Search

Objective/background Lemborexant is a dual orexin receptor antagonist approved in the United States, Japan, and Canada for the treatment of insomnia in adults. We report effectiveness and safety outcomes in subjects with insomnia who received up to twelve months of continuous lemborexant treatment in Study E2006-G000-303 (Study 303; SUNRISE-2). Patients/methods Study 303 was a twelve-month, global, multicenter, randomized, double-blind, parallel-group, Phase 3 study divided into two treatment periods. In Treatment Period 1 (first six months), subjects (n = 949, Full Analysis Set) were randomized to daily placebo, lemborexant 5 mg (LEM5) or lemborexant 10 mg (LEM10). In Treatment Period 2 (second six months), placebo subjects were rerandomized to LEM5 or LEM10, and subjects randomized to lemborexant continued their assigned treatment (LEM5, n = 251; LEM10, n = 226). Sleep onset and sleep maintenance endpoints were analyzed from daily electronic sleep diary data. Treatment-emergent adverse events (TEAEs) were monitored. Results For all sleep parameters, the significant benefits observed with LEM5 and LEM10 versus placebo over six months were maintained at twelve months in subjects who received twelve continuous months of treatment. There was no evidence of rebound insomnia or withdrawal in either lemborexant group following treatment discontinuation. Over twelve months of lemborexant treatment, most TEAEs were mild/moderate; the most common TEAEs were nasopharyngitis, somnolence and headache. Conclusions LEM5 and LEM10 had significant benefit on sleep onset and sleep maintenance compared with placebo, and importantly, lemborexant effectiveness persisted at twelve months, suggesting that lemborexant may provide long-term benefits for subjects with insomnia. Clinical trial registration ClinicalTrials.gov , NCT02952820; ClinicalTrialsRegister.eu, EudraCT Number 2015-001463-39.

Background and Objectives Mutations in the ganglioside-induced differentiation-associated protein 1 (GDAP1) gene cause autosomal dominant or autosomal recessive forms of Charcot-Marie-Tooth disease (CMT). Our aim was to study the clinical phenotype of patients with CMT caused by heterozygous p.His123Arg in GDAP1. Methods Twenty-three Finnish patients were recruited from a population-based cohort and through family investigation. Each patient was examined clinically and electrophysiologically. The Neuropathy Symptom Score and the Neuropathy Disability Score (NDS) were used in clinical evaluation. Results The median age at onset of symptoms was 17 years among patients with p.His123Arg in GDAP1. Motor symptoms were markedly more common than sensory symptoms at onset. All patients had distal weakness in lower extremities, and 17 (74%) patients had proximal weakness. Muscle atrophy and pes cavus were also common. Nineteen (82%) patients had sensory symptoms such as numbness or pain. The disease progressed with age, and the NDS increased 8.5 points per decade. Electrodiagnostic testing revealed length-dependent, sensory and motor axonal polyneuropathy. EDx findings were asymmetrical in 14 patients. Genealogic study of the families suggested a founder effect. Discussion We found that CMT in patients with p.His123Arg in GDAP1 is relatively mild and slow in progression.

Introduction: The Unified Dyskinesia Rating Scale (UDysRS) was developed to provide a comprehensive rating tool of dyskinesia in Parkinson’s disease (PD). Because dyskinesia therapy trials involve multicenter studies, having a scale that is validated in multiple non-English languages is pivotal to international efforts to treat dyskinesia. The aim of the present study was to organize and perform an independent validation of the UDysRS Finnish version. Methods: The UDysRS was translated into Finnish and then back-translated into English using 2 independent teams. Cognitive pretesting was conducted on the Finnish version and required modifications to the structure or wording of the translation. The final Finnish version was administered to 250 PD patients whose native language is Finnish. The data were analyzed to assess the confirmatory factor structure to the Spanish UDysRS (the reference standard). Secondary analyses included an exploratory factor analysis (EFA), independent of the reference standard. Results: The comparative fit index (CFI), in comparison with the reference standard factor structure, was 0.963 for Finnish. In the EFA, where variability from sample to sample is expected, isolated item differences of factor structure were found between the Finnish and Reference Standard versions of the UDysRS. These subtle differences may relate to differences in sample composition or variations in disease status. Conclusion: The overall factor structure of the Finnish version was consistent with that of the reference standard, and it can be designated as the official version of the UDysRS for Finnish speaking populations.

