Progressive skeletal myopathy,a phenotypic variant of desmin myopathy associated with desmin mutations

Desmin myopathy is a familial or sporadic disorder characterized by the presence of desmin mutations that cause skeletal muscle weakness associated with cardiac conduction block, arrhythmia and heart failure. Distinctive histopathologic features include intracytoplasmic accumulation of desmin-reactive deposits and electron-dense granular aggregates in skeletal and cardiac muscle cells. We describe two families with features of adult-onset slowly progressive skeletal myopathy without cardiomyopathy. N342D point mutation was present in the desmin helical rod domain in patients of family 1, and I451M mutation was found in the non-helical tail domain in patients of family 2. Of interest, the same I451M mutation has previously been reported in patients with cardiomyopathy and no signs of skeletal myopathy. Some carriers of the I451M mutation did not develop any disease, suggesting incomplete penetrance. Expression studies demonstrated inability of the N342D mutant desmin to form cellular filamentous network, confirming the pathogenic role of this mutation, but the network was not affected by the tail-domain I451M mutation. Progressive skeletal myopathy is a rare phenotypic variant of desmin myopathy allelic to the more frequent cardio-skeletal form.     

De novo POLR2A p.(Ile457Thr) variant associated with early-onset encephalopathy and cerebellar atrophy: expanding the phenotypic spectrum

BackgroundHeterozygous POLR2A variants have been recently reported in patients with a neurodevelopmental syndrome characterized by profound infantile-onset hypotonia. POLR2A encodes the highly conserved RBP1 protein, an essential subunit of the DNA-dependent RNA polymerase II.Case presentationWe investigated a 12-year-old girl presenting with an early-onset encephalopathy characterized by psychomotor delay, facial dysmorphism, refractory epilepsy with variable seizure types, behavioural abnormalities, and sleep disorder. Brain MRI showed a slowly progressive cerebellar atrophy. Trio-exome sequencing (Trio-ES) revealed the de novo germline variant NM_000937.5:c.1370T>C; p.(Ile457Thr) in POLR2A. This variant was previously reported in a subject with profound generalized hypotonia and muscular atrophy by Haijes et al. Our patient displayed instead a severe epileptic phenotype with refractory hypotonic seizures with impaired consciousness, myoclonic jerks, and drop attacks.ConclusionThis case expands the clinical spectrum of POLR2A-related syndrome, highlighting its phenotypic variability and supporting the relevance of epilepsy as a core feature of this emerging condition.     

Cortical interneuron dysfunction in epilepsy associated with autism spectrum disorders

Autism and epilepsy are two associated disorders that are highly prevalent, share common developmental origins, and demonstrate substantial heritability. In this review, cross‐disciplinary data in a rapidly evolving field that bridges neurology and psychiatry are synthesized to identify shared biologic mechanisms. The relationship between these debilitating, lifelong conditions is examined at the clinical, genetic, and neurophysiologic levels in humans and in animal models. Scopus and PubMed searches were used to identify relevant literature. Clinical observations have prompted speculation about the interdependence of autism and epilepsy, but causal relationships have proved difficult to determine. Despite their heritability, the genetic basis of autism spectrum disorder (ASD) and epilepsy has remained largely elusive until the advent of next‐generation sequencing. This approach has revealed that mutations that are either causal or confer an increased disease risk are found in numerous different genes, any one of which accounts for only a small percentage of cases. Conversely, even cases with identical clinical phenotypes can be genetically heterogeneous. Candidate gene identification has facilitated the development of mouse genetic models, which in parallel with human studies have implicated shared brain regions and circuits that mediate disease expression. Diverse genetic causes of ASD and epilepsy converge on cortical interneuron circuits as one important mediator of both disorders. Cortical interneurons are among the most diverse cell types in the brain and their unique chemical and electrical coupling exert a powerful inhibitory influence on excitatory neurons via the release of the neurotransmitter, γ‐aminobutyric acid (GABA). These multifaceted approaches have validated theories derived from the field of developmental neurobiology, which propose that the neurologic and neuropsychiatric manifestations are caused by an altered ratio of excitation to inhibition in the cortex.     

The phenotypic spectrum of ARX mutations

Mutations in the ARX gene can result in many different phenotypes, including phenotypes associated with severe brain malformations and less severe phenotypes associated with syndromic or non-syndromic forms of XLMR. There seems to be a consistent genotype-phenotype correlation and both interfamilial and intrafamilial variability of expression of some of the mutations, particularly the common 428-451dup(24 bp) mutation. Familiarity with the phenotypic spectrum of ARX mutations is helpful in determining when to request ARX mutation analysis.     

