Microstructure of the cerebellum and its afferent pathways underpins dystonia in myoclonus dystonia.

BACKGROUND AND PURPOSE: Myoclonus dystonia due to a pathogenic variant in SGCE (MYC/DYT-SGCE) is a rare condition involving a motor phenotype associating myoclonus and dystonia. Dysfunction within the networks relying on the cortex, cerebellum, and basal ganglia was presumed to underpin the clinical manifestations. However, the microarchitectural abnormalities within these structures and related pathways are unknown. Here, we investigated the microarchitectural brain abnormalities related to the motor phenotype in MYC/DYT-SGCE. METHODS: We used neurite orientation dispersion and density imaging, a multicompartment tissue model of diffusion neuroimaging, to compare microarchitectural neurite organization in MYC/DYT-SGCE patients and healthy volunteers (HVs). Neurite density index (NDI), orientation dispersion index (ODI), and isotropic volume fraction (ISOVF) were derived and correlated with the severity of motor symptoms. Fractional anisotropy (FA) and mean diffusivity (MD) derived from the diffusion tensor approach were also analyzed. In addition, we studied the pathways that correlated with motor symptom severity using tractography analysis. RESULTS: Eighteen MYC/DYT-SGCE patients and 24 HVs were analyzed. MYC/DYT-SGCE patients showed an increase of ODI and a decrease of FA within their motor cerebellum. More severe dystonia was associated with lower ODI and NDI and higher FA within motor cerebellar cortex, as well as with lower NDI and higher ISOVF and MD within the corticopontocerebellar and spinocerebellar pathways. No association was found between myoclonus severity and diffusion parameters. CONCLUSIONS: In MYC/DYT-SGCE, we found microstructural reorganization of the motor cerebellum. Structural change in the cerebellar afferent pathways that relay inputs from the spinal cord and the cerebral cortex were specifically associated with the severity of dystonia.

Xq28 copy number gain causing moyamoya disease and a novel moyamoya syndrome.

BACKGROUND: The molecular anomalies causing moyamoya disease (MMD) and moyamoya syndromes (MMS) are unknown in most patients. OBJECTIVE: This study aimed to identify de novo candidate copy number variants (CNVs) in patients with moyamoya. METHODS: Rare de novo CNVs screening was performed in 13 moyamoya angiopathy trios using whole exome sequencing (WES) reads depth data and whole genome high density SNP array data. WES and SNP array data from an additional cohort of 115 unrelated moyamoya probands were used to search for recurrence of these rare de novo CNVs. RESULTS: Two de novo CNVs were identified in two unrelated probands by both methods and confirmed by qPCR. One of these CNVs, located on Xq28, was detected in two additional families. This interstitial Xq28 CNV gain is absent from curated gold standard database of control genomic variants and gnomAD databases. The critical region contains five genes, including MAMLD1, a major NOTCH coactivator. Typical MMD was observed in the two families with a duplication, whereas in the triplicated patients of the third family, a novel MMS associating moyamoya and various systemic venous anomalies was evidenced. CONCLUSION: The recurrence of this novel Xq28 CNV, its de novo occurrence in one patient and its familial segregation with the affected phenotype in two additional families strongly suggest that it is pathogenic. In addition to genetic counselling application, its association with pulmonary hypertension is of major importance for clinical care. These data also provide new insights into the genomic architecture of this emblematic, non-atherosclerotic, large vessel disease.

DNA repair functional analyses of NBN hypomorphic variants associated with NBN-related infertility.

Nijmegen breakage syndrome caused by biallelic pathogenic variants of the DNA-damage response gene NBN, is characterized by severe microcephaly, cancer proneness, infertility, and karyotype abnormalities. We previously reported NBN variants in siblings suffering from fertility defects. Here, we identify a new founder NBN variant (c.442A>G, p.(Thr148Ala)) in Lebanese patients associated with isolated infertility. Functional analyses explored preserved or altered functions correlated with their remarkably mild phenotype. Transcript and protein analyses supported the use of an alternative transcript with in-frame skipping of exons 4-5, leading to p84-NBN protein with a preserved forkhead-associated (FHA) domain. The level of NBN was dramatically reduced and the MRN complex delocalized to the cytoplasm. Interestingly, ataxia-elangiectasia mutated (ATM) also shifted from the nucleus to the cytoplasm, suggesting some interaction between ATM and the MRN complex at a steady state. The ATM pathway activation, attenuated in typical patients with NBS, appeared normal under camptothecin treatment in these new NBN-related infertile patients. Cell cycle checkpoint defect was present in these atypical patients, although to a lesser extent than in typical patients with NBS. In conclusion, we report three new NBN-related infertile patients and we suggest that preserved FHA domain could be responsible for the mild phenotype and intermediate DNA-damage response defects.

