Metabolic shift underlies recovery in reversible infantile respiratory chain deficiency.

Reversible infantile respiratory chain deficiency (RIRCD) is a rare mitochondrial myopathy leading to severe metabolic disturbances in infants, which recover spontaneously after 6-months of age. RIRCD is associated with the homoplasmic m.14674T>C mitochondrial DNA mutation; however, only ~ 1/100 carriers develop the disease. We studied 27 affected and 15 unaffected individuals from 19 families and found additional heterozygous mutations in nuclear genes interacting with mt-tRNAGlu including EARS2 and TRMU in the majority of affected individuals, but not in healthy carriers of m.14674T>C, supporting a digenic inheritance. Our transcriptomic and proteomic analysis of patient muscle suggests a stepwise mechanism where first, the integrated stress response associated with increased FGF21 and GDF15 expression enhances the metabolism modulated by serine biosynthesis, one carbon metabolism, TCA lipid oxidation and amino acid availability, while in the second step mTOR activation leads to increased mitochondrial biogenesis. Our data suggest that the spontaneous recovery in infants with digenic mutations may be modulated by the above described changes. Similar mechanisms may explain the variable penetrance and tissue specificity of other mtDNA mutations and highlight the potential role of amino acids in improving mitochondrial disease.

Hospital admissions from the emergency department of adult patients affected by myopathies.

BACKGROUND AND PURPOSE: Myopathies are associated with classic signs and symptoms, but also with possible life-threatening complications that may require assistance in an emergency setting. This phenomenon is understudied in the literature. We aimed to assess the presentation, management, and outcomes of clinical manifestations potentially related to a muscle disorder requiring referral to the adult emergency department (ED) and hospitalization. METHODS: Anonymized patient data retrieved using the International Classification of Diseases, Ninth Revision codes related to muscle disorders over 4 years were retrospectively analyzed. Medical reports were evaluated to extract demographic and clinical variables, along with outcomes. Two groups were defined based on the presence (known diagnosis [KD] group) or absence (unknown diagnosis [UD] group) of a diagnosed muscle disorder at arrival. RESULTS: A total of 244 patients were included, 51% of whom were affected by a known myopathy, predominantly limb-girdle muscular dystrophies and myotonic dystrophies. The main reasons for ED visits in the KD group were respiratory issues, worsening of muscle weakness, and gastrointestinal problems. Heart complications were less prevalent. In the UD group, 27 patients received a new diagnosis of a specific primary muscle disorder after the ED access, mostly an inflammatory myopathy. Death during hospitalization was recorded in 26 patients, with a higher rate in the KD group and in patients affected by mitochondrial and inflammatory myopathies. Sepsis and dyspnea were associated with increased death risk. CONCLUSIONS: Respiratory complications are the most common reason for myopathic patients accessing the ED, followed by gastrointestinal issues. Infections are severe threats and, once hospitalized, these patients have relatively high mortality.

Management of seizures in patients with primary mitochondrial diseases: consensus statement from the InterERNs Mitochondrial Working Group.

BACKGROUND AND PURPOSE: Primary mitochondrial diseases (PMDs) are common inborn errors of energy metabolism, with an estimated prevalence of one in 4300. These disorders typically affect tissues with high energy requirements, including heart, muscle and brain. Epilepsy may be the presenting feature of PMD, can be difficult to treat and often represents a poor prognostic feature. The aim of this study was to develop guidelines and consensus recommendations on safe medication use and seizure management in mitochondrial epilepsy. METHODS: A panel of 24 experts in mitochondrial medicine, pharmacology and epilepsy management of adults and/or children and two patient representatives from seven countries was established. Experts were members of five different European Reference Networks, known as the Mito InterERN Working Group. A Delphi technique was used to allow the panellists to consider draft recommendations on safe medication use and seizure management in mitochondrial epilepsy, using two rounds with predetermined levels of agreement. RESULTS: A high level of consensus was reached regarding the safety of 14 out of all 25 drugs reviewed, resulting in endorsement of National Institute for Health and Care Excellence guidelines for seizure management, with some modifications. Exceptions including valproic acid in POLG disease, vigabatrin in patients with γ-aminobutyric acid transaminase deficiency and topiramate in patients at risk for renal tubular acidosis were highlighted. CONCLUSIONS: These consensus recommendations describe our intent to improve seizure control and reduce the risk of drug-related adverse events in individuals living with PMD-related epilepsy.

