Autism in siblings with autosomal dominant nocturnal frontal lobe epilepsy

In 1999, Hirose et al. reported a Japanese family with autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE) associated with a neuronal nicotinic acetylcholine receptor α4 subunit mutation (S252L). We followed the siblings of this family, and found that the elder brother had Asperger’s disorder without mental retardation (MR) and the younger brother had autistic disorder with profound MR. The clinical epileptic features of the siblings were very similar, and both had deficits in socialization, but their cognitive development differed markedly. It thus seems that epilepsy is the direct phenotype of the S252L mutation, whereas other various factors modulate the cognitive and social development. No patients with ADNFLE have previously been reported to have autism spectrum disorder or profound MR.     

Tobacco habits modulate autosomal dominant nocturnal frontal lobe epilepsy

Mutations in neuronal nicotinic acetylcholine receptors have been demonstrated in autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE). The beneficial effect of nicotine administration was previously reported in one single case. We investigated the influence of the tobacco habits of 22 subjects from two pedigrees with alpha4 mutations (776ins3 and S248F). Subjects were interviewed with respect to pattern of nicotine intake and seizures. Seizure freedom was significantly associated with tobacco use (P=0.024). All seven nonsmokers with manifest ADNFLE had persistent seizures. Seizure fluctuations, including long remissions, corresponded to changes in tobacco habits in several patients. One patient who recently had begun treatment with transdermal nicotine experienced improvement. We conclude that tobacco appears to be an environmental factor that influences seizure susceptibility in ADNFLE. Inactivation by desensitization of the mutant receptors by nicotine may explain the beneficial effect. The efficacy and safety of transdermal nicotine in ADNFLE should be further explored.     

Autosomal dominant nocturnal frontal lobe epilepsy

Abstract. Autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE) is an idiopathic epilepsy, with a spectrum of clinical manifestations, ranging from brief, stereotyped, sudden arousals to more complex dystonic–dyskinetic seizures. Video–polysomnography allows a correct differential diagnosis. There is no difference between sporadic nocturnal frontal lobe epilepsy (NFLE) and ADNFLE in the clinical and neurophysiological findings. ADNFLE is the first idiopathic epilepsy for which a genetic basis has been identified. Mutations have been found in two genes (CHRNA4 and CHRNB2) coding for neuronal nicotinic receptor subunits (4 and 2, respectively). Contrasting data have been reported on the effect of these mutations on the functionality of the receptor.Moreover, the incomplete data on the neuronal network/s in which this receptor is involved, make difficult the understanding of the genotype–phenotype correlation. This is an overview on the clinical and genetic aspects of ADNFLE including a discussion of some open questions on the role of the neuronal nicotinic receptor subunit mutations in the pathogenesis of this form of epilepsy.     

常染色体显性遗传夜间额叶癫痫

常染色体显性遗传性夜间额叶癫痫（autosomal dominant nocturnal frontal epilepsy，ADNFLE）是一种常染色体显性遗传的特发性局灶性癫痫综合征，1994年首先由Scheffer等描述，夜间成串的运动症状发作为最显著的临床特征。1995年Steinlein等首先发现其致病基因，是第一个被发现由基因变异引起的特发性癫痫综合征。本文对其临床特点、遗传学及发病机制的研究进展加以综述。     

Phenotypic comparison of two Scottish families with mutations in different genes causing autosomal dominant nocturnal frontal lobe epilepsy

PURPOSE: Mutations in genes coding for the alpha 4 and beta 2 subunits of the neuronal nicotinic acetylcholine receptor receptor (CHRN) are known to cause autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE). Here we examined the phenotypes in two families, from the same ethnic and geographic backgrounds, with ADNFLE as a result of mutations in these two different subunits of CHRN. METHODS: All affected family members underwent a detailed clinical evaluation and review of available EEG, neuroimaging, and videotapes of seizures. The molecular study of family D is reported here; family S has a previously reported mutation in the beta 2 subunit of CHRN. RESULTS: A total of 16 individuals with ADNFLE were identified in the two families. In both families, seizure semiology, age at seizure onset, and the natural history of the seizure disorder was similar. Intrafamilial variation in terms of severity of epilepsy syndrome was present in both families. A significant number of individuals from each family had a history of psychological problems. The molecular study of family D revealed a Ser248Phe mutation in the alpha 4 subunit of CHRN. CONCLUSIONS: The epilepsy phenotype is not distinguishable in the two families who have ADNFLE as a result of mutations in genes coding for different CHRN subunits. This is likely to be due to the similar functional consequences of each mutation on the CHRN receptor.     

