Alternating Hemiplegia Of Childhood Patients Research Articles

Real life retrospective study of cannabidiol therapy in alternating hemiplegia of childhood

BackgroundMany alternating hemiplegia of childhood (AHC) patients have received Cannabidiol (CBD) but, to our knowledge, there are no published data available. GoalsTest the hypothesis that CBD has favorable effects on AHC spells. MethodsRetrospective review of available data of AHC patients who received CBD. Primary analysis: Clinical Global Impression Scale of Improvement (CGI-I) score for response of AHC spells to CBD with calculation of 95% confidence interval (CI) for rejection of the null hypothesis. Secondary analyses, performed to achieve an understanding of the effect of CBD as compared to flunarizine, were CGI-I scores of 1) epileptic seizures to CBD, 2) AHC spells to flunarizine, 3) epileptic seizures to flunarizine. Also, Mann-Whitney test was done for comparison of CGI-I scores of CBD and flunarizine to both AHC spells and seizures. ResultsWe studied 16 AHC patients seen at Duke University and University of Lyon. CI of CGI-I scores for AHC spells in response to CBD and to flunarizine, each separately, indicated a positive response to each of these two medications: neither overlapped with the null hypothesis score, 4, indicating significant positive responses with p < 0.05 for both. These two scores also did not differ (p = 0.84) suggesting similar efficacy of both: CBD score was 2 ± 1.1 with a 95% CI of 1.5–2.6 and flunarizine score was 2.3 ± 1.3 with a 95% CI of 1.7–3.1. In patients who had seizures, CI calculations indicated a positive effect of CBD on seizure CGI scores but not of flunarizine on seizure scores. CBD was well tolerated with no patients discontinuing it due to side effects and with some reporting positive behavioral changes. ConclusionOur study indicates a real-life positive effect of CBD on AHC type spells.

Characteristics of non-sleep related apneas in children with alternating hemiplegia of childhood

BackgroundNon-sleep related apnea (NSA) has been observed in alternating hemiplegia of childhood (AHC) but has yet to be characterized. GoalsInvestigate the following hypotheses: 1) AHC patients manifest NSA that is often severe. 2) NSA is usually triggered by precipitating events. 3) NSA is more likely in patients with ATP1A3 mutations. MethodsRetrospective review of 51 consecutive AHC patients (ages 2–45 years) enrolled in our AHC registry. NSAs were classified as mild (not needing intervention), moderate (needing intervention but not perceived as life threatening), or severe (needing intervention and perceived as life threatening). Results19/51 patients (37 %) had 52 NSA events (6 mild, 11 moderate, 35 severe). Mean age of onset of NSA (± Standard Error of the Mean (SEM)): 3.8 ± 1.5 (range 0–24) years, frequency during follow up was higher at younger ages as compared to adulthood (year 1: 2.2/year, adulthood: 0.060/year). NSAs were associated with triggering factors, bradycardia and with younger age (p < 0.008 in all) but not with mutation status (p = 0.360). Triggers, observed in 17 patients, most commonly included epileptic seizures in 9 (47 %), anesthesia, AHC spells and intercurrent, stressful, conditions. Management included use of pulse oximeter at home in nine patients, home oxygen in seven, intubation/ventilatory support in seven, and basic CPR in six. An additional patient required tracheostomy. There were no deaths or permanent sequalae. ConclusionsAHC patients experience NSAs that are often severe. These events are usually triggered by seizures or other stressful events and can be successfully managed with interventions tailored to the severity of the NSA.

Abstract 12942: The D801N Variant in ATP1A3 -Encoded Na/K-atpase Alpha 3 Shortens the Cardiac Myocyte Action Potential and Increases Risk for Calcium Mediated Arrhythmias