Efficacy of galcanezumab in proline-rich transmembrane protein 2 (PRRT2)-associated familial hemiplegic migraine: A case series.

BACKGROUND: Familial hemiplegic migraine (FHM) is a rare subtype of migraine with aura. Variants in calcium voltage-gated channel subunit alpha1 A (CACNA1A), ATPase Na+/K+ transporting subunit alpha 2 (ATP1A2), and sodium voltage-gated channel alpha subunit 1 (SCN1A) genes have a well-established association with the development of FHM. Recent studies suggest that other genes may also have a significant role in the pathogenesis of FHM, including proline-rich transmembrane protein 2 (PRRT2). To our knowledge, there are currently no documented reports of the use of monoclonal antibodies targeting calcitonin gene-related peptide in FHM caused by a specific identified genetic mutation - and in particular not in FHM associated with PRRT2 mutations. The aim of our work is to describe the efficacy of galcanezumab as a prophylaxis treatment on patients from an Italian family consisting of six patient carriers of a PRRT2 pathogenic variant. METHODS: Inclusion criteria for treatment eligibility consisted of a confirmed diagnosis of genetically confirmed FHM as defined by the International Classification of Headache Disorders, third edition, number of headache days/month ≥4, and at least two previously failed migraine prophylaxis treatments. We evaluated clinical data of patients treated with galcanezumab regarding number of headache days/month, frequency of aura, disability caused by HM using the Migraine Disability Assessment (MIDAS), attack severity through a numerical rating scale (NRS), acute medications intake, and response to acute medications at baseline (t0) and after 3 (t1) and 6 (t2) months of treatment. RESULTS: Three out of six family members met inclusion criteria for treatment with galcanezumab. The average number of headache days/month, acute medications, and MIDAS significantly decreased in all treated patients, as well as the average NRS score. Aura frequency reduced by ≥50% compared to the baseline in all three patients. No adverse events related to galcanezumab were reported. CONCLUSION: Galcanezumab is a valid and well-tolerated treatment option in PRRT2-associated FHM.

Clinical characteristics and treatment approach of established New-Onset status epilepticus (eNOSE): A Real-World multicenter experience.

INTRODUCTION: Status Epilepticus (SE) can occur in patients without a previous epilepsy diagnosis, a condition identified as "new-onset status epilepticus" (NOSE). Treatment with benzodiazepine may fail in NOSE termination, requiring anti-seizure medication (ASM) employment. The term "established NOSE" (eNOSE) is generally employed in this context. This study aims to describe the main clinical characteristics of a large sample of patients suffering from eNOSE, compare the ASM efficacy, and explore the risk factors associated with ASM treatment unresponsiveness and eNOSE-associated mortality. METHODS: Adult patients diagnosed with eNOSE were retrospectively selected between January 2016 and December 2022. We reviewed demographics, clinical data, diagnostic work-up, and treatment. We considered the last ASM introduced before the eNOSE termination as effective. RESULTS: 123 patients were included (age: 67.9 ± 17.3). eNOSE acute etiology was mostly reported. In the overall cohort, phenytoin showed the highest response rate (p = 0.01). In the pairwise comparisons, valproate was superior to levetiracetam (p = 0.02) but not to lacosamide (p = 0.50). Phenytoin had a significantly higher resolution rate than levetiracetam (p = 0.001) but not lacosamide (p = 0.14). Thirty patients were refractory to ASM treatment. No predictors of refractoriness were identified. Thirty-nine patients died. Age and GCS were identified as eNOSE-related mortality risk factors. CONCLUSION: eNOSE frequently has an acute etiology with several associated syndromes. Phenytoin is more effective in managing eNOSE, even though lacosamide, valproate, and levetiracetam can represent further therapeutic options. Age and GCS are the main risk factors for eNOSE-associated mortality.

Resolving Phenotypic Variability in Mitochondrial Diseases: Preliminary Findings of a Proteomic Approach.

