Autosomal dominant acute necrotizing encephalopathy maps to 2q12.1-2q13

Genetic and environmental risk factors of acute infection-triggered encephalopathy

Acute encephalopathy is a constellation of syndromes in which immune response, metabolism and neuronal excitation are affected in a variable fashion. Most of the syndromes are complex disorders, caused or aggravated by multiple, genetic and environmental risk factors. Environmental factors include pathogenic microorganisms of the antecedent infection such as influenza virus, human herpesvirus-6 and enterohemorrhagic Escherichia coli, and drugs such as non-steroidal anti-inflammatory drugs, valproate and theophylline. Genetic factors include mutations such as rare variants of the SCN1A and RANBP2 genes, and polymorphisms such as thermolabile CPT2 variants and HLA genotypes. By altering immune response, metabolism or neuronal excitation, these factors complicate the pathologic process. On the other hand, some of them could provide promising targets to prevent or treat acute encephalopathy.

RANBP2 mutation in an Indian child with recurrent acute necrotizing encephalopathy

BACKGROUND

Acute necrotizing encephalopathy (ANE) is a rare disorder characterized by encephalopathy following a febrile illness, mostly viral. Most cases are sporadic; however, recurrent and familial cases have been linked to RANBP2 mutation.

DESCRIPTION OF THE CASE

This is a description of a three and half years old girl with recurrent ANE with RANBP2 mutation (c.1754 C>T (p.T585M)). She had two episodes of encephalopathy, each following a short non-specific febrile illness. Neuroradiologically, she had typical findings involving bilateral thalami during the first episode and involving bilateral temporal and occipital lobes, bilateral cerebellar hemispheres and brainstem during the second episode. She was managed with intravenous gamma globulin and dexamethasone during both the episodes. She recovered significantly with residual deficits in her cognitive and language domains.

CONCLUSIONS

In relevant clinic-radiological scenarios both isolated and recurrent ANE should be considered because of treatment and long-term outcome related implications.

Acute necrotizing encephalopathy: an underrecognized clinicoradiologic disorder

Acute necrotizing encephalopathy (ANE) is a rare but distinctive type of acute encephalopathy with global distribution. Occurrence of ANE is usually preceded by a virus-associated febrile illness and ensued by rapid deterioration. However, the causal relationship between viral infections and ANE and the exact pathogenesis of ANE remain unclear; both environmental and host factors might be involved. Most cases of ANE are sporadic and nonrecurrent, namely, isolated or sporadic ANE; however, few cases are recurrent and with familial episodes. The recurrent and familial forms of ANE were found to be incompletely autosomal-dominant. Further the missense mutations in the gene encoding the nuclear pore protein Ran Binding Protein 2 (RANBP2) were identified. Although the clinical course and the prognosis of ANE are diverse, the hallmark of neuroradiologic manifestation of ANE is multifocal symmetric brain lesions which are demonstrated by computed tomography (CT) or magnetic resonance imaging (MRI). The treatment of ANE is still under investigation. We summarize the up-to-date knowledge on ANE, with emphasis on prompt diagnosis and better treatment of this rare but fatal disease.

Clinical outcome of acute necrotizing encephalopathy in related to involving the brain stem of single institution in Korea

Purpose

Acute necrotizing encephalopathy (ANE) is a fulminant disease of the brain characterized by bilateral thalamic lesions, and is prevalent among children in East Asia. The prognosis of ANE is usually poor with a high mortality rate and neurological sequelae. This study aimed to delineate the clinical characteristics and prognostic factors of ANE.

Methods

We retrospectively analyzed clinical data of 399 pediatric patients with encephalitis who were admitted to Samsung Medical Center from December 1998 to March 2011. We enrolled ten patients (11 cases) with ANE and analyzed their demographic, clinical, and neuroimaging data. The location and extent of the brain regions were checked based on fluid-attenuated inversion recovery, T1-, and T2-weighted imaging findings; the presence of contrast enhancement, restricted diffusion, and hemorrhage.