Background: Alternating hemiplegia of childhood (AHC) is a rare de novo syndrome that manifests with episodic hemiplegia, seizures, dystonia, and, notably, sudden unexplained death. Gene positive patients carry a pathogenic variant in the ATP1A3 -encoded Na/K ATPase alpha 3 isoform (ATP1A3), and the variant D801N is the most common pathogenic variant. Our group recently found that AHC patients with ATP1A3-D801N missense have short QTc and are at risk of ventricular fibrillation. Hypothesis: We hypothesized that the D801N variant results in reduced ATPase function leading to Ca 2+ overload resulting in shortened repolarization time and increased arrhythmogenic risk. Methods: We differentiated iPSCs into cardiomyocytes from an AHC patient hosting the ATP1A3-D801N variant (iPSC-CM D801N ), and an ostensibly healthy individual (iPSC-CM WT ). Patch clamp was conducted to determine APD90, and the ratio of cells with delayed after depolarization events (DADs). iPSC-CM WT were perfused with 10 -7 M ouabain, an ATP1A3 inhibitor, and APD90 and DADs were measured. SR store ([Ca 2+ ] SR ) was measured with Cal-520 dye under 10 mM caffeine. Resting [Ca 2+ ] i was measured with Fura-2 dye, and Na/Ca exchanger (NCX) peak current was measured as Ni 2+ sensitive current in a stepwise voltage-clamp protocol. Results: iPSC-CM D801N APD90 was shorter 40% than iPSC-CM WT . IPSC-CM WT treated with ouabain had 17% shorter APD90 than vehicle. iPSC-CM D801N had DADs (3/11 cells) when iPSC-CM WT (0/24) did not, and 6/12 ouabain treated iPSC-CM WT had DADs vs vehicle treated (0/18). Post caffeine, iPSC-CM D801N had higher [Ca 2+ ] SR than iPSC-CM WT . Finally, iPSC-CM D801N had higher resting [Ca 2+ ] i than iPSC-CM WT and iPSC-CM D801N had higher peak NCX current density at +80mV but no difference at RMP. Conclusions: Our results show that both iPSC-CM D801N and ouabain-treated iPSC-CM WT , have a shorter APD compared to WT controls and exhibit DADs. This is associated with higher NCX-mediated influx of Ca 2+ and increased intracellular Ca 2+ . Our findings highlight the emerging role of ATP1A3-D801N in creating a myocardium vulnerable to arrhythmias.

Characterization of sedation and anesthesia complications in patients with alternating hemiplegia of childhood.

Alternating hemiplegia of childhood (AHC) pathophysiology suggests predisposition to sedation and anesthesia complications. Hypotheses: 1) AHC patients experience high rates of sedation-anesthesia complications. 2) ATP1A3 mutation genotype positivity, age, and AHC severity correlate with more severe complications. 3) Prior short QTc correlates with cardiac rhythm complications. Analysis of 34 consecutive AHC patients who underwent sedation or anesthesia. Classification of complications: mild (not requiring intervention), moderate (intervention), severe (intervention, risk for permanent injury or potential life-threatening emergency). Fisher Exact test, Spearman correlations. These patients underwent 129 procedures (3.79±2.75 procedures/patient). Twelve (35%) experienced complications during at least one procedure. Fourteen/129 procedures (11%) manifested one or more complications (2.3% mild, 7% moderate, 1.6% severe). Of the total 20 observed complications, six (33.3%) were severe: apneas (2), seizures (2), bradycardia (1), ventricular fibrillation that responded to resuscitation (1). Moderate complications: non-life-threatening bradycardias, apneas, AHC spells or seizures. Complications occurred during sedation or anesthesia and during procedures or recovery periods. Patients with disease-associated ATP1A3 variants were more likely to have moderate or severe complications. There was no correlation between complications and age or AHC severity. Presence of prior short QTc correlated with cardiac rhythm complications. After this series was analyzed, another patient had severe recurrent laryngeal dystonia requiring tracheostomy following anesthesia with intubation. During sedation or anesthesia, AHC patients, particularly those with ATP1A3 variants and prior short QTc, are at risk for complications consistent with AHC pathophysiology. Increased awareness is warranted during planning, performance, and recovery from such procedures.