A Korean kindred with autosomal dominant nocturnal frontal lobe epilepsy and mental retardation

BACKGROUND: A Korean family had distinctive clinical and neuroimaging features and carried the same genetic mutation that was found in a previously described Japanese kindred with autosomal dominant nocturnal frontal lobe epilepsy. OBJECTIVE: To describe the first Korean family with autosomal dominant nocturnal frontal lobe epilepsy. METHODS: Members of a large family, including 9 affected individuals from 3 generations, underwent a comprehensive genetic, clinical, electroencephalographic, neuropsychological, and neuroimaging evaluation. Affected members were tested for possible mutations in transmembrane regions 1 through 3 of the neuronal nicotinic acetylcholine receptor alpha4 subunit (CHRNA4) by direct sequencing and subsequent restriction analysis. RESULTS: Seizures began in childhood, presenting as nocturnal episodes of staring, confusion, shouting, perioral movements, unintelligible speech, and hand waving. Some patients had ictal or interictal epileptiform activity in the temporal and/or frontocentral areas. Neurological examination and brain magnetic resonance imaging results showed no abnormalities, except that all patients available for testing had mild to moderate mental retardation. Fluorodeoxyglucose F 18 with positron emission tomography showed mild decreased glucose uptake in the superior and middle frontal regions, more so on the left than on the right. Patient response to carbamazepine was poor. All affected members were heterozygous for the CHRNA4 Ser252Leu mutation. CONCLUSIONS: Disorders associated with mutations in the transmembrane region 2 of CHRNA4 are genetically and phenotypically heterogeneous. Distinctive features of this kindred include (1) mental retardation in all affected members available for testing, (2) abnormal brain findings on fluorodeoxyglucose F 18 with positron emission tomography, (3) poor response to carbamazepine, and (4) full penetrance.     

Evidence for a fourth locus for autosomal dominant nocturnal frontal lobe epilepsy

Mutations responsible for autosomal dominant nocturnal frontal lobe epilepsy have been identified in two members of the neuronal nicotinic acetylcholine receptor gene family: CHRNA4(ENFL1 locus) and CHRNB2 (ENFL3 locus) coding for alpha4 and beta2 subunit, respectively. However, mutations in these genes account for only a minority (less than 10%) of cases. For a third ADNFLE locus (ENFL2) on chromosome 15q24 the gene was not identified. The involvement of the three loci in the pathogenesis of ADNFLE was investigated in 12 unrelated Italian families, selected on the basis of anamnestic and video-polysomnographic data. Compliant family members were typed for polymorphic markers spanning the analyzed chromosome regions. Linkage analyses excluded association of all chromosome regions with ADNFLE in 72% of cases. In two, four and one families it was impossible to ascertain or exclude association with ENFL1, ENFL2, or ENFL3, respectively, however, no mutations have been detected in the nicotinic receptor genes located in these regions. These data strongly suggest that ENFL1, ENFL2 and ENFL3 are minor loci for the disease and point to the existence of at least a fourth locus for ADNFLE.     

Electroclinical picture of autosomal dominant nocturnal frontal lobe epilepsy in a Japanese family

PURPOSE: Autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE) is the first described partial epilepsy syndrome known to be due to a single gene mutation. We found a first Japanese ADNFLE family with a novel mutation of the neuronal nicotinic acetylcholine receptor (nAChR) alpha4 subunit (CHRNA4) gene. The aim of this report is precisely to describe the electroclinical manifestations of ADNFLE in this family and to compare these findings with those of other families reported previously in the literature. METHODS: Three affected family members were investigated electroclinically by close clinical observation, interictal EEG, video-EEG monitoring, magnetic resonance imaging, and single-photon-emission tomography. Information about other affected family members was obtained from either the spouse or the parents. Mutations within the CHRNA4 gene were examined in seven family members. RESULTS: The clinical manifestations and diagnostic findings in the members of this family were consistent with ADNFLE. However, there were intrafamilial and interfamilial variations in clinical features. The seizures of the patients were brief tonic seizures, with hyperventilation in children and secondarily generalized tonic-clonic convulsions in adults. The onset of the children's seizures began in infancy and early childhood. The children's seizures were sometimes provoked by movement and sound stimulation, and did not respond to antiepileptic drugs. On the other hand, the adults' seizures disappeared spontaneously or were easily controlled with carbamazepine. Three children showed hyperactivity, and two children had mild mental retardation. All patients had impaired consciousness during their seizures and no auras. A novel missense mutation (c755C>T) in exon 5 of the CHRNA4 gene was found in four affected family members. CONCLUSIONS: The electroclinical pictures of a Japanese family with ADNFLE were basically the same as those of other families reported, but with slight differences. ADNFLE is probably not uncommon, and it is very likely that there are unidentified patients with this inherited disorder in Japan.     