The introduction of new sequencing approaches into clinical practice has radically changed the diagnostic approach to mitochondrial diseases, significantly improving the molecular definition rate in this group of neurogenetic disorders. At the same time, there have been no equal successes in the area of in-depth understanding of disease mechanisms and few innovative therapeutic approaches have been proposed recently. In this regard, the identification of the molecular basis of phenotypic variability in primary mitochondrial disorders represents a key aspect for deciphering disease mechanisms with important therapeutic implications. In this study, we present data from proteomic investigations in two subjects affected by mitochondrial disease characterized by a different clinical severity and associated with the same variant in the TWNK gene, encoding the mitochondrial DNA and RNA helicase with a specific role in the mtDNA replisome. Heterozygous pathogenic variants in this gene are associated with progressive external ophthalmoplegia and ptosis, usually with adult onset. The overall results suggest an imbalance in glucose metabolism and ROS production/regulation, with possible consequences on the phenotypic manifestations of the enrolled subjects. Although the data will need to be validated in a large cohort, proteomic investigations have proven to be a valid approach for a deep understanding of these neurometabolic disorders.

Mitochondrial Biomarkers in the Omics Era: A Clinical-Pathophysiological Perspective.

Mitochondrial diseases (MDs) affect 4300 individuals, with different ages of presentation and manifestation in any organ. How defects in mitochondria can cause such a diverse range of human diseases remains poorly understood. In recent years, several published research articles regarding the metabolic and protein profiles of these neurogenetic disorders have helped shed light on the pathogenetic mechanisms. By investigating different pathways in MDs, often with the aim of identifying disease biomarkers, it is possible to identify molecular processes underlying the disease. In this perspective, omics technologies such as proteomics and metabolomics considered in this review, can support unresolved mitochondrial questions, helping to improve outcomes for patients.

Distribution of Exonic Variants in Glycogen Synthesis and Catabolism Genes in Late Onset Pompe Disease (LOPD).

Pompe disease (PD) is a monogenic autosomal recessive disorder caused by biallelic pathogenic variants of the GAA gene encoding lysosomal alpha-glucosidase; its loss causes glycogen storage in lysosomes, mainly in the muscular tissue. The genotype-phenotype correlation has been extensively discussed, and caution is recommended when interpreting the clinical significance of any mutation in a single patient. As there is no evidence that environmental factors can modulate the phenotype, the observed clinical variability in PD suggests that genetic variants other than pathogenic GAA mutations influence the mechanisms of muscle damage/repair and the overall clinical picture. Genes encoding proteins involved in glycogen synthesis and catabolism may represent excellent candidates as phenotypic modifiers of PD. The genes analyzed for glycogen synthesis included UGP2, glycogenin (GYG1-muscle, GYG2, and other tissues), glycogen synthase (GYS1-muscle and GYS2-liver), GBE1, EPM2A, NHLRC1, GSK3A, and GSK3B. The only enzyme involved in glycogen catabolism in lysosomes is α-glucosidase, which is encoded by GAA, while two cytoplasmic enzymes, phosphorylase (PYGB-brain, PGL-liver, and PYGM-muscle) and glycogen debranching (AGL) are needed to obtain glucose 1-phosphate or free glucose. Here, we report the potentially relevant variants in genes related to glycogen synthesis and catabolism, identified by whole exome sequencing in a group of 30 patients with late-onset Pompe disease (LOPD). In our exploratory analysis, we observed a reduced number of variants in the genes expressed in muscles versus the genes expressed in other tissues, but we did not find a single variant that strongly affected the phenotype. From our work, it also appears that the current clinical scores used in LOPD do not describe muscle impairment with enough qualitative/quantitative details to correlate it with genes that, even with a slightly reduced function due to genetic variants, impact the phenotype.

Factors associated with the severity of COVID-19 outcomes in people with neuromuscular diseases: Data from the International Neuromuscular COVID-19 Registry.