Results

Ten patients were identified, including one patient with two episodes. The median age of onset was 1.5 years (0.4-8.4 years). The mortality rate was 40%, and only 30% of patients survived without neurological sequelae. The definite involvement of the brainstem on brain magnetic resonance imaging was significantly correlated with mortality (P=0.04).

Conclusion

Broad and extensive brainstem involvement suggested the fulminant course of ANE. Early diagnosis of ANE before brainstem involvement, through careful identification of symptoms of brain dysfunction, may be the best way to achieve better neurological outcomes.

Acute necrotizing encephalopathy (ANE1): rare autosomal-dominant disorder presenting as acute transverse myelitis

The term "acute transverse myelitis (ATM)" comprises various non-traumatic disorders that eventually can be associated with a focal myelopathy. Patients characteristically present with an acutely occurring paraparesis/plegia and require a comprehensive and timely diagnostic work up for the initiation of an appropriate treatment. We present a case of a 36-year-old female patient with a rare genetic disorder (ANE1: Acute Necrotizing Encephalopathy due to a RANBP2 mutation) who presented with an acute quadriplegia. Following an acute pulmonal infection, she rapidly (< 24 h) developed a severe quadriplegia (total motor score 38) with some facial sensory symptoms (perioral hypoesthesia). Magnetic resonance imaging (MRI) revealed a combination of longitudinal extensive transverse myelitis and symmetrical thalamic lesions. A work-up for infectious and systemic diseases was negative; specifically, no findings related to multiple sclerosis, neuromyelitis optica or vascular disorders. After empirical high dose steroid treatment and rehabilitation therapy, the patient gained almost normal gait and upper limb function. She was found to carry an autosomal-dominant missense mutation in the RANBP2 gene predisposing for ANE. Gene segregation was confirmed in other family members that had been affected by other episodes of acute steroid-responsive encephalopathies. We propose that a redefined diagnostic workup of ATM might include ANE1, as the frequency of this rare disorder might be underestimated.

Acute disseminated encephalomyelitis

Acute disseminated encephalomyelitis is an immune-mediated inflammatory and demyelinating disorder of the central nervous system, commonly preceded by an infection. It principally involves the white matter tracts of the cerebral hemispheres, brainstem, optic nerves, and spinal cord. Acute disseminated encephalomyelitis mainly affects children. Clinically, patients present with multifocal neurologic abnormalities reflecting the widespread involvement in central nervous system. Cerebrospinal fluid may be normal or may show a mild pleocytosis with or without elevated protein levels. Magnetic resonance image (MRI) shows multiple demyelinating lesions. The diagnosis of acute disseminated encephalomyelitis requires both multifocal involvement and encephalopathy by consensus criteria. Acute disseminated encephalomyelitis typically has a monophasic course with a favorable prognosis. Multiphasic forms have been reported, resulting in diagnostic difficulties in distinguishing these cases from multiple sclerosis. In addition, many inflammatory disorders may have a similar presentation with frequent occurrence of encephalopathy and should be considered in the differential diagnosis of acute disseminated encephalomyelitis.

Recurrent acute necrotizing encephalopathy in a Korean child: the first non-Caucasian case

Acute necrotizing encephalopathy is characterized by fever, seizures, acute encephalopathy, and rapid progression to coma. It is usually associated with viral illness and shows characteristic brain magnetic resonance imaging features, including symmetrical involvement of bilateral thalami, brain stem, white matter, and cerebellum. After the first report of recurrent or familial cases in 2003, similar cases were found exclusively in American and European regions. The association with Ran-binding protein 2 gene was identified in 75% of familial or recurrent cases. This report describes a previous healthy 22-month-old boy who recurrently manifested typical clinical and radiological characteristics of acute necrotizing encephalopathy. His neurological outcome worsened with repeated episodes. There was no family history of acute necrotizing encephalopathy and no mutation in the coding region of Ran-binding protein 2 (RANBP2) gene. This is the first reported case of recurrent acute necrotizing encephalopathy in a non-Caucasian family.

