) is encoded by gene ADGRG1 from chromosome 16q21 and is homologously encoded in mice, at chromosome 8. Both 687 and 693 splice forms are present in humans and mice. GPR56 has a 381 amino acid-long N-terminal extracellular segment and a GPCR proteolysis site upstream from the first transmembrane domain. GPR56 is mainly expressed in the heart, brain, thyroid, platelets, and peripheral blood mononuclear cells. Accumulating evidence indicates that GPR56 promotes the formation of myelin sheaths and the development of oligodendrocytes in the cerebral cortex of the central nervous system. Moreover, GPR56 contributes to the development and differentiation of hematopoietic stem cells, induces adipogenesis, and regulates the function of immune cells. The lack of GPR56 leads to nervous system dysfunction, platelet disorders, and infertility. Abnormal expression of GPR56 is related to the malignant transformation and tumor metastasis of several cancers including melanoma, neuroglioma, and gastrointestinal cancer. Metabolic disorders and cardiovascular diseases are also associated with dysregulation of GPR56 expression, and GPR56 is involved in the pharmacological resistance to some antidepressant and cancer drug treatments. In this review, the molecular structure, expression profile, and signal transduction of GPR56 are introduced, and physiological and pathological functions of GRP56 are comprehensively summarized. Attributing to its significant biological functions and its long N-terminal extracellular region that interacts with multiple ligands, GPR56 is becoming an attractive therapeutic target in treating neurological and hematopoietic diseases.

Whole-exome sequencing identifies a novel de novo variant in DYNC1H in a patient with intractable epilepsy

DYNC1H1 variants are associated with broad phenotypes including Charcot-Marie-Tooth disease, spinal muscular atrophy, and mental retardation. However, DYNC1H1 variants related intractable epilepsy have not yet been described in detail so far. Herein, we describe the detailed clinical manifestations of a female patient, carrying a novel de novo variant in DYNC1H1 (p.H311Y), who presented with malformation of cortical development (MCD), refractory epilepsy, intellectual disability, and lower motor neuron disease. We provide a review of previously reported patients who presented with epilepsy associated with DYNC1H1 variants. Of the patients with epilepsy, the DYNC1H1 variants were distributed, on average, in the tail, linker, and motor domains, rather than being mainly distributed in the tail domain as previously reported.

Complementing the phenotypical spectrum of TUBA1A tubulinopathy and its role in early-onset epilepsies

TUBA1A tubulinopathy is a rare neurodevelopmental disorder associated with brain malformations as well as early-onset and intractable epilepsy. As pathomechanisms and genotype-phenotype correlations are not completely understood, we aimed to provide further insights into the phenotypic and genetic spectrum. We here present a multicenter case series of ten unrelated individuals from four European countries using systematic MRI re-evaluation, protein structure analysis, and prediction score modeling. In two cases, pregnancy was terminated due to brain malformations. Amongst the eight living individuals, the phenotypic range showed various severity. Global developmental delay and severe motor impairment with tetraparesis was present in 63% and 50% of the subjects, respectively. Epilepsy was observed in 75% of the cases, which showed infantile onset in 83% and a refractory course in 50%. One individual presented a novel TUBA1A-associated electroclinical phenotype with evolvement from early myoclonic encephalopathy to continuous spike-and-wave during sleep. Neuroradiological features comprised a heterogeneous spectrum of cortical and extracortical malformations including rare findings such as cobblestone lissencephaly and subcortical band heterotopia. Two individuals developed hydrocephalus with subsequent posterior infarction. We report four novel and five previously published TUBA1A missense variants whose resulting amino acid substitutions likely affect longitudinal, lateral, and motor protein interactions as well as GTP binding. Assessment of pathogenic and benign variant distributions in synopsis with prediction scores revealed sections of variant enrichment and intolerance to missense variation. We here extend the clinical, neuroradiological, and genetic spectrum of TUBA1A tubulinopathy and provide insights into residue-specific pathomechanisms and genotype-phenotype correlations.

Disorders of Neuronal Migration/Organization Convey the Highest Risk of Neonatal Onset Epilepsy Compared With Other Congenital Brain Malformations

BACKGROUND

Although seizures in neonates are common and often due to acute brain injury, 10-15% are unprovoked from congenital brain malformations. A better understanding of the risk of neonatal-onset epilepsy by the type of brain malformation is essential for counseling and monitoring.

METHODS

In this retrospective cohort study, we evaluated 132 neonates with congenital brain malformations and their risk of neonatal-onset epilepsy. Malformations were classified into one of five categories based on imaging patterns on prenatal or postnatal imaging. Infants were monitored with continuous video EEG (cEEG) for encephalopathy and paroxysmal events in addition to abnormal neuroimaging.