Background The FOCUS study evaluated the efficacy of migraine preventive medications across different countries within the same patient population, particularly for patients with difficult-to-treat migraine. These prespecified subgroup analyses evaluated efficacy by country in the FOCUS study of fremanezumab in adults with episodic migraine or chronic migraine and documented inadequate response to 2 to 4 migraine preventive medication classes. Methods Overall, 838 participants were enrolled in the FOCUS study, a randomized, double-blind, placebo-controlled, parallel-group, phase 3b study performed at 104 sites. For 12 weeks of double-blind treatment, patients were randomized (1:1:1) to quarterly fremanezumab, monthly fremanezumab, or matched placebo. The primary efficacy endpoint was the mean change from baseline in monthly average migraine days over 12 weeks of double-blind treatment, evaluated by country in these subgroup analyses. Results Of 14 countries contributing data, the Czech Republic (n = 188/838; 22%), the United States (n = 120/838; 14%), and Finland (n = 85/838; 10%) enrolled the most patients. Changes from baseline in monthly average migraine days over 12 weeks were significantly greater with fremanezumab versus placebo for patients in these countries: Czech Republic (least-squares mean difference versus placebo [95% confidence interval]: quarterly fremanezumab, − 1.9 [− 3.25, − 0.47]; P = 0.009; monthly fremanezumab, − 3.0 [− 4.39, − 1.59]; P P P P = 0.014; monthly fremanezumab, − 3.9 [− 6.27, − 1.44]; P = 0.002). Results were comparable for the remaining 9 countries, with the least-squares mean difference versus placebo ranging from – 5.6 to – 2.4 with quarterly fremanezumab and from − 5.3 to − 1.5 with monthly fremanezumab. Incidences of serious adverse events and adverse events leading to discontinuation were low and comparable across countries and treatment groups. Conclusions Monthly and quarterly fremanezumab significantly reduced the monthly average number of migraine days versus placebo regardless of country and continent (North America versus Europe) in migraine patients with documented inadequate response to 2 to 4 migraine preventive medication classes. Trial registration ClinicalTrials.gov Identifier: NCT03308968.

Study Objectives To assess long-term efficacy and safety of lemborexant (LEM), a novel dual orexin receptor antagonist, versus placebo in adults with insomnia disorder. Methods This was a 12-month, global, multicenter, randomized, double-blind, parallel-group phase 3 study comprising a 6-month placebo-controlled period (reported here) followed by a 6-month active-treatment-only period (reported separately). A total of 949 participants with insomnia (age ≥18 years) were randomized, received treatment with an oral dose of placebo or LEM (5 mg [LEM5] or 10 mg [LEM10]) and were analyzed. Sleep onset and sleep maintenance endpoints were analyzed from daily electronic sleep diary data. Treatment-emergent adverse events (TEAEs) were monitored throughout the study. Results Decreases from baseline in patient-reported (subjective) sleep onset latency and subjective wake after sleep onset, and increases from baseline in subjective sleep efficiency, were significantly greater with LEM5 and LEM10 versus placebo. Significant benefits over placebo were observed at the end of month 6, and at most time points assessed over the 6-month period, indicating long-term sustained efficacy of LEM. A significantly greater percentage of sleep onset responders and sleep maintenance responders were observed with LEM treatment versus placebo. Participants treated with LEM reported a significant improvement in quality of sleep after 6 months versus placebo. The majority of TEAEs were mild or moderate. There was a low rate of serious TEAEs and no deaths. Conclusions LEM5 and LEM10 provided significant benefit on sleep onset and sleep maintenance in individuals with insomnia disorder versus placebo, and was well tolerated. Clinical trial registration ClinicalTrials.gov, NCT02952820; ClinicalTrialsRegister.eu, EudraCT Number 2015-001463-39