Hypothalamic-pituitary dysfunction in alternating hemiplegia of childhood

Background Many central nervous system disorders result in hypothalamic-pituitary (HP) axis dysfunction. Alternating Hemiplegia of Childhood (AHC) is usually caused by mutations in the ATP1A3 subunit of the Na+/K+ ATPase, predominantly affecting GABAergic interneurons. GABAergic interneurons and the ATP1A3 subunit are both important for function of the hypothalamus. However, whether HP dysfunction occurs in AHC and, if so, how such dysfunction manifests remains to be investigated. Methods We conducted a retrospective review of a cohort of 50 consecutive AHC patients for occurrence of HP related manifestations and analyzed the findings of the 6 patients, from that cohort, with such manifestations. Results Six out of 50 AHC patients manifested HP dysfunction. Three of these patients were mutation positive and 3 were mutation negative. Of the 6 patients with HP dysfunction, 3 had central precocious puberty. A fourth had short stature due to growth hormone deficiency. Two other patients had recurrent episodes of fever of unknown origin (FUO) diagnosed, after workups, as being secondary to central fever. All patients were evaluated and co-managed by pediatric neurology and endocrinology or rheumatology. Conclusion AHC was associated with HP dysfunction in about 12% of patients. Awareness of such dysfunction is important for anticipatory guidance and management particularly in the case of FUO which often presents a diagnostic dilemma. Our findings are also consistent with current understandings of the underlying pathophysiology of AHC and of the HP axis.

Magnetic resonance imaging volumetric analysis in patients with Alternating hemiplegia of childhood: A pilot study.

Quantitative MRI is increasingly being used as a biomarker in neurological disorders. Cerebellar atrophy occurs in some Alternating Hemiplegia of Childhood (AHC) patients. However, it is not known if cerebellar atrophy can be a potential biomarker in AHC or if quantitative MRI is a reliable method to address this question. Here we determine the reproducibility of an MRI-volumetrics method to investigate brain volumes in AHC and apply it to a population of 14 consecutive AHC patients (ages 4-11 years). We studied method reproducibility in the first 11 patients and then performed correlation of cerebellar volumes, relative to published normal population means, with age in all 14. We used FreeSurfer 6.0.0 to automatically segment MRI images, then performed manual resegmentation correction by two different observers. No significant differences were observed in any of ten brain regions between the two reviewers: p>.591 and interclass Correlation Coefficient (ICC) ≥0.975 in all comparisons. Additionally, there were no significant differences between the means of the two reviewers and the automatic segmentation values: p≥.106 and ICC ≥0.994 in all comparisons. We found a negative correlation between cerebellar volume and age (R=-0.631, p=.037), even though only one patient showed any cerebellar atrophy upon formal readings of the MRIs by neuroradiology. Sample size did not allow us to rule out potential confounding variables. Thus, findings from this cross-sectional study should be considered as exploratory. Our study supports the prospective investigation of quantitative MRI-volumetrics of the cerebellum as a potential biomarker in AHC.

Genotype-phenotype correlation in patients with alternating hemiplegia of childhood

Objective: To explore the correlation between ATP1A3 genotype and phenotype in children with alternating hemiplegia of childhood (AHC). Methods: This was a retrospective study. The clinical data and peripheral blood DNA of AHC patients were collected in Peking University First Hospital from August 2005 to December 2017. ATP1A3 gene mutations were screened by Sanger sequencing or next generation sequencing (NGS). AHC patients were divided into difference groups according to different hotspot mutations. SPSS 23.0 was used to analyze the correlation between genotype and phenotype. Variance analysis was used to compare the measurement data between groups. Chi square test was used to compare the categorical data between groups. Kruskal-Wallis test was used to compare the unidirectional ordered data between groups. Least-significant difference(LSD) was used to compare the data between two groups. Results: A total of 119 AHC patients were recruited, including 68 males and 51 females. The onset age of 113 (95.0%) patients was within 18 months. There were 119 cases (100.0%) with hemiplegic seizures, 109 cases (91.6%) with abnormal eyeball movements, 104 cases (87.4%) with dystonia, 31 cases (26.1%) with autonomic neurological symptoms, 31 cases (26.1%) with epileptic seizures and 117 cases (98.3%) with long-term developmental delay. In 113 patients (95.0%) with ATP1A3 gene mutations, 111 were de novo mutation and 2 were genetic mutations. A total of 39 mutation types were found, including 37 missense mutations and 2 deletion mutations. Seventeen of them were novel mutations. The three hotspot mutations were D801N (n=34, 30.1%), E815K (n=20, 17.7%) and G947R (n=13, 11.5%). The age of onset of D801N and E815K were earlier than G947R ((3.1±2.1)and (2.3±2.3)vs.(6.4±7.7) months, P=0.004 and 0.003). The age of first hemiplegic events of D801N and E815K were earlier than G947R((6.4±3.1) and (6.8±3.3) vs. (11.4±10.1) months, P=0.004 and 0.016). More patients with E815K mutations presented epilepsy than those with D801N (P=0.003) and G947R (P=0.001). More patients with E815K mutations presented greater motor and intellectual disability than the patients with D801N (P=0.001) and G947R mutations (P=0.001). Conclusions: ATP1A3 gene is the main causative gene of AHC. Three hotspot mutations, D801N, E815K and G947R, were found. Hotspot mutation E815K is associated with the most severe phenotype, which presented an earlier age at the time of the first paroxysmal manifestation and first hemiplegic event, severer developmental delay and a greater proportion of epilepsy.