BACKGROUND AND PURPOSE: Clinical outcome information on patients with neuromuscular diseases (NMDs) who have been infected with SARS-CoV-2 is limited. The aim of this study was to determine factors associated with the severity of COVID-19 outcomes in people with NMDs. METHODS: Cases of NMD, of any age, and confirmed/presumptive COVID-19, submitted to the International Neuromuscular COVID-19 Registry up to 31 December 2021, were included. A mutually exclusive ordinal COVID-19 severity scale was defined as follows: (1) no hospitalization; (2) hospitalization without oxygenation; (3) hospitalization with ventilation/oxygenation; and (4) death. Multivariable ordinal logistic regression analyses were used to estimate odds ratios (ORs) for severe outcome, adjusting for age, sex, race/ethnicity, NMD, comorbidities, baseline functional status (modified Rankin scale [mRS]), use of immunosuppressive/immunomodulatory medication, and pandemic calendar period. RESULTS: Of 315 patients from 13 countries (mean age 50.3 [±17.7] years, 154 [48.9%] female), 175 (55.5%) were not hospitalized, 27 (8.6%) were hospitalized without supplemental oxygen, 91 (28.9%) were hospitalized with ventilation/supplemental oxygen, and 22 (7%) died. Higher odds of severe COVID-19 outcomes were observed for: age ≥50 years (50-64 years: OR 2.4, 95% confidence interval [CI] 1.33-4.31; >64 years: OR 4.16, 95% CI 2.12-8.15; both vs. <50 years); non-White race/ethnicity (OR 1.81, 95% CI 1.07-3.06; vs. White); mRS moderately severe/severe disability (OR 3.02, 95% CI 1.6-5.69; vs. no/slight/moderate disability); history of respiratory dysfunction (OR 3.16, 95% CI 1.79-5.58); obesity (OR 2.24, 95% CI 1.18-4.25); ≥3 comorbidities (OR 3.2, 95% CI 1.76-5.83; vs. ≤2; if comorbidity count used instead of specific comorbidities); glucocorticoid treatment (OR 2.33, 95% CI 1.14-4.78); and Guillain-Barré syndrome (OR 3.1, 95% CI 1.35-7.13; vs. mitochondrial disease). CONCLUSIONS: Among people with NMDs, there is a differential risk of COVID-19 outcomes according to demographic and clinical characteristics. These findings could be used to develop tailored management strategies and evidence-based recommendations for NMD patients.

Treatment of benzodiazepine-refractory status epilepticus: A retrospective, cohort study.

INTRODUCTION: Status epilepticus (SE) is a frequent neurological emergency, derived from the failure of mechanisms responsible for seizure termination. The present study aims to compare the efficacy of the most common antiseizure medications (ASMs) employed for the treatment of benzodiazepine-refractory SE. METHODS: We performed a retrospective cohort study of all SE episodes treated in our hospital between January 2016 and December 2020. Inclusion criteria were: age ≥ 18 years; a diagnosis of status epilepticus. Exclusion criteria were: status epilepticus resolved by initial therapy with benzodiazepines; impossibility to retrieve medical records. We considered as effective the ASM that was the last drug introduced or increased in dose before termination of SE and without changes in the co-medication. RESULTS: A total of 244 episodes in 219 patients were included in the study. The mean age of the final study cohort was 63.6 ± 19.2, with 108 (49%) men. In the total cohort, phenytoin (PHT) showed the highest response rate (57.6%), followed by lacosamide (LCM) (40.7%) and valproate (VPA) (39.8%). The comparative efficacy among the different drugs was significantly different (p < 0.001). In the pairwise comparisons, VPA was superior to levetiracetam (LEV) (response rate: 39.75% vs 24.71%; p = 0.004), but not to LCM. Phenytoin had a significantly higher resolution rate compared to VPA (response rate: 57.63% vs 39.75%; p = 0.02) and LEV (response rate: 57.63% vs 24.71; p < 0.001). The clinical predictors of anaesthetics administration were a disorder of consciousness upon clinical presentation, previous diagnosis of epilepsy, and younger age. CONCLUSION: In our cohort of SE, PHT showed higher effectiveness in terminating established SE, as well as refractory SE in the subgroup of patients treated with anaesthetics.

European Academy of Neurology guidance for developing and reporting clinical practice guidelines on rare neurological diseases.

