Maria Margherita Mancardi

Gain-of-function mutations in IFIH1 cause a spectrum of human disease phenotypes associated with upregulated type I interferon signaling

The type I interferon system is integral to human antiviral immunity. However, inappropriate stimulation or defective negative regulation of this system can lead to inflammatory disease. We sought to determine the molecular basis of genetically uncharacterized cases of the type I interferonopathy Aicardi-Goutières syndrome and of other undefined neurological and immunological phenotypes also demonstrating an upregulated type I interferon response. We found that heterozygous mutations in the cytosolic double-stranded RNA receptor gene IFIH1 (also called MDA5) cause a spectrum of neuroimmunological features consistently associated with an enhanced interferon state. Cellular and biochemical assays indicate that these mutations confer gain of function such that mutant IFIH1 binds RNA more avidly, leading to increased baseline and ligand-induced interferon signaling. Our results demonstrate that aberrant sensing of nucleic acids can cause immune upregulation.

An open-label trial of levetiracetam in severe myoclonic epilepsy of infancy

Objective: To conduct an open-label, add-on trial on safety and efficacy of levetiracetam in severe myoclonic epilepsy of infancy (SMEI). Patients and Methods: SMEI patients were recruited from different centers according to the following criteria: age ≥3 years; at least four tonic-clonic seizures/month during the last 8 weeks; previous use of at least two drugs. Levetiracetam was orally administrated at starting dose of approximately 10 mg/kg/day up to 50 to 60 mg/kg/day in two doses. Treatment period included a 5- to 6-week up-titration phase and a 12-week evaluation phase. Efficacy variables were responder rate by seizure type and reduction of the mean number per week of each seizure type. Analysis was performed using Fisher exact and Wilcoxon tests. Results: Twenty-eight patients (mean age: 9.4 ± 5.6 years) entered the study. Sixteen (57.1%) showed SCN1A mutations. Mean number of concomitant drugs was 2.5. Mean levetiracetam dose achieved was 2,016 mg/day. Twenty-three (82.1%) completed the trial. Responders were 64.2% for tonic-clonic, 60% for myoclonic, 60% for focal, and 44.4% for absence seizures. Number per week of tonic-clonic (median: 3 vs 1; p = 0.0001), myoclonic (median: 21 vs 3; p = 0.002), and focal seizures (median: 7.5 vs 3; p = 0.031) was significantly decreased compared to baseline. Levetiracetam effect was not related to age at onset and duration of epilepsy, genetic status, and concomitant therapy. Levetiracetam was well tolerated by subjects who completed the study. To date, follow-up ranges 6 to 36 months (mean, 16.2 ± 13.4). Conclusion: Levetiracetam add-on is effective and well tolerated in severe myoclonic epilepsy of infancy. Placebo-controlled studies should confirm these findings.

Brain MRI findings in severe myoclonic epilepsy in infancy and genotype-phenotype correlations.

Summary:  Introduction: To determine the occurrence of neuroradiological abnormalities and to perform genotype–phenotype correlations in severe myoclonic epilepsy of infancy (SMEI, Dravet syndrome).

Familial Occurrence of Febrile Seizures and Epilepsy in Severe Myoclonic Epilepsy of Infancy (SMEI) Patients with SCN1A Mutations

Summary:  Purpose: The role of the familial background in severe myoclonic epilepsy of infancy (SMEI) has been traditionally emphasized in literature, with 25–70% of the patients having a family history of febrile seizures (FS) or epilepsy. We explored the genetic background of SMEI patients carrying SCN1A mutations to further shed light on the genetics of this disorder.

Severe Epilepsy in X-Linked Creatine Transporter Defect (CRTR-D)

Disorders of creatine synthesis or its transporter resulting in neurological impairment with mental retardation and epilepsy have only been recognized in recent years. To date, the epileptic disorder observed in creatine transporter deficiency (CRTR‐D) has been described as a mild phenotype with infrequent seizures and favorable response to common antiepileptic drugs.