Diagnosis and Treatment of Alternating Hemiplegia of Childhood.

The diagnosis and treatment of patients with Alternating Hemiplegia of Childhood (AHC) and related disorders should be provided by a multidisciplinary team experienced with the spectrum of presentations of this disease, with its related disorders, with its complex and fluctuating manifestations, and with cutting edge advances occurring in the field. Involvement in research to advance the understanding of this disease and partnership with international collaborators and family organizations are also important. An example of such an approach is that of The Duke AHC and Related Disorders Multi-Disciplinary Clinic and Program, which, in partnership with the Cure AHC Foundation, has developed and applied this approach to patients seen since early 2013. The program provides comprehensive care and education directly to AHC patients and their families and collaborates with referring physicians on the care of patients with AHC whether evaluated at Duke clinics or not. It also is involved in clinical and basic research and in collaborations with other International AHC Research Consortium (IAHCRC) partners. The clinic is staffed with physicians and experts from Neurology, Cardiology, Child Behavioral Health, Medical Genetics, Neurodevelopment, Neuropsychology, Nursing, Physical and Occupational Therapies, Psychiatry, Sleep Medicine, and Speech/Language Pathology. Patients are seen either for full comprehensive evaluations that last several days or for targeted evaluations with one or few appointments.

Clinical features and ATP1A3 gene mutations in alternating hemiplegia of childhood patients with epilepsy

Objective To analyze the clinical features and the genotype-phenotype correlations of ATP1A3 mutations in alternating hemiplegia of childhood (AHC) patients with epilepsy. Methods The clinical data and peripheral blood of AHC patients in Department of Pediatrics, Peking University First Hospital from August 2005 to November 2015 were collected and analyzed.Mutations in ATP1A3 were screened by Sanger sequencing and PCR amplification. Results A total of 93 AHC patients were recruited.Fourteen patients (15.1%) had concurrent epilepsy.The age of seizure onset ranged from 6 hours to 6 years.Focal seizure was observed in 9 cases, generalized tonic-clonic seizures (GTCS) in 7 cases, and atypical absence was found in 1 case.Three of those patients had 2 types, and 11 patients experienced status epilepticus during the course.Electroencephalography (EEG) was performed in 13 cases.EEG were abnormal in 5 patients.The background activity was slow in 5 cases.Multiple focal or generalized spikes were found in 3 patients and diffused slow waves in 1 patient.Nonconvulsive status epilepticus(atypical absence status epilepticus) was monitored in 1 patient, whose actions were reduced and response slowed in the next 35 min while the EEG monitored 2.0-2.5Hz generalized spike and waves.EEG were normal in 8 cases.ATP1A3 mutations were identified in 14 patients with epilepsy.Four types of missense mutations were found, including mutation E815K in 11 patients.Mutation D801N, L839P, and E277K were detected in one patient, respectively.In 93 AHC patients, 18 patients were found with E815K mutation, and 11 of them (61.1%) had epilepsy. Conclusions The age of seizure onset in AHC patients could happen as early as neonatal period.Focal seizures and GTCS are the two most common types in AHC patients with epilepsy and these patients often experienced status epilepticus.Most of their interictal EEG were normal.AHC patients with epilepsy are more likely to carry ATP1A3 gene E815K mutation. Key words: Alternating hemiplegia of childhood; Epilepsy; Focal seizure; ATP1A3 gene