夜发性额叶癫痫三家系临床和遗传学特征

目的 分析夜发性额叶癫痫3个家系的临床、脑电图和遗传学特征.方法 在3个夜发性额叶癫痫家系患者及部分亲属中收集临床、脑电图及神经影像学等资料,并采用测序方法筛查烟碱型乙酰胆碱受体(nAChR)α4、β2和α2亚单位编码基因(CHRNA4、CHRNB2和CHRNA2).结果 3个家系中有6例患者(其中男5例),平均年龄(20.5±11.5)岁,平均发病年龄(7.3±5.5)岁,临床表现为夜发性额叶发作,具体发作类型包括姿势性发作2例,躯体自动症发作4例,最多每夜发作6次.发作间期、发作期视频脑电图2例患者表现为正常或动作伪差,2例表现为前部导联慢波节律,3例出现前部导联棘波、棘慢波及尖波.神经系统及神经影像检查未见异常.抗癫痫药物治疗反应良好.CHRNA4、CHRNB2和CHRNA2部分序列(包含跨膜区1～3)筛查未见突变.结论 夜发性额叶癫痫是一种遗传异质性癫痫综合征.     

Severe autosomal dominant nocturnal frontal lobe epilepsy associated with psychiatric disorders and intellectual disability

Autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE) is a relatively benign epilepsy syndrome with few comorbidities. Here we describe two families with unusually severe ADNFLE, with associated psychiatric, behavioral, and cognitive features. Detailed clinical data on 17 affected individuals were obtained, and genotyping of microsatellite markers, linkage analysis, and sequencing of candidate genes was performed. The severe ADNFLE phenotype in these families was often refractory to treatment, with status epilepticus occurring in 24% of subjects. Psychiatric or behavioral disorders occurred in 53%, with intellectual disability in 24%, and developmental regression in two individuals. No mutations were identified in alpha4, alpha2, or beta2 nAChR subunits. In one family there was evidence of linkage to a region of 15q24 without nAChR subunit genes. In conclusion, severe ADNFLE has significant medical, psychiatric, and intellectual morbidity. The molecular basis of severe ADNFLE is unknown but may involve non-nAChR-related mechanisms.     

The macrostructure and microstructure of sleep in patients with autosomal dominant nocturnal frontal lobe epilepsy.

The electroclinical features of autosomal dominant nocturnal frontal lobe epilepsy have been recently described. Although some patients reported a poor quality of sleep, daytime tiredness, and sleepiness, their sleep macrostructure appeared to be indistinguishable from those of the control group. The aim of this study was to evaluate the macro- and microstructure of sleep in a sample of autosomal dominant nocturnal frontal lobe epilepsy patients, diagnosed by videopolysomnography. The authors selected 16 patients, 8 with daytime complaints (morning tiredness and/or excessive sleepiness) (group 1) and 8 without those complaints (group 2). The classical macrostructure of sleep and the microstructure, according to the cyclic alternating pattern (CAP) scoring rules, were compared with another group of 8 healthy controls. In group 1 the motor attacks during sleep took place more frequently during CAP and were significantly related to phase A of the CAP cycle in comparison to group 2 (P = 0.04). Group 2 had a sleep microstructure similar to the controls, whereas group 1 showed higher CAP/nonrapid eye movement sleep (CAP rate) and a higher number of CAP cycles with respect to controls (P = 0.012 and P = 0.001) and to group 2 (P = 0.05 and P = 0.04). The analysis of sleep microstructure showed an increase in sleep instability in patients with autosomal dominant nocturnal frontal lobe epilepsy and daytime sleep complaints and indicated the relationship between sleep fragmentation, nocturnal motor seizures, and daytime symptoms.     