Paediatric anti-N-methyl-d-aspartate receptor encephalitis: The first Italian multicenter case series

BACKGROUND Given the rarity of this condition, especially in children, there is a paucity of large reported paediatric case series of anti-N-methyl-d-aspartate receptor encephalitis. METHODS To contribute to define the features of this condition, we describe retrospectively a new nationwide case series of 20 children (50% females), referred by 13 Italian centres. RESULTS Mean age at onset was 8 years (range 3-17). Prodromal symptoms were reported in 31.6%; onset was with neurological symptoms in 70%, and with behavioural/psychiatric disturbances in 30%. Most patients developed a severe clinical picture (90%), and 41% experienced medical complications; children 12-18 years old seemed to be more severe and symptomatic than younger patients. All children received first-line immune therapy; second-line treatment was administered to 45%. Relapses occurred in 15%. At last follow-up (mean 23.9 months, range 5-82), 85% patients had mRS 0-1; this rate was higher among older patients, and in those receiving first immune therapy within 1 month. CONCLUSIONS Our case series confirms a symptomatologic core of paediatric anti-N-methyl-d-aspartate receptor encephalitis, even though displaying some distinctive features that may be explained by a specific genetic background or by the limited number of patients. The growing incidence of this condition, the relative age-dependent variability of its manifestations, the availability of immunotherapy and the possible better outcome with early treatment impose a high index of clinical suspicion be maintained. In the absence of data suggesting other specific etiologies, paediatricians should consider this diagnosis for children presenting with neurological and/or behavioural or psychiatric disturbances, regardless of age and gender.

TBC1D24 genotype–phenotype correlation: Epilepsies and other neurologic features

Objective: To evaluate the phenotypic spectrum associated with mutations in TBC1D24. Methods: We acquired new clinical, EEG, and neuroimaging data of 11 previously unreported and 37 published patients. TBC1D24 mutations, identified through various sequencing methods, can be found online (http://lovd.nl/TBC1D24). Results: Forty-eight patients were included (28 men, 20 women, average age 21 years) from 30 independent families. Eighteen patients (38%) had myoclonic epilepsies. The other patients carried diagnoses of focal (25%), multifocal (2%), generalized (4%), and unclassified epilepsy (6%), and early-onset epileptic encephalopathy (25%). Most patients had drug-resistant epilepsy. We detail EEG, neuroimaging, developmental, and cognitive features, treatment responsiveness, and physical examination. In silico evaluation revealed 7 different highly conserved motifs, with the most common pathogenic mutation located in the first. Neuronal outgrowth assays showed that some TBC1D24 mutations, associated with the most severe TBC1D24-associated disorders, are not necessarily the most disruptive to this gene function. Conclusions: TBC1D24-related epilepsy syndromes show marked phenotypic pleiotropy, with multisystem involvement and severity spectrum ranging from isolated deafness (not studied here), benign myoclonic epilepsy restricted to childhood with complete seizure control and normal intellect, to early-onset epileptic encephalopathy with severe developmental delay and early death. There is no distinct correlation with mutation type or location yet, but patterns are emerging. Given the phenotypic breadth observed, TBC1D24 mutation screening is indicated in a wide variety of epilepsies. A TBC1D24 consortium was formed to develop further research on this gene and its associated phenotypes.

Type 1 diabetes and epilepsy: more than a casual association?