BACKGROUND AND PURPOSE: Rare diseases affect up to 29 million people in the European Union, and almost 50% of them affect the nervous system or muscles. Delays in diagnosis and treatment onset and insufficient treatment choices are common. Clinical practice guidelines (CPGs) may improve the diagnosis and treatment of patients and optimize care pathways, delivering the best scientific evidence to all clinicians treating these patients. Recommendations are set for developing and reporting high-quality CPGs on rare neurological diseases (RNDs) within the European Academy of Neurology (EAN), through a consensus procedure. METHODS: A group of 27 experts generated an initial list of items that were evaluated through a two-step Delphi consensus procedure and a face-to-face meeting. The final list of items was reviewed by an external review group of 58 members. RESULTS: The consensus procedure yielded 63 final items. Items are listed according to the domains of the AGREE instruments and concern scope and purpose, stakeholder involvement, rigour of development, and applicability. Additional items consider reporting and ethical issues. Recommendations are supported by practical examples derived from published guidelines and are presented in two tables: (1) items specific to RND CPGs, and general guideline items of special importance for RNDs, or often neglected; (2) items for guideline development within the EAN. CONCLUSIONS: This guidance aims to provide solutions to the issues specific to RNDs. This consensus document, produced by many experts in various fields, is considered to serve as a starting point for further harmonization and for increasing the quality of CPGs in the field of RNDs.

Preventive migraine treatment in mitochondrial diseases: a case report of erenumab efficacy and literature review.

Migraine is a common condition in mitochondrial diseases, with a higher prevalence than in the general population. Although several clinical studies support the hypothesis that mitochondrial dysfunction plays a central role in the pathophysiology of migraine, currently there are few data in the literature regarding the efficacy and safety of drugs for the treatment and prophylaxis for this condition in patients with primary mitochondrial disorders. We report a 37-year-old woman affected by mitochondrial disease with progressive external ophthalmoplegia phenotype (PEO) associated with POLG mutation effectively treated with erenumab, in the absence of side effects. Monoclonal antibodies against the calcitonin gene-related peptide (CGRP) or against its receptor are innovative and specific therapies for migraine prophylaxis. This class of drugs is particularly suitable for subjects, such as those suffering from genetically determined mitochondrial dysfunction, in which pharmacological management can represent a challenge due to the nature of these neurogenetic disorders and/or the frequently associated comorbidities.

Neurofilament light chain as a disease severity biomarker in ATTRv: data from a single-centre experience.

BACKGROUND: Hereditary transthyretin amyloidosis (ATTRv) is a treatable multisystem disorder with prevalent peripheral nervous system impairment. Besides neurophysiological measures, there are few markers to monitor disease progression. Neurofilament light chain (NfL) has recently been considered a sensitive biomarker for neuroaxonal damage in this setting. OBJECTIVE: To evaluate NfL levels in a cohort of ATTRv patients and pre-symptomatic carriers and correlate the serum concentrations with other markers of disease severity. METHODS: We analysed NfL serum from 17 ATTRv patients or carriers and 26 controls. An exhaustive clinical and instrumental evaluation was performed in all patients. RESULTS: NfL levels were significantly higher in ATTRv cases when compared with controls. A significant correlation was found between NfL values and NIS scale, Sudoscan values from feet, interventricular septum thickness, and Quality of Life-Diabetic Neuropathy (Norfolk QoL-DN) questionnaire. CONCLUSION: We confirm that NfL is a reliable and promising biomarker to evaluate the ATTRv severity and monitor its progression.

Impact of COVID-19 vaccine on epilepsy in adult subjects: an Italian multicentric experience.

OBJECTIVES: To investigate the safety and tolerability of COVID-19 vaccines in people with epilepsy (PwE). METHODS: In this multicentric observational cohort study, we recruited adult patients (age > 18 years old) with epilepsy who attended the Outpatient Epilepsy Clinic from 1st July to 30th October 2021. We administered to the patients a structured questionnaire and interview on demographic and epilepsy characteristics, current treatment, previous SARS-CoV-2 infection, vaccine characteristics, post-vaccine seizure relapse, other side effect, variation of sleep habits, caffeine, or alcohol intake. Seizure frequency worsening was defined as a ratio between mean monthly frequency post-vaccination and mean monthly frequency pre-vaccination superior to 1. Patients were categorized in two groups: patients with seizure frequency worsening (WORSE) and patients with seizure stability (STABLE). RESULTS: A total of 358 people participated with a mean age of 47.46 ± 19.04. Focal seizure (79.1%), generalized epilepsy (20.4%), and unknown types of epilepsy (0.5%) were detected among participants. In total, 31 (8.7%) people expressed that they were not willing to receive a COVID-19 vaccine; 302 patients (92.35%) did not experience an increase in the seizure frequency (STABLE-group) whereas 25 patients (7.65%) had a seizure worsening (WORSE-group). Post-vaccine seizures occurred mainly in the 7 days following the administration of the vaccine. Patients in the WORSE-group were treated with a mean higher number of anti-seizure medication (ASMs) (p = 0.003) and had a higher pre-vaccine seizure frequency (p = 0.009) compared with patients in the STABLE-group. Drug-resistant epilepsy was also associated with seizure worsening (p = 0.01). One-year pre-vaccination seizure frequency pattern demonstrated that patients in the WORSE-group had a higher frequency pattern (p < 0.001). Multivariate analysis of the vaccinated group showed that only the seizure frequency pattern (confidence interval [CI] = 1.257-2.028; p < 0.001) was significantly associated with seizure worsening. CONCLUSION: In our cohort of vaccinated PwE, only a little percentage had a transient short-term increase of seizure frequency. The present study demonstrates that COVID-19 vaccines have a good safety and tolerability profile in the short term in PwE.