Immunomodulatory therapy in recurrent acute necrotizing encephalopathy ANE1: is it useful?

Acute Necrotizing Encephalopathy (ANE) is a rare disorder characterized by fever, seizures and rapid progression to coma after the onset of a viral infection. Most cases are sporadic, however the observation of multiple cases in the same family with recurrent episodes of ANE led to the identification of a genetic form of the disorder, called ANE1, and to the discover of the causative mutation in RANBP2 gene. We report the first Italian child with ANE1 carrying the common c.1880C>T mutation in the RANBP2 gene, who presented three episodes of acute encephalopathy in the first two years of life. The child showed a less severe clinical and neuroradiological course with respect to the previously reported patients. During the acute encephalopathy episodes he was treated with steroids and immunoglobulin. A very low steroid maintenance therapy was administered after the second episode until the onset of the third. Thirty days after the last episode he started monthly intravenous immunoglobulin that might be used for prevention of viral infections. At the moment he is still continuing a low steroid maintenance therapy and monthly IVIG. We could hypothesize that the less severe clinical presentation of the third episode might be correlated to the steroid treatment or that the patient grew older. Despite there is no evidence to support that ANE1 is an immune-mediated disease, immunomodulatory therapy might be considered in the management of ANE1 cases especially in early childhood, in which a fatal course has been frequently reported. Further studies will be necessary to define the clinical, immunological and genetic aspects, as well as the outcome of immunomodulatory therapy in patients with ANE1.

Novel human reovirus isolated from children with acute necrotizing encephalopathy

For many encephalitis cases, the cause remains unidentified. After 2 children (from the same family) received a diagnosis of acute necrotizing encephalopathy at Centre Hospitalier Universitaire (Tours, France), we attempted to identify the etiologic agent. Because clinical samples from the 2 patients were negative for all pathogens tested, urine and throat swab specimens were added to epithelial cells, and virus isolates detected were characterized by molecular analysis and electron microscopy. We identified a novel reovirus strain (serotype 2), MRV2Tou05, which seems to be closely related to porcine and human strains. A specific antibody response directed against this new reovirus strain was observed in convalescent-phase serum specimens from the patients, whereas no response was observed in 38 serum specimens from 38 healthy adults. This novel reovirus is a new etiologic agent of encephalitis.

Autosomal dominant acute necrotising encephalopathy: a case report with possible disease-expression modification by coincidental homocysteinuria

We report the case of a 5-year old girl with autosomal dominant acute necrotising encephalopathy (ADANE), who presented with encephalopathy, seizures and coma following a short febrile illness. MR imaging demonstrated characteristic symmetrical, T2 hyper-intense changes involving the external capsule, thalami, brainstem and cerebellum. Unique to this case was co-existing previously unrecognized homocysteinuria due to cystathionine-β-synthase (CBS) deficiency. We discuss metabolic hypotheses of the pathophysiology of ADANE and suggest that the concurrent homocysteinuria may have contributed to the severe phenotype seen in this child, who has been left with profound neurological deficits.

Acute necrotizing encephalopathy in 3 brothers

Acute necrotizing encephalopathy (ANE) is a devastating and rapidly progressive neurologic disorder that occurs in healthy children after common viral infections. Typically, ANE is sporadic and does not recur. However, familial (ANE1) and recurrent cases have been reported and were recently linked to mutations in RANBP2 (RAN-binding protein 2). We report here a multiply affected kindred with recurrent familial ANE. These affected male siblings (a set of twins and their older brother) all presented with prodromal fever and upper respiratory tract infection that progressed within 72 hours to seizures, coma, and ultimately death, a course that is typical of ANE. It should be noted that 1 brother was treated with early aggressive management, including corticosteroids, and he survived for an additional 5 years. This represents the second reported case of familial ANE in the United States and the only case of male siblings with consanguineous parents. We hope that early recognition and growing awareness can lead to more effective treatment and better outcomes in the future.