A novel mutation of CHRNA4 responsible for autosomal dominant nocturnal frontal lobe epilepsy

OBJECTIVE: To identify the mutation responsible for autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE) in a nonwhite family. BACKGROUND: ADNFLE is newly recognized as an entity of idiopathic partial epilepsy. Recently, two different mutations of the neuronal nicotinic acetylcholine receptor alpha4 subunit (CHRNA4) gene were identified in a white family as a cause of ADNFLE. METHODS: Four affected and three unaffected individuals in three generations of a Japanese family with ADNFLE, and 100 unrelated healthy Japanese volunteers were studied. Clinical features and EEG findings in affected individuals were consistent with those of ADNFLE reported in white families with ADNFLE. Mutations within the CHRNA4 gene were screened for using single-strand conformation polymorphism analysis (SSCA) and were determined by direct sequencing. The mutation identified was sought in volunteers by the amplification refractory mutation system. RESULTS: A C-to-T exchange (C755T) was found in exon 5 of the CHRNA4 gene on one allele of affected individuals. C755T segregated in affected individuals and was not found in 200 alleles obtained from the volunteers. C755T replaced serine 252 (Ser252) in the second membrane-spanning domain (M2) of CHRNA4 with a leucine. Ser252 is conserved characteristically in the alpha-subunit of acetylcholine receptor and is considered to play an important role in channel function. CONCLUSION: C755T is a novel missense mutation of the CHRNA4 gene causing autosomal dominant nocturnal frontal lobe epilepsy in this Japanese family.     

Further evidence of genetic heterogeneity in autosomal dominant distal motor neuronopathy

Distal hereditary motor neuronopathy is a genetically and clinically heterogeneous disorder. To date, five loci, and their relative genes, have been mapped on chromosomes 7p14, 7q11, 9q34, 11q12 and 12q24, respectively. We describe an Italian family with autosomal dominant distal HMN starting at around 30 years of age with weakness and atrophy of distal leg muscles and pyramidal features. We performed genetic linkage analysis on chromosomes 7p14, 9q34, 11q12 and 12q24. Moreover we sequenced the genes mapped to 7q11 and 12q24. Negative LOD scores excluded linkage to 7p14, 9q34, and 11q12 chromosomes in our family. No mutations were found in genes mapped to 7q11 and 12q24. In addition, because of pyramidal features, we performed the linkage analysis to all the known loci for autosomal dominant hereditary spastic paraparesis. The analysis was negative thus excluding a complicated form of autosomal dominant hereditary spastic paraparesis. These data further confirm a genetic heterogeneity within inherited motor neuronopathy.     

A new locus for autosomal dominant nocturnal frontal lobe epilepsy maps to chromosome 1

BACKGROUND: Autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE) is caused by mutations in the alpha4 subunit of the neuronal nicotinic acetylcholine receptor (CHRNA4) gene, mapping on chromosome 20q13.2. A second ADNFLE locus was mapped on chromosome 15q24. OBJECTIVE: To report a new third ADNFLE locus on chromosome 1 in a large Italian family. METHODS: The authors performed a clinical and genetic study in a large, three-generation ADNFLE family from southern Italy, including eight affected individuals and three obligate carriers. RESULTS: The age at onset of seizures was around 9 years of age and all affected individuals manifested nocturnal partial seizures of frontal lobe origin. Interictal awake and sleep EEG recordings showed no definite epileptiform abnormalities in most patients. Ictal video-EEG showed that the attacks were partial seizures with a frontal lobe semiology. Intellectual and neurologic examinations, and brain CT or MRI results were always normal. Carbamazepine was effective in all treated patients. Exclusion mapping of the known loci linked to ADNFLE-ENFL1, and ENFL2, on chromosomes 20q13.2 and 15q24-was performed on the pedigree before starting the genome-wide linkage analysis. The whole genome scan mapping allowed the identification of a new ADNFLE locus spanning the pericentromeric region of chromosome 1. CONCLUSIONS: The authors provided evidence for a third locus associated to autosomal dominant nocturnal frontal lobe epilepsy on chromosome 1. Among the known genes mapping within this critical region, the ss2 subunit of the nicotinic receptor (CHRNB2) represents the most obvious candidate.     

Neuropsychological function in patients with a single gene mutation associated with autosomal dominant nocturnal frontal lobe epilepsy

Autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE) is a nonlesional condition associated with mutation of the gene coding for the α4 nicotinic acetylcholine receptor (nAChR). The nAChR modulates aspects of memory and attention. We examined the neuropsychological phenotype of ADNFLE, with a particular emphasis on understanding the impact on frontal lobe functions. We used standard clinical tests as well as focused measures of frontal lobe function in a well-defined group of patients with ADNFLE. Their performance was compared with that of a group of age-, sex-, and education-matched control participants. Patients with ADNFLE showed impairments on tasks requiring cognitive flexibility against a background of well-preserved intellectual abilities. In accord with existing research, verbal memory impairments were identified in the patient group; the level of impairment on these tasks correlated with disease-related factors. In our study of ADNFLE associated with one mutation, cognitive flexibility appears to be the core cognitive deficit.