Objective Previous studies have suggested that heterozygous variants p.Q1236H and p.E1143G in mitochondrial DNA polymerase gamma (POLG1) increase the risk for liver injury for patients on valproate (VPA) therapy. We assessed the prevalence of these common variants and seven other pathogenic mutations in POLG1 and determined the occurrence of VPA-induced hepatotoxicity (VHT) or pancreatic toxicity in a cohort of patients with epilepsy. Methods Patients with epilepsy (N = 367) were retrospectively identified from medical record files and screened for mutations in POLG1. Patients who had received VPA monotherapy and carried either of the two variants, p.Q1236H or p.E1143G, without other pathogenic mutations in POLG1 (n = 33, variant group) and patients without these variants (n = 28, nonvariant group) were included in the study. Clinical data on epilepsy, characteristics of VPA treatment, risk factors for VHT, laboratory data on liver and pancreas functions, and adverse effects were collected. Results A total of 122 patients had either the POLG1 p.Q1236H (n = 99) or p.E1143G (n = 24) variant in the heterozygous or homozygous state. Transient liver dysfunction was identified in three (n = 33, 9.1%) variant group patients and in one (n = 28, 3.6%) nonvariant group patient (P = 0.62). Mild to moderate elevations in liver enzymes were encountered in both groups. Furthermore, two patients on VPA polytherapy developed acute pancreatitis, and two pediatric patients with heterozygous p.Q1236H variants and mutations in IQSEC2 and GLDC, respectively, had elevated levels of VPA metabolites in urine, elevated plasma glycine, and/or increased acylglycine excretion. Significance POLG1 p.Q1236H and p.E1143G variants could not be identified as statistically significant risk factors for VHT or pancreatic toxicity. We suggest that VPA treatment could be suitable for patients who harbor these common variants in the absence of other pathogenic mutations in POLG1.

Background and ObjectivesMutations in the ganglioside-induced differentiation-associated protein 1 (GDAP1) gene cause autosomal dominant or autosomal recessive forms of Charcot-Marie-Tooth disease (CMT). Our aim was to study the clinical phenotype of patients with CMT caused by heterozygous p.His123Arg inGDAP1.MethodsTwenty-three Finnish patients were recruited from a population-based cohort and through family investigation. Each patient was examined clinically and electrophysiologically. The Neuropathy Symptom Score and the Neuropathy Disability Score (NDS) were used in clinical evaluation.ResultsThe median age at onset of symptoms was 17 years among patients with p.His123Arg inGDAP1. Motor symptoms were markedly more common than sensory symptoms at onset. All patients had distal weakness in lower extremities, and 17 (74%) patients had proximal weakness. Muscle atrophy and pes cavus were also common. Nineteen (82%) patients had sensory symptoms such as numbness or pain. The disease progressed with age, and the NDS increased 8.5 points per decade. Electrodiagnostic testing revealed length-dependent, sensory and motor axonal polyneuropathy. EDx findings were asymmetrical in 14 patients. Genealogic study of the families suggested a founder effect.DiscussionWe found that CMT in patients with p.His123Arg inGDAP1is relatively mild and slow in progression.

Study Objective(s):This study examined the effects of lemborexant (LEM) compared with placebo (PBO) on subject-reported insomnia disease severity, assessed by the Insomnia Severity Index (ISI), and fatigue, assessed by the Fatigue Severity Score (FSS), from the 6-month PBO-controlled period of SUNRISE-2.Method:SUNRISE-2 (NCT02952820; E2006-G000-303) was a 12-month randomized, double-blind, PBO-controlled (first 6-months) Phase 3 study. After an ~2-week PBO run-in, subjects were randomized to PBO, LEM 5mg (LEM5) or LEM 10mg (LEM10) for 6 months. The ISI and the FSS were administered at baseline [BL] and at the end of Months 1, 3, and 6. The ISI daytime functioning score (DFS), based on the ISI items that assess the impact of insomnia symptoms specific to daily functioning (items 4-7), was also evaluated. Mean changes from BL in ISI total score (ISI TS), ISI DFS, and FSS total score (FSS TS) were analyzed using a mixed-effect model repeated measurement analysis, adjusted for relevant factors and BL score (ISI TS, ISI DFS, or FSS TS) as a covariate.Results:949 subjects (PBO, n=318; LEM5, n=316; LEM10, n=315) were included in the full analysis set. Median age was 55y (range 18-88y). Mean ISI TS at BL for PBO, LEM5, and LEM10 was 19.0, 19.6 and 19.1, respectively. While mean ISI TS decreased (improved) from BL for all groups, decreases were significantly larger for both LEM5 and LEM10 vs PBO at Month 1 (least squares mean treatment difference [LSM TD]: LEM5, −1.5 [P=0.001]; LEM10, −1.9 [PMean FSS TS at BL was 35.2, 37.4, and 36.0 for PBO, LEM5, and LEM10, respectively. Mean FSS TS decreased (improved) from BL in all groups at the end of Month 1 (decreases were larger and significant for LEM10 vs PBO [LSM TD: –2.0 (P=0.026)]), and Month 3 (decreases were larger and significant for LEM5 [LSM TD: –2.2 (P=0.021)] and LEM10 [LSM TD: –3.0; (P=0.001)] vs PBO). At Month 6, mean FSS TS remained improved from BL in all treatment groups (PBO, –6.3; LEM5, –10.1; and LEM10, –8.9). These decreases were larger and significant for LEM5 (LSM TD: –2.5 [P=0.013]) and LEM10 (LSM TD: –2.6 [P=0.013]) vs PBO. LEM was well tolerated with most adverse events mild to moderate in severity.Conclusions:In SUNRISE-2, LEM5 and LEM10 significantly reduced subject-reported disease severity and fatigue vs PBO after 6 months of treatment. Reduced severity in insomnia symptoms with LEM5 and LEM10 also translated to improved daytime functioning.Funding Acknowledgements:Supported by Eisai Inc.