Visual sensory processing is altered in myoclonus dystonia.

BACKGROUND: Abnormal sensory processing, including temporal discrimination threshold, has been described in various dystonic syndromes. OBJECTIVE: To investigate visual sensory processing in DYT-SGCE and identify its structural correlates. METHODS: DYT-SGCE patients without DBS (DYT-SGCE-non-DBS) and with DBS (DYT-SGCE-DBS) were compared to healthy volunteers in three tasks: a temporal discrimination threshold, a movement orientation discrimination, and movement speed discrimination. Response times attributed to accumulation of sensory visual information were computationally modelized, with µ parameter indicating sensory mean growth rate. We also identified the structural correlates of behavioral performance for temporal discrimination threshold. RESULTS: Twenty-four DYT-SGCE-non-DBS, 13 DYT-SGCE-DBS, and 25 healthy volunteers were included in the study. In DYT-SGCE-DBS, the discrimination threshold was higher in the temporal discrimination threshold (P = 0.024), with no difference among the groups in other tasks. The sensory mean growth rate (µ) was lower in DYT-SGCE in all three tasks (P < 0.01), reflecting a slower rate of sensory accumulation for the visual information in these patients independent of DBS. Structural imaging analysis showed a thicker left primary visual cortex (P = 0.001) in DYT-SGCE-non-DBS compared to healthy volunteers, which also correlated with lower µ in temporal discrimination threshold (P = 0.029). In DYT-SGCE-non-DBS, myoclonus severity also correlated with a lower µ in the temporal discrimination threshold task (P = 0.048) and with thicker V1 on the left (P = 0.022). CONCLUSION: In DYT-SGCE, we showed an alteration of the visual sensory processing in the temporal discrimination threshold that correlated with myoclonus severity and structural changes in the primary visual cortex. © 2019 International Parkinson and Movement Disorder Society.

Expanding the Spectrum of Neurological Manifestations in Cutis Laxa, Autosomal Recessive, Type IIIA.

Cutis laxa is a heterogeneous group of diseases, characterized by abundant and wrinkled skin and a variable degree of intellectual disability. Cutis laxa, autosomal recessive, type IIIA and autosomal dominant 3 syndromes are caused by autosomal recessive or de novo pathogenic variants in ALDH18A1. Autosomal recessive variants are known to lead to the most severe neurological phenotype, and very few patients have been described.We describe a 13-month-old patient with cutis laxa, autosomal recessive, type IIIA, with an extremely severe phenotype, including novel neurological findings. This description enlarges the neurological spectrum associated to cutis laxa, autosomal recessive, type IIIA, and provides an additional description of this syndrome.

Early magnetic resonance imaging to detect presymptomatic leptomeningeal angioma in children with suspected Sturge-Weber syndrome.

AIM: We aimed to evaluate the contribution of early magnetic resonance imaging (MRI) for the presymptomatic diagnosis of Sturge-Weber syndrome (SWS) in infants with a facial port-wine birthmark (PWB). METHOD: Asymptomatic infants with a facial PWB who performed a first MRI scan before 3 months and a second MRI scan after 9 months were included in this study. Leptomeningeal enhancement on T1-weighted imaging and four indirect signs of leptomeningeal angioma (choroid plexus enlargement, cerebral atrophy, signal inversion of the white matter with T2 hyposignal, and T1 hypersignal) were screened on the first MRI scan and correlated with clinical and/or radiological diagnosis of SWS. RESULTS: Thirteen of 30 included patients had SWS with leptomeningeal angioma. Eleven had a leptomeningeal enhancement on the first MRI scan and 10 had associated indirect signs. The presence of a direct or at least one indirect sign of leptomeningeal angioma on the first MRI scan confirmed the diagnosis of SWS with a sensitivity of 100 per cent (95% confidence interval 75-100%) and a specificity of 94 per cent (71-100%). INTERPRETATION: Early diagnosis of SWS is possible on contrast-enhanced MRI performed in asymptomatic infants with a facial PWB before the age of 3 months. This early detection would help to select patients who may benefit from early neuroprotective intervention. WHAT THIS PAPER ADDS: Specific magnetic resonance imaging markers provide early diagnosis of leptomeningeal angioma in Sturge-Weber syndrome (SWS). Presymptomatic diagnosis of SWS should help to select patients for early therapy intervention.