ATP1A3 gene mutations in patients with alternating hemiplegia of childhood

To analyze the ATP1A3 mutations in patients with alternating hemiplegia of childhood (AHC) and recognize its value in diagnosing atypical cases. Data of all AHC patients seen at Peking University First Hospital from August 2005 to November 2014 were prospectively collected. Clinical information of the AHC patients and their family members were collected and analyzed. Genomic DNAs were extracted from their peripheral blood. Mutations in ATP1A3 were screened by Sanger sequencing after PCR. A total of 78 AHC patients were recruited, including 50 males and 28 females. Only three patients had family history of AHC. The first family case had affected mother with AHC; the second family case was the older one of a monozygotic male twins with AHC but their parents were normal; the third family case had a sister with AHC but their parents were normal. The age of onset ranged from six hours to eight years and six months (median: 4 months). According to the Aicardi's clinical diagnostic criteria, 72 patients were considered as typical AHC cases and the other six patients were considered as atypical AHC cases for their age of onset was older than 18 months. Twenty-seven different missense ATP1A3 mutations were detected in 71 (91.0%, 71/78) patients with AHC, including 66 typical and 5 atypical cases. 11 novel ATP1A3 mutations were first reported. ATP1A3 mutations were identified in the three AHC cases with family history. Parental analysis verified that the ATP1A3 mutation of 63 patients (95.5%, 63/66) were de novo origin except lack of five unavailable maternal or paternal genomic DNA. Mutation D801N was found in 20 cases (28.2%), and E815K in 12 cases (16.9%). In the six atypical AHC patients, ATP1A3 mutations were detected in five of them. ATP1A3 was the major causative gene of AHC, and mutations were identified as de novo mostly. ATP1A3 mutations in AHC had mutational hotspot, and the most common mutations were D801N and E815K. ATP1A3 mutation screening is helpful for the genetic and definite diagnosis of the atypical AHC cases.

Transgenic rescue of phenotypic deficits in a mouse model of alternating hemiplegia of childhood.

Missense mutations in ATP1A3 encoding Na+,K+-ATPase α3 are the primary cause of alternating hemiplegia of childhood (AHC). Most ATP1A3 mutations in AHC lie within a cluster in or near transmembrane α-helix TM6, including I810N that is also found in the Myshkin mouse model of AHC. These mutations all substantially reduce Na+,K+-ATPase α3 activity. Herein, we show that Myshkin mice carrying a wild-type Atp1a3 transgene that confers a 16 % increase in brain-specific total Na+,K+-ATPase activity show significant phenotypic improvements compared with non-transgenic Myshkin mice. Interventions to increase the activity of wild-type Na+,K+-ATPase α3 in AHC patients should be investigated further.Electronic supplementary materialThe online version of this article (doi:10.1007/s10048-015-0461-1) contains supplementary material, which is available to authorized users.

Alternating Hemiplegia of Childhood: Retrospective Genetic Study and Genotype-Phenotype Correlations in 187 Subjects from the US AHCF Registry.

Mutations in ATP1A3 cause Alternating Hemiplegia of Childhood (AHC) by disrupting function of the neuronal Na+/K+ ATPase. Published studies to date indicate 2 recurrent mutations, D801N and E815K, and a more severe phenotype in the E815K cohort. We performed mutation analysis and retrospective genotype-phenotype correlations in all eligible patients with AHC enrolled in the US AHC Foundation registry from 1997-2012. Clinical data were abstracted from standardized caregivers’ questionnaires and medical records and confirmed by expert clinicians. We identified ATP1A3 mutations by Sanger and whole genome sequencing, and compared phenotypes within and between 4 groups of subjects, those with D801N, E815K, other ATP1A3 or no ATP1A3 mutations. We identified heterozygous ATP1A3 mutations in 154 of 187 (82%) AHC patients. Of 34 unique mutations, 31 (91%) are missense, and 16 (47%) had not been previously reported. Concordant with prior studies, more than 2/3 of all mutations are clustered in exons 17 and 18. Of 143 simplex occurrences, 58 had D801N (40%), 38 had E815K (26%) and 11 had G937R (8%) mutations. Patients with an E815K mutation demonstrate an earlier age of onset, more severe motor impairment and a higher prevalence of status epilepticus. This study further expands the number and spectrum of ATP1A3 mutations associated with AHC and confirms a more deleterious effect of the E815K mutation on selected neurologic outcomes. However, the complexity of the disorder and the extensive phenotypic variability among subgroups merits caution and emphasizes the need for further studies.