INTRODUCTION: We aimed to explore the value of genetic screening for Fabry disease (FD) and hereditary ATTR amyloidosis in patients with idiopathic small fiber neuropathy (SFN) or mixed neuropathy in a clinical setting.METHODS: This was a Nordic multicenter study with 9 participating centers. Patients with idiopathic SFN or mixed neuropathy were included. Genetic sequencing of the TTR and GLA genes was performed.RESULTS: 172 patients were enrolled. Genetic screening was performed in 155 patients. No pathogenic mutations in the TTR gene were found. A single patient had a possible pathogenic variant, R118C, in the GLA gene, but the clinical investigation showed no firm signs of FD.DISCUSSION: Screening for hereditary ATTR amyloidosis and FD in patients with idiopathic SFN or mixed neuropathy without any additional disease-specific symptoms or clinical characteristics in a Nordic population appears to be of little value in a clinical setting. This article is protected by copyright. All rights reserved.

Previous studies have suggested that heterozygous variants p.Q1236H and p.E1143G in mitochondrial DNA polymerase gamma (POLG1) increase the risk for liver injury for patients on valproate (VPA) therapy. We assessed the prevalence of these common variants and seven other pathogenic mutations in POLG1 and determined the occurrence of VPA-induced hepatotoxicity (VHT) or pancreatic toxicity in a cohort of patients with epilepsy.Patients with epilepsy (N = 367) were retrospectively identified from medical record files and screened for mutations in POLG1. Patients who had received VPA monotherapy and carried either of the two variants, p.Q1236H or p.E1143G, without other pathogenic mutations in POLG1 (n = 33, variant group) and patients without these variants (n = 28, nonvariant group) were included in the study. Clinical data on epilepsy, characteristics of VPA treatment, risk factors for VHT, laboratory data on liver and pancreas functions, and adverse effects were collected.A total of 122 patients had either the POLG1 p.Q1236H (n = 99) or p.E1143G (n = 24) variant in the heterozygous or homozygous state. Transient liver dysfunction was identified in three (n = 33, 9.1%) variant group patients and in one (n = 28, 3.6%) nonvariant group patient (P = 0.62). Mild to moderate elevations in liver enzymes were encountered in both groups. Furthermore, two patients on VPA polytherapy developed acute pancreatitis, and two pediatric patients with heterozygous p.Q1236H variants and mutations in IQSEC2 and GLDC, respectively, had elevated levels of VPA metabolites in urine, elevated plasma glycine, and/or increased acylglycine excretion.POLG1 p.Q1236H and p.E1143G variants could not be identified as statistically significant risk factors for VHT or pancreatic toxicity. We suggest that VPA treatment could be suitable for patients who harbor these common variants in the absence of other pathogenic mutations in POLG1.

Background: Charcot-Marie-Tooth (CMT) disease is the most common hereditary neuromuscular disorder with a population prevalence of 9.7-82.3/100,000. In this study, we have estimated the prevalence of CMT and its subtypes in Finland and examined the frequency of molecular etiologies. Methods: A population-based survey included adult patients with peripheral neuropathy from the province of Northern Ostrobothnia, Finland. Secondary causes of peripheral polyneuropathy were excluded and patients with clinical and neurophysiological features pertinent with CMT were included. Molecular diagnostics was carried out when DNA was available. Results: We found 107 subjects with CMT yielding a prevalence 34.6/100,000 in Northern Ostrobothnia. The heterozygous point mutation p.His123Arg in ganglioside induced differentiation associated protein 1 (GDAP1) was found in 31.5% and peripheral myelin protein 22 (PMP22) duplication in 16.9% of the affected. Point mutations in myelin protein zero, mitofusin 2, and gap junction protein beta 1 accounted for 6.7% of the cases. In addition, 18 persons had hereditary neuropathy with liability to pressure palsies and 15 of them carried the PMP22 deletion. Conclusions: The prevalence of CMT in Northern Ostrobothnia, Finland, seems to be slightly higher than those in previous studies in European populations. Founder mutation in the GDAP1 gene accounts for a large part of the genetically defined CMT2 in Finland.