Magnetic resonance imaging diagnosis of subependymal giant cell astrocytomas in follow-up of children with tuberous sclerosis complex: should we always use contrast enhancement?

BACKGROUND: Subependymal giant cell astrocytomas (SEGAs) arise in 10-26% of tuberous sclerosis complex (TSC) patients. SEGAs cause obstructive hydrocephalus and increase morbi-mortality. It is recommended that TSC patients be followed with contrast enhanced magnetic resonance imaging (CE-MRI), but repetitive use of gadolinium-based contrast-agents (GBCAs) may cause organ deposits. OBJECTIVE: To compare the diagnostic performances of non-CE- and CE-MRI to differentiate SEGAs from subependymal nodules in TSC patients during follow-up. MATERIALS AND METHODS: Thirty-five TSC patients (median age: 2.4 years) were enrolled in this retrospective single-center study from September 2007 to January 2019. Inclusion criteria were a certain diagnosis of TSC and at least three follow-up brain MRIs with GBCA injection. Two consecutive MRI scans per patient were selected and anonymized. Three radiologists performed a blinded review of non-enhanced and enhanced MRI sequences during different sessions. The diagnostic performances were compared (sensitivity, specificity, positive/negative predictive values, accuracy, inter/intra-observer agreements). RESULTS: The accuracies for detecting SEGAs were good and similar between the non-enhanced and enhanced MRI sequences. The sensitivity and specificity of non-CE-MRI to diagnose SEGA ranged from 75% to 100% and from 94% to 100%, respectively. The differences in numbers of false-positive and false-negative patients between non-CE- and CE-MRI never exceeded one case. Nodules size >10 mm, location near the Monro foramen, hydrocephalus and modifications between two consecutive MRI scans were significantly associated with the diagnosis of SEGA for the three readers (all P-values <0.05). Inter- and intra-observer agreements were also excellent for non-enhanced and enhanced MRI sequences (kappa=0.85-1 and 0.81-0.93, respectively). CONCLUSION: The performances of non-enhanced and enhanced MRI sequences are comparable for detecting SEGAs, questioning the need for systematic GBCA injections for TSC patients.

Three new cases of ataxia-telangiectasia-like disorder: No impairment of the ATM pathway, but S-phase checkpoint defect.

Ataxia-telangiectasia-like disorder (ATLD) is a rare genomic instability syndrome caused by biallelic variants of MRE11 (meiotic recombination 11) characterized by progressive cerebellar ataxia and typical karyotype abnormalities. These symptoms are common to those of ataxia-telangiectasia, which is consistent with the key role of MRE11 in ataxia-telangiectasia mutated (ATM) activation after DNA double-strand breaks. Three unrelated French patients were referred with ataxia. Only one had typical karyotype abnormalities. Unreported biallelic MRE11 variants were found in these three cases. Interestingly, one variant (c.424G>A) was present in two cases and haplotype analysis strongly suggested a French founder variant. Variants c.544G>A and c.314+4_314+7del lead to splice defects. The level of MRE11 in lymphoblastoid cell lines was consistently and dramatically reduced. Functional consequences were evaluated on activation of the ATM pathway via phosphorylation of ATM targets (KAP1 and CHK2), but no consistent defect was observed. However, an S-phase checkpoint activation defect after camptothecin was observed in these patients with ATLD. In conclusion, we report the first three French ATLD patients and a French founder variant, and propose an S-phase checkpoint activation study to evaluate the pathogenicity of MRE11 variants.

Clinical study of 19 patients with SCN8A-related epilepsy: Two modes of onset regarding EEG and seizures.