Somatosensory system hyperexcitability in alternating hemiplegia of childhood.

Alternating hemiplegia of childhood (AHC) is a rare neurological disease characterized by recurrent paroxysmal attacks of hemiplegia. The aim of the study was to assess the recovery cycle of the somatosensory evoked potentials (SEPs) in a group of AHC patients. Seven AHC patients and 10 control age-matched subjects (CS) were recruited. Right and left median nerve SEPs were recorded. The somatosensory system excitability was assessed by calculating the SEP changes after paired electrical stimuli. All patients were studied during the interictal phase, whilst four patients were studied also during the ictal phase. In AHC patients during the interictal phase, the amplitudes of the cervical N13 and of the cortical N20, P24 and N30 responses showed a faster recovery than in CS. In AHC patients during the ictal phase, the cortical N20 recovery cycle was prolonged compared with the interictal phase. A shortened SEP recovery cycle in AHC during the interictal phase suggests multilevel somatosensory system hyperexcitability in AHC. A partial recovery of this phenomenon during the ictal phase possibly reflects a functional reset of the somatosensory system. Overall, there is a disinhibition of the somatosensory system in AHC, a functional change of brain function associated with a possible involvement of the Na(+) /K(+) channels. This abnormality and its partial recovery during the attacks might be linked to the pathophysiological and genetic mechanisms of the disease.

ATP1A3 mutations and genotype-phenotype correlation of alternating hemiplegia of childhood in Chinese patients.

Alternating hemiplegia of childhood (AHC) is a rare and severe neurological disorder. ATP1A3 was recently identified as the causative gene. Here we report the first genetic study in Chinese AHC cohort. We performed whole-exome sequencing on three trios and three unrelated patients, and screened additional 41 typical cases and 100 controls by PCR-Sanger sequencing. ATP1A3 mutations were detected in 95.7% of typical AHC patients. At least 93.3% were de novo. Four late onset, atypical AHC patients were also mutation positive, suggesting the need for testing ATP1A3 mutations in atypical cases. Totally, 13 novel missense mutations (T370N, G706R, L770R, T771N, T771I, S772R, L802P, D805H, M806K, P808L, I810N, L839P and G893R) were identified in our study. By homology modeling of the mutant protein structures and calculation of an extensive list of molecular features, we identified two statistically significant molecular features, solvent accessibility and distance to metal ion, that distinguished disease-associated mutations from neutral variants. A logistic regression classifier achieved 92.9% accuracy by the average of 100 times of five-fold cross validations. Genotype-phenotype correlation analysis showed that patients with epilepsy were more likely to carry E815K mutation. In summary, ATP1A3 is the major pathogenic gene of AHC in Chinese patients; mutations have distinctive molecular features that discriminate them from neutral variants and are correlated with phenotypes.

A novel SLC2A1 mutation linking hemiplegic migraine with alternating hemiplegia of childhood

Hemiplegic migraine (HM) and alternating hemiplegia of childhood (AHC) are rare episodic neurological brain disorders with partial clinical and genetic overlap. Recently, ATP1A3 mutations were shown to account for the majority of AHC patients. In addition, a mutation in the SLC2A1 gene was reported in a patient with atypical AHC. We therefore investigated whether mutations in these genes may also be involved in HM. Furthermore, we studied the role of SLC2A1 mutations in a small set of AHC patients without ATP1A3 mutations. We screened 42 HM patients (21 familial and 21 sporadic patients) for ATP1A3 and SLC2A1 mutations. In addition, four typical AHC patients and one atypical patient with overlapping symptoms of both disorders were screened for SLC2A1 mutations. A pathogenic de novo SLC2A1 mutation (p.Gly18Arg) was found in the atypical patient with overlapping symptoms of AHC and hemiplegic migraine. No mutations were found in the HM and the other AHC patients. Screening for a mutation in the SLC2A1 gene should be considered in patients with a complex phenotype with overlapping symptoms of hemiplegic migraine and AHC.