Vitamin D in Neurological Diseases.

Vitamin D may have multiple effects on the nervous system and its deficiency can represent a possible risk factor for the development of many neurological diseases. Recent studies are also trying to clarify the different effects of vitamin D supplementation over the course of progressive neurological diseases. In this narrative review, we summarise vitamin D chemistry, metabolism, mechanisms of action, and the recommended daily intake. The role of vitamin D on gene transcription and the immune response is also reviewed. Finally, we discuss the scientific evidence that links low 25-hydroxyvitamin D concentrations to the onset and progression of severe neurological diseases, such as multiple sclerosis, Parkinson's disease, Alzheimer's disease, migraine, diabetic neuropathy and amyotrophic lateral sclerosis. Completed and ongoing clinical trials on vitamin D supplementation in neurological diseases are listed.

Personalized Medicine in Mitochondrial Health and Disease: Molecular Basis of Therapeutic Approaches Based on Nutritional Supplements and Their Analogs.

Mitochondrial diseases (MDs) may result from mutations affecting nuclear or mitochondrial genes, encoding mitochondrial proteins, or non-protein-coding mitochondrial RNA. Despite the great variability of affected genes, in the most severe cases, a neuromuscular and neurodegenerative phenotype is observed, and no specific therapy exists for a complete recovery from the disease. The most used treatments are symptomatic and based on the administration of antioxidant cocktails combined with antiepileptic/antipsychotic drugs and supportive therapy for multiorgan involvement. Nevertheless, the real utility of antioxidant cocktail treatments for patients affected by MDs still needs to be scientifically demonstrated. Unfortunately, clinical trials for antioxidant therapies using α-tocopherol, ascorbate, glutathione, riboflavin, niacin, acetyl-carnitine and coenzyme Q have met a limited success. Indeed, it would be expected that the employed antioxidants can only be effective if they are able to target the specific mechanism, i.e., involving the central and peripheral nervous system, responsible for the clinical manifestations of the disease. Noteworthily, very often the phenotypes characterizing MD patients are associated with mutations in proteins whose function does not depend on specific cofactors. Conversely, the administration of the antioxidant cocktails might determine the suppression of endogenous oxidants resulting in deleterious effects on cell viability and/or toxicity for patients. In order to avoid toxicity effects and before administering the antioxidant therapy, it might be useful to ascertain the blood serum levels of antioxidants and cofactors to be administered in MD patients. It would be also worthwhile to check the localization of mutations affecting proteins whose function should depend (less or more directly) on the cofactors to be administered, for estimating the real need and predicting the success of the proposed cofactor/antioxidant-based therapy.

Sleep Disorders in Mitochondrial Diseases.

PURPOSE OF REVIEW: We aim to summarize the sleep disorders reported in patients affected by primary mitochondrial dysfunctions and describe the association with their clinical and molecular characteristics. RECENT FINDINGS: Sleep complaints are prevalent in mitochondrial disorders. Sleep-disordered breathing is the main sleep disorder reported in mitochondrial diseases. OSA and CSA are, respectively, more frequently associated with patients characterized by the prevalent involvement of the skeletal muscle and the predominant involvement of the central nervous system. Other sleep disorders, such as restless legs syndrome, have been rarely described. Sleep disorders are frequently associated with primary mitochondrial disorders, and the clinical phenotypes affect the type of sleep disturbance associated with the mitochondrial dysfunction. A polysomnographic study should be performed in every subject with this neurogenetic disorder both at diagnosis and during follow-up for the numerous adverse clinical outcomes associated with sleep disorders and the frailty of mitochondrial patients.