Metabolic and mitochondrial disorders associated with epilepsy in children with autism spectrum disorder

Autism spectrum disorder (ASD) affects a significant number of individuals in the United States, with the prevalence continuing to grow. A significant proportion of individuals with ASD have comorbid medical conditions such as epilepsy. In fact, treatment-resistant epilepsy appears to have a higher prevalence in children with ASD than in children without ASD, suggesting that current antiepileptic treatments may be suboptimal in controlling seizures in many individuals with ASD. Many individuals with ASD also appear to have underlying metabolic conditions. Metabolic conditions such as mitochondrial disease and dysfunction and abnormalities in cerebral folate metabolism may affect a substantial number of children with ASD, while other metabolic conditions that have been associated with ASD such as disorders of creatine, cholesterol, pyridoxine, biotin, carnitine, γ-aminobutyric acid, purine, pyrimidine, and amino acid metabolism and urea cycle disorders have also been associated with ASD without the prevalence clearly known. Interestingly, all of these metabolic conditions have been associated with epilepsy in children with ASD. The identification and treatment of these disorders could improve the underlying metabolic derangements and potentially improve behavior and seizure frequency and/or severity in these individuals. This paper provides an overview of these metabolic disorders in the context of ASD and discusses their characteristics, diagnostic testing, and treatment with concentration on mitochondrial disorders. To this end, this paper aims to help optimize the diagnosis and treatment of children with ASD and epilepsy.This article is part of a Special Issue entitled “Autism and Epilepsy”.     

SCN2A基因突变所致癫痫的遗传和表型特点

目的 探讨SCN2A(Sodium channel,voltage-gated,type II,alpha)基因突变所致癫痫的遗传及表型特点。方法 收集广东三九脑科医院癫痫中心2016年8至2021年4月收治的癫痫患儿,应用全外显捕获高通量测序技术发现SCN2A基因突变者,回顾性总结分析患儿临床及遗传资料。结果 共收集14例SCN2A基因突变阳性患儿,其中男7例,女7例,起病年龄1 d～6岁,其中3月龄内起病者8例(57.1%),3月龄后起病者6例(42.9%)。共发现13种突变,均为杂合错义突变。2例携带相同母源SCN2A突变,均为良性家族性癫痫; 3例携带父源突变,其中2例发作缓解(66.7%); 9例为新发突变,4例发作缓解(44.4%)。14例SCN2A突变癫痫患儿存在多种发作类型,以局灶性发作(64.3%)、痉挛发作(42.9%)、强直发作(35.7%)为主,其他发作类型较为少见; 8例患者有丛集性发作(57.1%)。14例患儿脑电图可见多种放电模式,以局灶性放电8例(57.1%)、弥漫性放电6例(42.9%)、多灶性放电5例(35.7%)多见。头部磁共振成像(Magnetic resonance imaging,MRI)以大脑发育不良(白质发育不良、白质变性、脑室发育不良、胼胝体发育不良、弥漫性脑萎缩)多见(42.9%)。除2例良性家族性癫痫患儿外,12例发育性/癫痫性脑病患儿,2例大田原综合征,3例韦斯特综合征,3例发育性脑病,3例发育性癫痫性脑病,1例婴儿游走性部分性发作,发育均呈中重度发育迟缓; 其中3月龄前起病者(早发SCN2A相关癫痫)10例,5例发作缓解; 3月龄后起病者(晚发SCN2A相关癫痫)2例,1例发作缓解。14例患儿抗癫痫治疗方案有较大个体差异,2例良性家族性癫痫对德巴金效果佳; 12例发育性/癫痫性脑病患儿中10例早发SCN2A相关癫痫患儿有6例尝试奥卡西平,4例有效(66.7%); 3例晚发患儿,1例应用且无效,但无加重发作。结论 SCN2A基因突变以错义突变为主,新发错义突变较遗传性突变预后差。SCN2A突变导致电压门控钠离子通道(Voltage-gated Na channel,VGNC或Na_v)的Ⅱ型Na_v1.2两种功能改变:获得功能和丧失功能,早发型(起病年龄<3月龄)Na_v1.2以获得功能为主,对钠离子通道阻滞剂(Sodium channel blockers,SCBs)效果佳; 晚发型(起病年龄≥3月龄)Na_v1.2以丧失功能为主,对SCBs效果差,甚至可能加重发作。SCBs首选适量苯妥英钠治疗。其他治疗如奥卡西平、生酮饮食、促肾上腺皮质激素(Adrenocorticotropic horme,ACTH)、氨己烯酸亦可尝试,且应个体化调整治疗方案。     