OBJECTIVE: To describe the mode of onset of SCN8A-related severe epilepsy in order to facilitate early recognition, and eventually early treatment with sodium channel blockers. METHODS: We reviewed the phenotype of patients carrying a mutation in the SCN8A gene, among a multicentric cohort of 638 patients prospectively followed by several pediatric neurologists. We focused on the way clinicians made the diagnosis of epileptic encephalopathy, the very first symptoms, electroencephalography (EEG) findings, and seizure types. We made genotypic/phenotypic correlation based on epilepsy-associated missense variant localization over the protein. RESULTS: We found 19 patients carrying a de novo mutation of SCN8A, representing 3% of our cohort, with 9 mutations being novel. Age at onset of epilepsy was 1 day to 16 months. We found two modes of onset: 12 patients had slowly emerging onset with rare and/or subtle seizures and normal interictal EEG (group 1). The first event was either acute generalized tonic-clonic seizure (GTCS; Group 1a, n = 6) or episodes of myoclonic jerks that were often mistaken for sleep-related movements or other movement disorders (Group 1b, n = 6). Seven patients had a sudden onset of frequent tonic seizures or epileptic spasms with abnormal interictal EEG leading to rapid diagnosis of epileptic encephalopathy. Sodium channel blockers were effective or nonaggravating in most cases. SIGNIFICANCE: SCN8A is the third most prevalent early onset epileptic encephalopathy gene and is associated with two modes of onset of epilepsy.

Recurrent KIF2A mutations are responsible for classic lissencephaly.

Kinesins play a critical role in the organization and dynamics of the microtubule cytoskeleton, making them central players in neuronal proliferation, neuronal migration, and postmigrational development. Recently, KIF2A mutations were identified in cortical malformation syndromes associated with microcephaly. Here, we detected two de novo p.Ser317Asn and p.His321Pro mutations in KIF2A in two patients with lissencephaly and microcephaly. In parallel, we re-evaluated the two previously reported cases showing de novo mutations of the same residues. The identification of mutations only in the residues Ser317 and His321 suggests these are hotspots for de novo mutations. Both mutations lead to a classic form of lissencephaly, with a posterior to anterior gradient, almost indistinguishable from LIS1-related lissencephaly. However, three fourths of patients also showed variable congenital and postnatal microcephaly, up to -5 SD. Located in the motor domain of the KIF2A protein, the Ser317 and His321 alterations are expected to disrupt binding or hydrolysis of ATP and consequently the MT depolymerizing activity. This report also establishes that KIF2A mutations represent significant causes of classic lissencephaly with microcephaly.

Epilepsy in young Tsc1(+/-) mice exhibits age-dependent expression that mimics that of human tuberous sclerosis complex.

OBJECTIVE: To describe the epileptic phenotype of Tsc1(+/-) mice pups in comparison with age-related seizures in human tuberous sclerosis complex (TSC). METHODS: Tsc1(+/-) and control mice underwent intracranial electroencephalography (EEG) recording at postnatal ages (P)8 to P33, with linear silicon probe implanted in the somatosensory cortex of one or both hemispheres for 8-24 h. Ictal events were classified visually by independent analyzers; distinct EEG patterns were related to age and analyzed to quantify field potential characteristics and signal dynamics between hemispheres. We collected retrospectively 20 infants with prenatally diagnosed TSC and EEG before seizure onset, and analyzed the electroclinical course of epilepsy, taking into account a first-line treatment by vigabatrin. RESULTS: Spontaneous seizures were disclosed in 55% of Tsc1(+/-) mice at P9-18. Three ictal patterns were identified: from P9 to P12 "spike clusters" consisted of recurring large spikes without clinical correlate; "spasm-like" discharges dominated from P13 to P16 consisting of high amplitude large field potential superimposed with or followed by fast activity repeated every 2-10 s for at least 20 s, accompanied by rhythmic limb contractions; from P14 to P18 a "tonic-clonic like" pattern comprised rhythmic spikes of increasing amplitude with tonic-clonic movements. Early onset "spike clusters" were mainly unilateral, whereas "spasm-like" and "tonic-clonic like" patterns were bilateral. Interhemispheric propagation was significantly faster for "tonic-clonic like" than for "spasm-like" events. In infants diagnosed prenatally with TSC, clusters of sharp waves or spikes preceded the first seizure, and vigabatrin prevented the development of seizures. Patients treated after seizure onset developed spasms or focal seizures that were pharmacoresistant in 66.7% of cases. SIGNIFICANCE: Tsc1(+/-) mice pups exhibit an age-dependent seizure pattern sequence mimicking early human TSC epilepsy features. Spike clusters before seizure onset in TSC should be considered as a first stage of epilepsy reinforcing the concept of preventive antiepileptic therapy.