Recurrent acute necrotizing encephalopathy following influenza A in a genetically predisposed family

Acute necrotizing encephalopathy (ANE) typically affects young, healthy children who develop rapid-onset severe encephalopathy triggered by viral infections. This disease is more commonly reported in Japan but occurs worldwide, although it remains under-recognized in Western countries. An autosomal dominant form, ANE1, was recently identified. We report the details of a 9-year-old Caucasian female who experienced recurrent ANE episodes at the ages of 9 months and 9 years. Brain magnetic resonance imaging findings were characteristic of ANE during both episodes, although more extensive in the recent episode, which resulted in severe neurological sequelae; influenza A was identified on bronchoalveolar lavage during this episode. Interestingly, there was evidence of peripheral polyneuropathy during the recent episode, which has not previously been described in sporadic ANE. Both the patient and her mother, who had also had postviral polyneuritis in the past, harbour a mutation in Ran-binding protein 2 (RANBP2); this occurred de novo in the mother and confers genetic susceptibility to ANE. Our case suggests that recurrent disease and/or an expanded clinical phenotype raises the possibility of ANE1; positive family history, although supportive, is not necessary as the mutation can occur de novo. Increased awareness may lead to earlier recognition and better treatment options.

Transcriptional regulation of the human ST6GAL2 gene in cerebral cortex and neuronal cells

The second human beta-galactoside alpha-2,6-sialyltransferase (hST6Gal II) differs from hST6Gal I, the first member of ST6Gal family, in substrate specificity and tissue expression pattern. While ST6GAL1 gene is expressed in almost all human tissues, ST6GAL2 shows a restricted tissue-specific pattern of expression, mostly expressed in embryonic and adult brain. In order to understand the mechanisms involved in the transcriptional regulation of ST6GAL2, we first characterized the transcription start sites (TSS) in SH-SY5Y neuroblastoma cells. 5' RACE experiments revealed multiple TSS located on three first alternative 5' exons, termed EX, EY and EZ, which are unusually close on the genomic sequence and are all located more than 42 kbp upstream of the first common coding exon. Using Taqman duplex Q-PCR, we showed that the ST6GAL2 transcripts initiated by EX or EY are mainly expressed in both brain-related cell lines and human cerebral cortex, testifying for the use of a similar transcriptional regulation in vivo. Furthermore, we also showed for the first time hST6Gal II protein expression in the different lobes of the human cortex. Luciferase reporter assays allowed us to define two sequences upstream EX and EY with a high and moderate promoter activity, respectively. Bioinformatics analysis and site-directed mutagenesis showed that NF-kappaB and NRSF are likely to act as transcriptional repressors, whereas neuronal-related development factors Sox5, Puralpha and Olf1, are likely to act as transcriptional activators of ST6GAL2. This suggests that ST6GAL2 transcription could be potentially activated for specific neuronal functions.

Acute disseminated encephalomyelitis with bilateral thalamic necrosis

Acute disseminated encephalomyelitis is a monophasic inflammatory demyelinating disease of the central nervous system involving the white matter, and to a lesser extent, the gray matter. Bilateral thalamic lesions have been reported in 12% of pediatric patients with acute disseminated encephalomyelitis. In most cases, there is a benign clinical course and complete resolution of the lesions. Here, we describe a case in which acute disseminated encephalomyelitis is associated with severe neurological deficits and bilateral thalamic necrosis. Necrosis should be considered in cases of acute disseminated encephalomyelitis with persistent severe neurological deficits. Its presence is a poor prognostic indicator.