Application of Magnetic Resonance Spectroscopy in Patients with Alternating Hemiplegia of Childhood: Findings on Metabolic Dysfunctions

Alternating hemiplegia of childhood (AHC) is a rare neurodevelopmental syndrome of uncertain etiology. Although the use of magnetic resonance spectroscopy (MRS) for the study of neurologic diseases has grown rapidly over the past decade, its use for AHC patients is quite new. This study was aimed at investigating changes of brain metabolites in patients with alternating hemiplegia of childhood (AHC) during the hemiplegic ictal phases and interictal phases by proton magnetic resonance spectroscopy ((1)H-MRS). (1)H-MRS was used in AHC patients during the hemiplegic ictal phases and interictal phases to evaluate functional activity in certain brain regions. A total of 10 unmedicated, healthy volunteers served as controls. N-acetylaspartate (NAA)/Creatine(Cr) ratio of the frontal lobes, basal ganglia, and temporal lobes in contralateral hemiplegic hemisphere of AHC patients during the ictal phases was significantly lower than that in AHC patients during interictal phases and control subjects. Significantly increased choline-containing compounds (Cho)/Cr were obtained in corresponding regions. These findings suggest neuronal metabolic dysfunctions in frontal lobes, temporal lobes and basal ganglia in AHC patients during ictal phases that perhaps are involved in the pathogenesis of AHC.

Alternating hemiplegia of childhood in Denmark: Clinical manifestations and ATP1A3 mutation status

Alternating hemiplegia of childhood (AHC) is a rare neurodevelopmental disorder characterized by early-onset recurrent distinctive hemiplegic episodes commonly accompanied by other paroxysmal features and developmental impairment. De novo mutations in ATP1A3 were recently identified as a genetic cause of AHC. To describe the entire Danish cohort of paediatric AHC patients we approached neuropaediatricians nationwide. All currently acknowledged Danish patients ≤16 years with AHC were genetically tested and seen by the same child neurologist (PU). Ten patients; seven girls and three boys were identified. Mean present age was 10.0 years (range 1–16). Mean age at presentation was 7.4 months (range 1–18 months). Sequencing of ATP1A3 in all ten patients revealed a pathogenic mutation in seven. Two females with moderate psychomotor impairment were heterozygous for the known p.G947R mutation, whereas one severely retarded boy was heterozygous for the common p.E815K mutation. The prevalent p.D801N mutation was identified in two moderate to severely retarded children. Interestingly, in a set of monochorionic male twins a novel p.D801E mutation was identified, underscoring that the asparagine at position 801 is a mutation hotspot. Three girls aged 5–13 years did not reveal any ATP1A3 mutations. They were rather mildly clinically affected and displayed a normal or near-normal psychomotor development. This is the first study of AHC in the Danish paediatric population. The patients harboured a wide range of psychomotor difficulties. Patients with no mutation detected tended to be less severely affected. Prevalence was approximately 1 per 100,000 children.

Functional studies and proteomics in platelets and fibroblasts reveal a lysosomal defect with increased cathepsin-dependent apoptosis in ATP1A3 defective alternating hemiplegia of childhood

Alternating hemiplegia of childhood (AHC) is a rare syndrome with repeated hemiplegic episodes, paroxysmal events and global neurological impairment. Recently, heterozygous de novo ATP1A3 missense mutations have been identified in AHC patients, but the underlying pathogenesis mechanism remains unknown. Mutation analysis of ATP1A3 in 9 unrelated AHC cases revealed mostly D801N or E815K variants. As platelets represent a good cellular model to study defects in neuropathologies, morphological and functional experiments were performed in these subjects. Platelets from the AHC patients presented with structural and functional abnormalities of granules positive for the lysosomal marker CD63. Similar structural granule abnormalities were detected in patients' fibroblasts. Proteomic analysis of platelets and fibroblasts showed a total of 93 differentially expressed proteins in AHC mainly involved in metabolism. Interestingly, 7 of these proteins were detected in both cell types, including the lysosomal protein cathepsin. AHC fibroblasts revealed significantly increased levels of activated cathepsin B, which induces a stronger activation of apoptosis. Our study is the first to link ATP1A3 defects in AHC to a platelet and fibroblast lysosomal defect with evidence of increased apoptosis. Further studies are needed to define how this lysosomal defect is related to decreased ATPase activity. Biological Significance Only recently, the genetic cause of AHC was identified as heterozygous ATP1A3 mutations, but the underlying pathophysiological mechanism still remains unknown. By performing functional, morphological and proteomic studies in AHC patients we found a structural and functional granule defect in AHC platelets and fibroblasts that was specifically found in granules positive for the lysosomal marker CD63. In particular, proteomics identified several differentially expressed proteins in fibroblasts and platelets from AHC cases that are predicted to have an important role in cell function and maintenance, a pathway typically attributed to lysosomes. The lysosomal protein cathepsin was found to be differentially expressed in both platelets and fibroblasts of AHC patients, inducing a stronger activation of mainly the intrinsic apoptosis. Despite the precise mechanism for the increased lysosomal cathepsin B-dependent apoptosis detected in AHC in relation to impaired ATP1A3 deserves further studies, we could here show some evidence for a defective regulation of apoptosis in AHC, a disease that still has no biochemical or neuroradiological parameters for diagnosis.