EFFECTS: an expanded access program of everolimus for patients with subependymal giant cell astrocytoma associated with tuberous sclerosis complex.

BACKGROUND: Everolimus, a mammalian target of rapamycin (mTOR) inhibitor, has been shown to be effective and safe in the treatment of subependymal giant cell astrocytoma (SEGA) associated with tuberous sclerosis complex (TSC). The Everolimus For Fast Expanded aCcess in TSC SEGA (EFFECTS) study was designed to provide everolimus access to patients with SEGA associated with TSC and to mainly assess the safety and also efficacy of everolimus in a real-world setting. METHODS: EFFECTS was a phase 3b, open-label, noncomparative, multicenter, expanded access study. Eligible patients were ≥ 3 years of age, with a definite diagnosis of TSC, and with at least one SEGA lesion identified by MRI or CT scan. Patients received once daily everolimus (dose adjusted to attain a trough level of 5-15 ng/mL). Safety evaluation was the primary objective and included collection of adverse events (AEs) and serious AEs, with their severity and relationship to everolimus. Efficacy evaluation, which was the secondary objective, was based on the best overall response as per medical judgment. RESULTS: Of the 120 patients enrolled, 100 (83.3%) completed the study. Median age of patients was 11 years (range, 1-47). Median daily dose of everolimus was 5.82 mg (range, 2.0-11.8). Median duration of exposure was 56.5 weeks (range, 0.3-130). The overall incidence of AEs was 74.2%. Aphthous stomatitis (18 [15.0%]), pyrexia (18 [15.0%]), bronchitis (11 [9.2%]), and stomatitis (10 [8.3%]) were the most common AEs reported. Overall, 25 patients had grade 3 AEs; most frequent was stomatitis (4 [3.3%]). Grade 4 AEs were reported in three (2.5%) patients. A total of 62 (51.7%) patients had suspected drug-related AEs, of which 15 (12.5%) were of grade 3 or 4. In eight (6.7%) patients, AEs led to drug discontinuation. With regard to efficacy, 81 (67.5%) patients had a partial response, 35 (29.2%) had a stable disease, and one (0.8%) had progressive disease. The response was unknown in three (2.5%) patients. CONCLUSION: This study confirms the acceptable safety profile of everolimus in patients with SEGA associated with TSC in a real-world setting. The results further support the efficacy of everolimus in the treatment of SEGA associated with TSC. (EudraCT: 2010-022583-13).

Psychiatric phenotype in neurodevelopmental myoclonus-dystonia is underpinned by abnormality of cerebellar modulation on the cerebral cortex.

Psychiatric symptoms are common in neurodevelopmental movement disorders, including some types of dystonia. However, research has mainly focused on motor manifestations and underlying circuits. Myoclonus-dystonia is a rare and homogeneous neurodevelopmental condition serving as an illustrative paradigm of childhood-onset dystonias, associated with psychiatric symptoms. Here, we assessed the prevalence of psychiatric disorders and the severity of depressive symptoms in patients with myoclonus-dystonia and healthy volunteers (HV). Using resting-state functional neuroimaging, we compared the effective connectivity within and among non-motor and motor brain networks between patients and HV. We further explored the hierarchical organization of these networks and examined the relationship between their connectivity and the depressive symptoms. Comparing 19 patients to 25 HV, we found a higher prevalence of anxiety disorders and more depressive symptoms in the patient group. Patients exhibited abnormal modulation of the cerebellum on the cerebral cortex in the sensorimotor, dorsal attention, salience, and default mode networks. Moreover, the salience network activity was directed by the cerebellum in patients and was related to depressive symptoms. Altogether, our findings highlight the role of the cerebellar drive on both motor and non-motor cortical areas in this disorder, suggesting cerebellar involvement in the complex phenotype of such neurodevelopmental movement disorders.

Association of abnormal explicit sense of agency with cerebellar impairment in myoclonus-dystonia.