Infection-triggered familial or recurrent cases of acute necrotizing encephalopathy caused by mutations in a component of the nuclear pore, RANBP2

Acute necrotizing encephalopathy (ANE) is a rapidly progressive encephalopathy that can occur in otherwise healthy children after common viral infections such as influenza and parainfluenza. Most ANE is sporadic and nonrecurrent (isolated ANE). However, we identified a 7 Mb interval containing a susceptibility locus (ANE1) in a family segregating recurrent ANE as an incompletely penetrant, autosomal-dominant trait. We now report that all affected individuals and obligate carriers in this family are heterozygous for a missense mutation (c.1880C-->T, p.Thr585Met) in the gene encoding the nuclear pore protein Ran Binding Protein 2 (RANBP2). To determine whether this mutation is the susceptibility allele, we screened controls and other patients with ANE who are unrelated to the index family. Patients from 9 of 15 additional kindreds with familial or recurrent ANE had the identical mutation. It arose de novo in two families and independently in several other families. Two other patients with familial ANE had different RANBP2 missense mutations that altered conserved residues. None of the three RANBP2 missense mutations were found in 19 patients with isolated ANE or in unaffected controls. We conclude that missense mutations in RANBP2 are susceptibility alleles for familial and recurrent cases of ANE.

Haploinsufficiency of RanBP2 is neuroprotective against light-elicited and age-dependent degeneration of photoreceptor neurons

Prolonged light exposure is a determinant factor in inducing neurodegeneration of photoreceptors by apoptosis. Yet, the molecular bases of the pathways and components triggering this cell death event are elusive. Here, we reveal a prominent age-dependent increase in the susceptibility of photoreceptor neurons to undergo apoptosis under light in a mouse model. This is accompanied by light-induced subcellular changes of photoreceptors, such as dilation of the disks at the tip of the outer segments, prominent vesiculation of nascent disks, and autophagy of mitochondria into large multilamellar bodies. Notably, haploinsufficiency of Ran-binding protein-2 (RanBP2) suppresses apoptosis and most facets of membrane dysgenesis observed with age upon light-elicited stress. RanBP2 haploinsufficiency promotes decreased levels of free fatty acids in the retina independent of light exposure and turns the mice refractory to weight gain on a high-fat diet, whereas light promotes an increase in hydrogen peroxide regardless of the genotype. These studies demonstrate the presence of age-dependent and RanBP2-mediated pathways modulating membrane biogenesis of the outer segments and light-elicited neurodegeneration of photoreceptors. Furthermore, the findings support a mechanism whereby the RanBP2-dependent production of free fatty acids, metabolites thereof or the modulation of a cofactor dependent on any of these, promote apoptosis of photoreceptors in concert with the light-stimulated production of reactive oxygen species.

Influenza-associated central nervous system dysfunction: a literature review

CONTEXT

Influenza is a viral pathogen that imposes an under-recognized burden of central nervous system (CNS) disease.

OBJECTIVE

To describe the epidemiology, clinical features and etiology of the CNS disease entities associated with influenza.

DATA SOURCES

English-language publications from MEDLINE.

DATA EXTRACTION

Articles were identified using "influenza, human"[Mesh] AND "nervous system diseases"[Mesh] and screened for inclusion based on relevance and scientific rigor.

RESULTS

Febrile seizure is the most frequently encountered influenza-associated CNS complication, with one in five children hospitalized with influenza experiencing one or more events. In most instances, symptoms resolve without neurological sequelae, although the risk for subsequent afebrile seizure may be increased. Influenza-associated encephalitis/encephalopathy is a less common but potentially more serious complication that is widely reported in Japanese populations, although cases from other East Asian countries, North America, and Europe have been described. Clinical manifestations are diverse, and typically involve febrile seizures and abnormal behaviors in mild cases, with rapid evolution through decreased consciousness to coma in severe forms. In cases of serious disease, the prognosis is often poor, with outcomes including death or severe neurological sequelae. Influenza is also a known trigger for a number of rarely encountered, yet often serious, CNS diseases, including the encephalopathic condition of Reye's syndrome, the peripheral neuropathy known as Guillain-Barré syndrome, and the lesser known complaints of Kleine-Levin syndrome and post-encephalitic Parkinson's disease.

CONCLUSIONS

Influenza imposes a sizeable burden of CNS disease. Increased awareness and monitoring of CNS function is indicated, especially in infants and young children.