RESULTS

Seventy-four of 132 (56%) neonates underwent EEG monitoring, and 18 of 132 (14%) were diagnosed with neonatal-onset epilepsy. The highest prevalence of epilepsy was in neonates with disorders of neuronal migration/organization (9/34, 26%; 95% confidence interval [CI] = 13-44%), followed by disorders of early prosencephalic development (6/38, 16%; 95% CI = 6-31%), complex total brain malformations (2/16, 13%; 95% CI = 2-38%), and disorders of midbrain/hindbrain malformations (1/30, 3%; 95% CI = 0-17%). Of neonates with epilepsy, 5 of 18 (28%) had only electrographic seizures, 13 of 18 (72%) required treatment with two or more antiseizure medicines (ASMs), and 7 of 18 (39%) died within the neonatal period.

CONCLUSION

Our results demonstrate that disorders of neuronal migration/organization represent the highest-risk group for early-onset epilepsy. Seizures are frequently electrographic only, require treatment with multiple ASMs, and portend a high mortality rate. These results support American Clinical Neurophysiology Society recommendations for EEG monitoring during the neonatal period for infants with congenital brain malformations.

Inherited Developmental and Epileptic Encephalopathies

Epileptic encephalopathies often have a genetic etiology. The epileptic activity itself exerts a direct detrimental effect on neurodevelopment, which may add to the cognitive impairment induced by the underlying mutation (“developmental and epileptic encephalopathy”). The focus of this review is on inherited syndromes. The phenotypes of genetic disorders affecting ion channels, metabolic signalling, membrane trafficking and exocytosis, cell adhesion, cell growth and proliferation are discussed. Red flags suggesting family of genes or even specific genes are highlighted. The knowledge of the phenotypical spectrum can indeed prompt the clinician to suspect specific etiologies, expediting the diagnosis.

Lissencephaly: Update on diagnostics and clinical management

Lissencephaly represents a spectrum of rare malformations of cortical development including agyria, pachygyria and subcortical band heterotopia. The progress in molecular genetics has led to identification of 31 lissencephaly-associated genes with the overall diagnostic yield over 80%. In this review, we focus on clinical and molecular diagnosis of lissencephaly and summarize the current knowledge on histopathological changes and their correlation with the MRI imaging. Additionally we provide the overview of clinical follow-up recommendations and available data on epilepsy management in patients with lissencephaly.

Clinical and neuroimaging findings in patients with lissencephaly/subcortical band heterotopia spectrum: a magnetic resonance conventional and diffusion tensor study

PURPOSE

To clarify brain abnormalities on magnetic resonance imaging (MRI) and its clinical implications in lissencephaly/subcortical band heterotopia (LIS/SBH) spectrum patients.

METHODS

The clinical severity and classification according to Di Donato were retrospectively reviewed in 23 LIS/SBH spectrum patients. The morphological and signal abnormalities of the brainstem, corpus callosum, and basal ganglia were also assessed. The brainstem distribution pattern of the corticospinal tract (CST) was analyzed by diffusion tensor imaging (DTI) and categorized into two types: normal pattern, in which the CST and medial lemniscus (ML) are separated by the dorsal portion of the transverse pontine fiber, and the abnormal pattern, in which the CST and ML are juxtaposed on the dorsal portion of a single transverse pontine fiber. Correlations between MR grading score and potential additional malformative findings of the brain and clinical symptoms were investigated.

RESULTS

All patients with grade 3 (n = 5) showed brainstem deformities, signal abnormalities of pontine surface and had a tendency of basal ganglia deformity and callosal hypoplasia whereas those abnormalities were rarely seen in patients with grade 1 and 2 (n = 18). For DTI analysis, the patients with grade 3 LIS/SBH had typically abnormal CST, whereas the patients with grade 1 and 2 LIS/SBH had normal CST. The classification was well correlated with CST and brainstem abnormalities and clinical severity.

CONCLUSION

MR assessment including DTI analysis may be useful in assessing the clinical severity in LIS/BH spectrum and may provide insight into its developmental pathology.

Pathophysiological Significance of WDR62 and JNK Signaling in Human Diseases

The c-Jun N-terminal kinase (JNK) is highly evolutionarily conserved and plays important roles in a broad range of physiological and pathological processes. The WD40-repeat protein 62 (WDR62) is a scaffold protein that recruits different components of the JNK signaling pathway to regulate several human diseases including neurological disorders, infertility, and tumorigenesis. Recent studies revealed that WDR62 regulates the process of neural stem cell mitosis and germ cell meiosis through JNK signaling. In this review we summarize the roles of WDR62 and JNK signaling in neuronal and non-neuronal contexts and discuss how JNK-dependent signaling regulates both processes. WDR62 is involved in various human disorders via JNK signaling regulation, and may represent a promising therapeutic strategy for the treatment of related diseases.