Profiles of blood biomarkers in alternating hemiplegia of childhood – Increased MMP-9 and decreased substance P indicates its pathophysiology

Alternating hemiplegia of childhood (AHC) is a rare disorder characterized by repeated plegic attacks, movement disorders, autonomic phenomena, and developmental delay. To obtain insights into the pathophysiology of AHC, we determined the concentrations of matrix metalloproteinase-9 (MMP-9), tissue inhibitor of MMP-1 (TIMP-1), calcitonin gene-related peptide (CGRP), and substance P (SP) in the serum/plasma of AHC patients (n=6) and control subjects (n=11) by performing enzyme-linked immunosorbent assay (ELISA).Decreased levels of serum SP (382±161pg/ml), increased levels of plasma MMP-9 (111.0±99.3ng/mL) and increased MMP-9/TIMP-1 ratio (0.65±0.44) were revealed, compared to those in control subjects (SP: 620±223pg/mL, p<0.05; MMP-9: 33.5±20.3ng/mL, p<0.05; MMP-9/TIMP-1 ratio 0.21±0.09, p<0.005). Serum CGRP levels in AHC patients (32.6±14.4pg/mL) were comparable to those in control subjects (37.0±17.0pg/mL). Increased MMP-9 levels may be linked to the vascular insult and is common in migraineurs. However, because AHC patients showed different changes in SP and CGRP levels compared to those shown by migraineurs, these results suggest that AHC has a pathomechanism different from the hypothesis of trigeminovascular theory. Decreased SP may represent the autonomic dysfunction in AHC, for which an etiology with progressive neuronal damage can be hypothesized.

Evolution of hemiplegic attacks and epileptic seizures in alternating hemiplegia of childhood

To delineate the evolution of non-epileptic and epileptic paroxysmal events in alternating hemiplegia of childhood (AHC), we reviewed clinical information of nine patients (4-40 years) with AHC. Paroxysmal abnormal ocular movements, head turning, and tonic, clonic, or myoclonic limb movements were the initial symptoms (birth-8m) in each patient. Ictal electroencephalography (EEG) of these episodes, as well as hemiplegic periods that accompanied these symptoms later in infancy showed unremarkable findings or generalized slow background activity. Presumptive epileptic seizures appeared at 2-16y in seven patients: generalized tonic, clonic, myoclonic, tonic-clonic, or complex partial seizures often accompanied by cyanosis or prolonged respiratory arrest. Ictal EEGs recorded in four patients revealed focal slow or fast activities during facial or limb twitching, and widespread sharp waves or polyspike-wave activities during clonic/myoclonic seizures. Four patients with neonatal disease onset showed lower psychomotor developmental achievements compared with other patients, and experienced repeated status epilepticus followed by progressive deterioration. Cerebellar atrophy and hippocampal high signal changes on magnetic resonance imaging were common to this group with severe phenotypes. Apart from the paroxysmal motor symptoms accompanying the hemiplegic episodes, many AHC patients suffer from true epilepsies during childhood. Status epilepticus in AHC is linked to severe outcome with psychomotor deterioration. The variations in clinical phenotypes may imply multiple causative genes for AHC. This variation should be considered while managing patients with this disorder.