Non-motor aspects in dystonia are now well recognized. The sense of agency, which refers to the experience of controlling one's own actions, has been scarcely studied in dystonia, even though its disturbances can contribute to movement disorders. Among various brain structures, the cerebral cortex, the cerebellum, and the basal ganglia are involved in shaping the sense of agency. In myoclonus dystonia, resulting from a dysfunction of the motor network, an altered sense of agency may contribute to the clinical phenotype of the condition. In this study, we compared the explicit and implicit sense of agency in patients with myoclonus dystonia caused by a pathogenic variant of SGCE (DYT-SGCE) and control participants. We utilized behavioural tasks to assess the sense of agency and performed neuroimaging analyses, including structural, resting-state functional connectivity, and dynamic causal modelling, to explore the relevant brain regions involved in the sense of agency. Additionally, we examined the relationship between behavioural performance, symptom severity, and neuroimaging findings. We compared 19 patients with DYT-SGCE and 24 healthy volunteers. Our findings revealed that patients with myoclonus-dystonia exhibited a specific impairment in explicit sense of agency, particularly when implicit motor learning was involved. However, their implicit sense of agency remained intact. These patients also displayed grey-matter abnormalities in the motor cerebellum, as well as increased functional connectivity between the cerebellum and pre-supplementary motor area. Dynamic causal modelling analysis further identified reduced inhibitory effects of the cerebellum on the pre-supplementary motor area, decreased excitatory effects of the pre-supplementary motor area on the cerebellum, and increased self-inhibition within the pre-supplementary motor area. Importantly, both cerebellar grey-matter alterations and functional connectivity abnormalities between the cerebellum and pre-supplementary motor area were found to correlate with explicit sense of agency impairment. Increased self-inhibition within the pre-supplementary motor area was associated with less severe myoclonus symptoms. These findings highlight the disruption of higher-level cognitive processes in patients with myoclonus-dystonia, further expanding the spectrum of neurological and psychiatric dysfunction already identified in this disorder.

Children often present with infantile spasms after herpetic encephalitis.

PURPOSE: To determine what epilepsy types occur after herpetic encephalitis and what are the determinant factors for subsequent infantile spasms. METHODS: We analyzed retrospectively the clinical history of 22 patients, referred to Necker and Saint Vincent de Paul Hospitals (Paris) through the French pediatric epilepsy network from March 1986 to April 2010 and who developed epilepsy some months after herpetic encephalitis. We focused on seizure semiology with video-electroencephalography (EEG) recording, and on neuroradiology and epilepsy follow-up. KEY FINDINGS: Fourteen patients developed pharmacoresistant spasms, and eight developed focal epilepsy, but none had both. The patients who developed spasms were more frequently younger than 30 months at age of onset of epilepsy and had herpetic encephalitis earlier (mean 10.6 months of age) than those who developed focal epilepsy (mean 59.7 and 39.6 months, respectively). Epilepsy follow-up was similar in both groups (8.5 and 11 years, respectively). We found 26 affected cerebral areas; none alone was related to the development of epileptic spasms. SIGNIFICANCE: Risk factors to develop epileptic spasms were to have had herpetic encephalitis early (mean 10 months); to be significantly younger at onset of epilepsy (mean 22.1 months); and to have cerebral lesions involving the insula, the hippocampus, and the temporal pole.

Morbidity and mortality from ataxia-telangiectasia are associated with ATM genotype.

BACKGROUND: Ataxia-telangiectasia (A-T) is a rare genetic disease caused by germline biallelic mutations in the ataxia-telangiectasia mutated gene (ATM) that result in partial or complete loss of ATM expression or activity. The course of the disease is characterized by neurologic manifestations, infections, and cancers. OBJECTIVE: We studied A-T progression and investigated whether manifestations were associated with the ATM genotype. METHODS: We performed a retrospective cohort study in France of 240 patients with A-T born from 1954 to 2005 and analyzed ATM mutations in 184 patients, along with neurologic manifestations, infections, and cancers. RESULTS: Among patients with A-T, the Kaplan-Meier 20-year survival rate was 53.4%; the prognosis for these patients has not changed since 1954. Life expectancy was lower among patients with mutations in ATM that caused total loss of expression or function of the gene product (null mutations) compared with that seen in patients with hypomorphic mutations because of earlier onset of cancer (mainly hematologic malignancies). Cancer (hazard ratio, 2.7; 95% CI, 1.6-4.5) and respiratory tract infections (hazard ratio, 2.3; 95% CI, 1.4-3.8) were independently associated with mortality. Cancer (hazard ratio, 5.8; 95% CI, 2.9-11.6) was a major risk factor for mortality among patients with null mutations, whereas respiratory tract infections (hazard ratio, 4.1; 95% CI, 1.8-9.1) were the leading cause of death among patients with hypomorphic mutations. CONCLUSION: Morbidity and mortality among patients with A-T are associated with ATM genotype. This information could improve our prognostic ability and lead to adapted therapeutic strategies.