[Acute necrotizing encephalopathy: patient with a relapsing and lethal evolution]

Acute necrotizing encephalopathy was initially reported in Japanese children. The rapid evolution and symmetrical brain lesions seen in the brainstem, cerebellum and specially in the thalamus characterize the disease. We studied a 7-month-old-girl, who presented with two episodes of rapid loss of consciousness and paresis without metabolic disturbances. At the first time she had a rapid improvement, but at the second episode the course was fulminant and in two days she lapsed into a clinical state of brain death. The magnetic resonance studies showed symmetrical lesions in the thalamus and additional lesions involving the brainstem and the cerebellum.

An approach to MRI of metabolic disorders in children

Inborn errors of metabolism are a difficult group of disorders for the neuroradiologist, as there are few good clinical or neuroradiological criteria for differentiating them. In this review, a technique of diagnosis by pattern recognition, supplemented by metabolic data from proton MR spectroscopy and microstructural data, as assessed by diffusion weighted images, is presented. Proper use of these neuroimaging tools can be very useful for separating these disorders into more manageable groups, and sometimes allows a specific diagnosis to be made.

Acute necrotizing encephalopathy of childhood in non-Asian patients: report of three cases and literature review

Acute necrotizing encephalopathy of childhood is a novel type of parainfectious encephalopathy with a racial and geographic predilection, rarely reported from other than East Asian areas. The objective was to describe the clinical, imaging, and other laboratory findings of non-Asian patients with acute necrotizing encephalopathy. Data were collected from three patients diagnosed in Athens over a 4-year period plus 16 cases reported from other European and North American countries. One of the Greek children died, and the other two had a normal outcome. A neuropathologic examination in the fatal case showed edematous necrosis without inflammatory, reactive, or proliferative changes. Data from Greek and other non-Asian patients support the homogeneity of the disease worldwide.

Acute necrotizing encephalopathy in caucasian children: two cases and review of the literature

Acute necrotizing encephalopathy is a fulminant neurologic disease seen predominantly in Japan and Taiwan. We present two cases diagnosed at a Canadian center within the same year in Caucasian children. Both were previously well, developed an acute viral illness with fever and vomiting, and progressed to brain death within 2 to 4 days. Neuroimaging and postmortem examination demonstrated the unique features of bilateral and severe necrosis of deep gray- and subcortical white-matter structures. The first case was associated with extensive, but transient, hepatic involvement, recent varicella and rotavirus infections, and detailed metabolic studies, including mitochondrial functional analysis, were normal. The second case tested positive for influenza A infection, whereas evidence of liver damage was lacking. Both children demonstrated early lymphopenia and myocardial necrosis, two features not previously associated with acute necrotizing encephalopathy. These cases are unique in their occurrence in non-Japanese children and are among the first published reports in Canada.

Progressive cavitating leukoencephalopathy: A novel childhood disease

We report 19 patients with a previously undelineated neurodegenerative syndrome characterized by episodic acute onset of irritability or neurological deficits between 2 months and 3.5 years of age, followed by steady or intermittent clinical deterioration. Seven children died between 11 months and 14 years of age. Cranial magnetic resonance imaging (MRI) shows patchy leukoencephalopathy with cavities, and vascular permeability, in actively affected regions. Early lesions affect corpus callosum and centrum semiovale, with or without cerebellar or cord involvement. After repeated episodes, areas of tissue loss coalesce with older lesions to become larger cystic regions in brain or spinal cord. Diffuse spasticity, dementia, vegetative state, or death ensues. Gray matter is spared until late in the course. In some, incomplete clinical or MRI recovery occurs after episodes. The clinical course varies from rapid deterioration to prolonged periods of stability that are unpredictable by clinical or MRI changes. Elevated levels of lactate in brain, blood, and cerebrospinal fluid, abnormal urine organic acids, and changes in muscle respiratory chain enzymes are present but inconsistent, without identifiable mitochondrial DNA mutations or deletions. Pathological studies show severe loss of myelin sparing U-fibers, axonal disruption, and cavitary lesions without inflammation. Familial occurrence and consanguinity suggest autosomal recessive inheritance of this distinct entity.