Refractory photosensitive epilepsy associated with a complex rearrangement of chromosome 2

We describe the relevant clinical and therapeutic parameters in a single patient with a complex chromosome 2 abnormality presenting with refractory myoclonic photosensitive epilepsy. FISH technology using yeast artificial chromosomes (YACs) was employed to determine breakage points, microdeletions and inversions on the affected chromosome. In this patient with refractory photosensitive epilepsy, 12 breakpoints and one small inversion were identified on the abnormal chromosome 2. Our data can be used in further genetic studies on the exact location and identification of photosensitivity genes.     

Clinical and neurophysiologic spectrum associated with atypical absence seizures in children with intractable epilepsy

The aim of this study was to describe the clinical and neurophysiologic correlates of atypical absence seizures in children with intractable epilepsy. In a retrospective review, 19 children with videoelectroencephalographic monitoring (female n=14; male n=5) fulfilled the electroclinical criteria for this seizure type. Atypical absence seizures occurred in a spectrum of clinical conditions associated with educational disability and intractable seizures. In comparison with children with only atypical absence seizures, children with atypical absence in association with multiple seizure types were more likely to have severe educational disability (n=11 of 13; P = .01), a slower ictal frequency (n=10 of 13; P = .01), and slow background rhythms for age (n = 13 of 13; P = .03). This study illustrates the broad clinical spectrum in which atypical absence seizures are encountered. Differentiation between children with only atypical absence seizures and children with multiple seizure types can be useful with respect to potential academic ability.     

Neutral lipid storage disease with myopathy: Further phenotypic characterization of a rare PNPLA2 variant

Neutral lipid storage disease with myopathy is a rare disorder of lipid metabolism caused by variants in the Patatin-Like Phospholipase Domain Containing 2 (PNPLA2) gene. Diagnosis is often delayed due to variable presentations, which is of concern due to increased risk of cardiomyopathy. Better phenotype–genotype characterization is necessary to improve speed and accuracy of diagnosis. Here, we describe a 32-year-old woman of Hmong descent with progressive muscle pain and weakness who had a muscle biopsy with characteristic features of a lipid storage myopathy. Genetic testing revealed a homozygous splice site variant in PNPLA2, c.757 + 1G > T. This case, in combination with the one previously reported case of this PNPLA2 variant, also in a family of Hmong descent, suggests this particular variant may be unique to the Hmong population, a Southeast Asian minority group living in the United States, who immigrated to the United States as refugees after the Vietnam War.     

Chromatic sensitive epilepsy: a variant of photosensitive epilepsy.

We herein report 4 Japanese children who suffered epileptic seizures while watching a popular animated TV program. They showed a photoparoxysmal response that is more frequently observed in response to rapid color (blue/red) frame changes than monochromatic ones. These patients were all considered to have photosensitive epilepsy; however, chromatic sensitivity also plays an important role in the generation of such seizures.     

Familial focal epilepsy with variable foci mapped to chromosome 22q12: Expansion of the phenotypic spectrum

We aimed to refine the phenotypic spectrum and map the causative gene in two families with familial focal epilepsy with variable foci (FFEVF). A new five-generation Australian FFEVF family (A) underwent electroclinical phenotyping, and the original four-generation Australian FFEVF family (B) (Ann Neurol, 44, 1998, 890) was re-analyzed, including new affected individuals. Mapping studies examined segregation at the chromosome 22q12 FFEVF region. In family B, the original whole genome microsatellite data was reviewed. Five subjects in family A and 10 in family B had FFEVF with predominantly awake attacks and active EEG studies with a different phenotypic picture from other families. In family B, reanalysis excluded the tentative 2q locus reported. Both families mapped to chromosome 22q12. Our results confirm chromosome 22q12 as the solitary locus for FFEVF. Both families show a subtly different phenotype to other published families extending the clinical spectrum of FFEVF.     

The -1021C->T DBH gene variant is not associated with epilepsy or antiepileptic drug response

Dopamine beta-hydroxylase (DBH) catalyzes the conversion of dopamine to norepinephrine (NE). Animal studies show that genes in the NE pathway are candidates for susceptibility to epilepsy and antiepileptic drug (AED) response. The authors genotyped the -1021C-->T major functional polymorphism in the DBH gene in 675 patients with epilepsy and 1,087 controls. The authors found no association with epilepsy, several epilepsy subtypes, or AED response. The results suggest that the -1021C-->T variant does not contribute to epilepsy.     