Hemidystonia with polymicrogyria is part of ATP1A3-related disorders.

INTRODUCTION: Pathogenic variants in ATP1A3 cause various phenotypes of neurological disorders, including alternating hemiplegia of childhood 2, CAPOS syndrome (cerebellar ataxia, areflexia, pes cavus, optic atrophy, and sensorineural hearing loss) and rapid-onset dystonia-parkinsonism (RDP). Early developmental and epileptic encephalopathy has also been reported. Polymicrogyria has recently been added to the phenotypic spectrum of ATP1A3-related disorders. CASE REPORT: We report here a male patient with early developmental delay who at 12 months presented dystonia of the right arm which evolved into hemidystonia at the age of 2. A cerebral MRI showed bilateral perisylvian polymicrogyria with intact basal ganglia. Whole-exome and whole-genome sequencing analyses identified a de novo new ATP1A3 missense variant (p.Arg914Lys) predicted pathogenic. Hemidystonia was thought not to be due to polymicrogyria, but rather a consequence of this variant. CONCLUSION: This case expands the phenotypic spectrum of ATP1A3-related disorders with a new variant associated with hemidystonia and polymicrogyria and thereby, suggests a clinical continuum between the different phenotypes of this condition.

Age-dependent Mendelian predisposition to herpes simplex virus type 1 encephalitis in childhood.

OBJECTIVE: To test the hypothesis that predisposition to childhood herpes simplex virus (HSV) type 1 encephalitis (HSE) may be determined in part by human genetic factors. STUDY DESIGN: A genetic epidemiologic survey of childhood HSE (onset at age 3 months to 15 years) over a 20-year period (1985-2004) was conducted throughout France (comprising 29 university hospital neuropediatric centers). A total of 85 children fulfilled the diagnostic criteria for inclusion. Family and personal histories were obtained by face-to-face interview for 51 patients. RESULTS: No familial cases of HSE were identified in our survey; however, a high proportion (20%) of the children interviewed had a relevant family history: parental consanguinity (12% of patients), early-onset herpetic keratitis in a first-degree relative (6%), or both (2%). The narrow window of high susceptibility to HSE before age 3 years (62% of patients) further indicates that predisposition to HSE is tightly age-dependent. CONCLUSIONS: This survey suggests that childhood HSE, although sporadic, may result from Mendelian predisposition (from autosomal recessive susceptibility in particular), at least in some children. There likely is incomplete penetrance, however, which may reflect, at least in part, the impact of age at the time of HSV-1 infection.

Early-onset epileptic encephalopathy related to germline PIGA mutations: A series of 5 cases.

The molecular diagnosis of early-onset epileptic encephalopathy (EOEE), an expanding field in child neurology, is becoming increasingly possible thanks to the widespread availability of next-generation sequencing and whole-exome sequencing. In the past 15 years, mutations in STXBP1, KCNQ2, SCN2A, SCN8A and numerous other genes have been reported, giving a more accurate insight for these rare diseases. Among these genes, germline mutations in Phosphatidyl Inositol Glycan A (PIGA) gene were first reported in 2012. Located on Xp22.2, PIGA is involved in the synthesis of GPI (glycosylphosphatidylinositol) which acts as a membrane anchor for different proteins: enzymes, adhesion molecules, regulation of the complement way, and co-receptor in transduction signal. Children suffering from this condition exhibit developmental delay with early-onset epilepsy, severe dysmorphic signs, multi-visceral anomalies and early death in the most severe forms. Here, we report five cases of germline PIGA mutations, with two missense mutations that have not been reported to date. We provide a new insight into the electroclinical phenotype. At the onset, epileptic spasms and focal-onset seizures with upper limbs and ocular involvements were present. Epilepsy proved pharmacoresistant in 4 out of 5 cases. Interictal EEG may be normal at the onset of epilepsy, but abnormalities in electroencephalographic studies were eventually present in all cases. Different types of seizures may be present simultaneously, and epileptic phenotypes evolve with aging.