Expanding the spectrum of congenital myopathies: prenatal onset with extreme hyperextension of the neck.

We describe the case of a male newborn presenting with a prenatal diagnosis of persistent hyperextension of the fetal neck and severe hypotonia and respiratory insufficiency at birth. Facial weakness, increased serum creatine kinase levels, and abnormal feeding, together with other signs, such as severe contractures, also classically associated with congenital myopathies prompted to perform a muscle biopsy showing internal rods suggestive of a possible nemaline myopathy. These findings suggest that a careful neurological examination should be performed in infants with persistent hyperextension of the fetal neck to exclude weakness and a possible underlying muscle disorder.

Novel KCND3 Variant Underlying Nonprogressive Congenital Ataxia or SCA19/22 Disrupt KV4.3 Protein Expression and K+ Currents with Variable Effects on Channel Properties.

KCND3 encodes the voltage-gated potassium channel KV4.3 that is highly expressed in the cerebellum, where it regulates dendritic excitability and calcium influx. Loss-of-function KV4.3 mutations have been associated with dominant spinocerebellar ataxia (SCA19/22). By targeted NGS sequencing, we identified two novel KCND3 missense variants of the KV4.3 channel: p.S347W identified in a patient with adult-onset pure cerebellar syndrome and p.W359G detected in a child with congenital nonprogressive ataxia. Neuroimaging showed mild cerebellar atrophy in both patients. We performed a two-electrode voltage-clamp recording of KV4.3 currents in Xenopus oocytes: both the p.G345V (previously reported in a SCA19/22 family) and p.S347W mutants exhibited reduced peak currents by 50%, while no K+ current was detectable for the p.W359G mutant. We assessed the effect of the mutations on channel gating by measuring steady-state voltage-dependent activation and inactivation properties: no significant alterations were detected in p.G345V and p.S347W disease-associated variants, compared to controls. KV4.3 expression studies in HEK293T cells showed 53% (p.G345V), 45% (p.S347W) and 75% (p.W359G) reductions in mutant protein levels compared with the wildtype. The present study broadens the spectrum of the known phenotypes and identifies additional variants for KCND3-related disorders, outlining the importance of SCA gene screening in early-onset and congenital ataxia.

CACNA1A-p.Thr501Met mutation associated with familial hemiplegic migraine: a family report.

BACKGROUND AND AIMS: Hemiplegic migraine (HM) is a rare form of migraine characterized by the presence of a motor and other types of aura. HM can be sporadic or familial. Familial hemiplegic migraine (FHM) is an autosomal dominant disorder, classified into 3 subtypes, based on the gene involved (CACNA1A in FHM1, ATP1A2 in FHM2 and SCN1A in FHM3). The clinical presentation is highly heterogeneous and some attacks may be severe. We report the clinical characteristics and genetic analysis of 12 patients belonging to a family with CACNA1A-p.Thr501Met gene mutation. METHODS: We screened for mutations in CACNA1A gene 15 patients belonging to the same family. The exonic sequences of CACNA1A were analyzed using a Tru-seq® Custom Amplicon (TSCA) (Illumina Inc., San Diego, CA) targeted capture and paired end library kit. Sanger sequencing was used to confirm CACNA1A variants and segregation analysis. RESULTS: CACNA1A-p.Thr501Met mutation was found in 12 of the 15 patients screened, which was compatible with the diagnosis of FHM1. Attacks of hemiplegic migraine were reported by 10 of the 12 subjects (83.33%). Only one subject developed persistent mild cerebellar symptoms and none of the subjects developed cerebellar atrophy. DISCUSSION: The variant p.Thr501Met was described previously in association with episodic ataxia and rarely with FHM related to cerebellar symptoms. FHM1 has a broad clinical spectrum and about half of the families have cerebellar involvement. In our study, only one patient developed persistent cerebellar deficits. These data suggest that CACNA1A-p.Thr501Met mutation can occur prevalently as hemiplegic migraine.