To the Editors: In 2006, McCorry et al. reported a strong epidemiologic association between type 1 diabetes mellitus (T1DM) and idiopathic generalized epilepsy (IGE) and claimed that this link would support an autoimmune pathogenesis for IGE (McCorry et al., 2006). However, O’Connel and coworkers did not confirm an increased risk of epilepsy among a series of patients with T1DM (O’Connell et al., 2008). We reviewed 249 T1DM patients (145 male; mean age 16.3 € 7.02 years, range 1.7–34.5 years; mean age at disease onset 7.7 € 6.9 years; range 0.8–18 years) attending the Diabetes Clinic at G. Gaslini Institute, Genoa, where a collaborative network provides epidemiologic data by an active surveillance model (Cotellessa et al., 2003). Extensive research was undertaken through the electronic database and subjects not followed up during the previous year were excluded. Epilepsy was diagnosed when ‡2 unprovoked euglycemic seizures (blood glucose >3.9 and <11.1 mmol/L) and syndromic classification (Commission on Classification and Terminology of the ILAE, 1989) was confirmed by reviewing clinical (family history, seizures type onset and frequency, response to treatment) and instrumental [electroencephalography (EEG), neuroimaging] data. Among 249 T1DM patients, 6 showed the electroclinical features of idiopathic epilepsy (4 IGE, 2 focal idiopathic epilepsy) (Table 1). In this group, mean age of T1DM onset was 4.6 € 2.7 years; mean age at first seizure was 6.7 € 4.4 years. None of these patients had a family history of epilepsy in firstand second-degree relatives. In all patients but one (case 4), T1DM preceded epilepsy onset, with a mean of 2.8 years (range 0.7–6.9 years). Patient 1 had concomitant celiac disease. Dosage of glutamic-acid decarboxylase antibodies (GADA) was available in two patients at T1DM diagnosis and in all cases at the last follow-up (Table 1). The high proportion of IGE observed in our series (4 of 249, 1.6%) (Hauser & Banerjee, 2008) confirms the data reported by McCorry et al. (McCorry et al., 2006). In all patients but one, T1DM manifested years before epilepsy. This may simply reflect different age of onset of the two conditions. Alternatively, it could support an autoimmune mechanism starting with T1DM and then affecting the central nervous system (McCorry et al., 2006). We did not perform GADA evaluation methodically at epilepsy onset in our patients, so that no definitive conclusion can be drawn about the existence of a pathogenetic link between GADA and epilepsy in T1DM patients (Striano et al., 2008). Interestingly, the patient with partial response to antiepileptic therapy (case 4) is the only one with recent GADA positivity. Because of the retrospective analysis, epilepsy could be underrecognized or overestimated in our T1DM population, but this is unlikely to explain the higher than expected degree of the association. Because both epilepsy and T1DM are serious worldwide problems with high medical and social management costs, this possible association deserves further investigation by prospective studies involving multiple centers.

Anti-glutamic acid decarboxylase limbic encephalitis without epilepsy evolving into dementia with cerebellar ataxia.

OBJECTIVES To expand the spectrum of the clinical presentation of anti-glutamic acid decarboxylase antibodies-related limbic encephalitis and to improve the recognition of this entity. DESIGN Case study. SETTING University hospital. PATIENT An 11-year-old-girl with progressive mood and behavioral disorder, speech impairment, and short-term memory impairment who manifested cerebellar ataxia with nystagmus during the disease course. INTERVENTIONS Blood and cerebrospinal fluid analysis including autoantibodies, electroencephalography, brain and spinal magnetic resonance imaging, and cognitive and neuropsychological assessment were performed. High-dose methylprednisolone sodium succinate pulses, cycles of intravenous immunoglobulins, mycophenolate mofetil, and rituximab as well as antipsychotics and benzodiazepine were administered. RESULTS Diagnosis of anti-glutamic acid decarboxylase antibodies-related limbic encephalitis was made. The clinical features during the first months of disease included only mood, behavioral, and memory impairment. After 5 months, despite immunotherapies, cerebellar ataxia with nystagmus appeared with brain magnetic resonance imaging evidence of cerebral atrophy. No clinical or infraclinical seizures were recorded during follow-up. CONCLUSIONS Anti-glutamic acid decarboxylase antibodies-related limbic encephalitis can present with only behavioral or neuropsychological symptoms without any epileptic disorder. Moreover, cerebellar ataxia related to anti-glutamic acid decarboxylase antibodies can be observed in patients with limbic encephalitis during the disease course.

Anti-NMDAR encephalitis misdiagnosed as Hashimoto's encephalopathy

Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is a well-defined autoimmune disorder. Hashimotos encephalopathy (HE) is a still controversial entity, lacking definite diagnostic criteria. We described a 14-year-old-girl presenting with a clinical picture consistent with the diagnosis of anti-NMDAR encephalitis, confirmed by NMDAR antibody testing. Four years earlier, she had presented a similar episode of acute encephalopathy diagnosed as HE. Anti-NMDAR encephalitis and HE share similar clinical features so that the differential diagnosis can be difficult if specific antibodies are not tested. The correct diagnosis of anti-NMDAR encephalitis is crucial to plan the appropriate management and follow-up, namely in term of oncological screening, since it can be paraneoplastic in origin. We suggest to re-evaluate the clinical history of all subjects with previous HE diagnosis in order to evaluate the possible diagnosis of anti-NMDAR encephalitis and plan the appropriate management of these patients.