The phenotypic spectrum of dystonia in Mohr-Tranebjaerg syndrome

Mohr-Tranebjaerg syndrome (MTS) is an X-linked recessive disorder characterized by deafness and dystonia. However the phenotypic expression of dystonia has not been systematically defined. We report clinical, neurophysiological, and ophthalmological data on 6 subjects from 3 Australian kindreds, including 2 with novel mutations, together with a systematic review of the literature, in order to define the phenotypic expression of dystonia. Profound hearing impairment in affected males develops by infancy and precedes the development of dystonia, which varies in time of onset from the first to the sixth decades, with a peak in the second and third decades. Dystonia in MTS tends to be focal, segmental, or multifocal in distribution at onset, with a predilection for the upper body, variably involving the head, neck, and upper limbs. The majority of patients have progression or generalization of their dystonia regardless of age of onset. Within our 3 kindreds, we observed relative intrafamilial homogeneity but interfamilial variation. The median time to the development of moderate-severely disabling dystonia in these subjects was 11 years. Associated features included progressive cognitive decline, pyramidal signs, and in 1 patient, gait freezing and postural instability. Optic atrophy and cortical visual impairment were both observed. We report for the first time a female patient who developed multiple disabling neurological complications of MTS. Our findings more clearly define and expand the phenotype of both the dystonia and other neurological features of MTS and have implications for the diagnosis and management of this condition.     

Molybdenum cofactor deficiency – phenotypic variability in a family with a late-onset variant

In a family with molybdenum cofactor deficiency, the onset in the index case was delayed until 1 year of age, when the patient presented with an episode of lethargy and inconsolable crying culminating in a seizure. By 17 months she showed mild motor delay, regression in language skills, and feeding difficulties. Progressive global deterioration followed, associated with sustained irritability, dystonic posturing, and further seizures, before her condition subsequently plateaued. Low plasma uric acid, raised urinary xanthine and hypoxanthine, and positive urinary sulphite were found, which, coupled with assay of sulphite oxidase activity in cultured fibroblasts, confirmed the diagnosis. A sibling had isolated lens dislocation and an identical biochemical profile. MRI in both children was strikingly abnormal. Molybdenum cofactor deficiency may present as a late-onset variant with considerable phenotypic variability.     

Inclusion of hemimegalencephaly into the phenotypic spectrum of NPRL3 pathogenic variants in familial focal epilepsy with variable foci

Despite tremendous progress through next generation sequencing technologies, familial focal epilepsies are insufficiently understood. We sought to identify the genetic basis in multiplex Palestinian families with familial focal epilepsy with variable foci (FFEVF). Family I with 10 affected individuals and Family II with five affected individuals underwent detailed phenotyping over three generations. The phenotypic spectrum of the two families varied from nonlesional focal epilepsy including nocturnal frontal lobe epilepsy to severe structural epilepsy due to hemimegalencephaly. Whole‐exome sequencing and single nucleotide polymorphism array analysis revealed pathogenic variants in NPRL3 in each family, a partial ~38‐kb deletion encompassing eight exons (exons 8‐15) and the 3′‐untranslated region of the NPRL3 gene in Family I, and a de novo nonsense variant c.1063C>T, p.Gln355* in Family II. Furthermore, we identified a truncating variant in the PDCD10 gene in addition to the NPRL3 variant in a patient with focal epilepsy from Family I. The individual also had developmental delay and multiple cerebral cavernomas, possibly demonstrating a digenic contribution to the individual's phenotype. Our results implicate the association of NPRL3 with hemimegalencephaly, expanding the phenotypic spectrum of NPRL3 in FFEVF and underlining that partial deletions are part of the genotypic spectrum of NPRL3 variants.     

Dementia associated with epilepsy

In this review, we explore the relationship between epilepsy and cognition and between epilepsy and dementia. Chronic epilepsy, particularly mesial temporal lobe epilepsy (MTLE) with hippocampal sclerosis, may be associated with impaired cognition, which can be secondary to uncontrolled seizures, to adverse effects of antiepileptic drugs (AEDs) or to the underlying biological abnormality. The choice of an adequate AED with an appropriate dose regimen may lead to a favorable outcome. This feature is especially relevant in elderly patients with dementia and associated epilepsy, a vulnerable population in which the diagnosis of seizures can be difficult and for whom treatment guidelines are not yet available. Based on available information and on data derived from studies with other populations, recommendations for the management of these patients are presented.