Key Clinical Message Autosomal recessive spastic ataxia of Charlevoix-Saguenay is a rare disorder outside Quebec causing childhood-onset cerebellar ataxia, peripheral neuropathy, and pyramidal tract signs. A Finnish family with milder form of ARSACS was found to harbor three mutations, p.E1100K, p.N1489S, and p.M1359T, in SACS gene. The mutations segregated with the disease.

Background: Mitochondrial cytochrome c oxidase 2, MT-CO2, encodes one of the three subunits, which form the catalytic core of cytochrome c oxidase (COX), complex IV. Mutations in MT-CO2 are rare and the associated phenotypes are variable including nonsyndromic and syndromic forms of mitochondrial diseases. Case presentation: We describe a 30-year-old man with cognitive decline, epilepsy, psychosis, exercise intolerance, sensorineural hearing impairment, retinitis pigmentosa, cataract and lactic acidosis. COX-deficient fibers and ragged red fibers were abundant in the muscle. Sequencing of mitochondrial DNA (mtDNA) revealed a novel frameshift mutation m.8156delG that was predicted to cause altered C-terminal amino acid sequence and to lead to truncation of the COX subunit 2. The deletion was heteroplasmic being present in 26% of the mtDNA in blood, 33% in buccal mucosa and 95% in muscle. Deletion heteroplasmy correlated with COX-deficiency in muscle histochemistry. The mother and the siblings of the proband did not harbor the deletion. Conclusions: The clinical features and muscle histology of the proband suggested a mitochondrial disorder. The m.8156delG deletion is a new addition to the short list of pathogenic mutations in the mtDNA-encoded subunits of COX. This case illustrates the importance of mtDNA sequence analysis in patients with an evident mitochondrial disorder.

We report a case of late-onset predominantly axonal Charcot-Marie-Tooth disease resulting from a novel mutation in the MPZ gene encoding myelin protein zero (P0). Neurological examination, electrophysiological examination and genetic testing were performed on three members of a Finnish family (family A) and one member of a German family (family B). Three other members of the Finnish family were interviewed and genetically tested. Genetic testing was also performed on 95 healthy Finnish controls. Three members in two generations of family A and the member of family B were affected with late-onset axonal more than demyelinating, motor and sensory polyneuropathy. Heterozygous c.316C>T mutation in MPZ leading to p.Arg106Cys in P0 was found in all the affected subjects, but not in the three unaffected members of the Finnish family. None of 95 healthy Finnish controls harbored the mutation. The findings of this study indicate that p.Arg106Cys allele in MPZ causes late-onset predominantly axonal sensory and motor neuropathy.

Mitochondrial mutations impair glucose oxidation and increase glucose uptake in cell cultures and lead to cardiomyopathy in patients. Here we characterize cardiac glucose uptake in 14 patients with the m.3243A G mutation in mitochondrial DNA. The 14 patients with m.3243A G and 13 controls were similar in age, physical activity and body mass index. Ten patients had diabetes. Left ventricular glucose uptake per tissue mass (LVGU) was measured with 2-[(18) F]fluoro-2-deoxyglucose positron emission tomography during euglycemic hyperinsulinemia. Cardiac morphology and function were assessed with magnetic resonance imaging. We found that the LVGU was 25% lower in the patients than that in the controls (P = 0.029). LVGU was inversely correlated with mutation heteroplasmy, glycated haemoglobin and fasting lactate in patients. The seven patients with mutation heteroplasmy ≥ 49% had 44% lower LVGU than the seven patients with heteroplasmy 49%. This difference remained significant after adjustment for concurrent free fatty acid concentration or glycated haemoglobin or glucose uptake in skeletal muscle or all (p 0.048 [All]). Patients with m.3243A G had a lower stroke volume and a higher heart rate than the controls, whereas cardiac output and work were similar. Myocardial glucose uptake is not increased but decreased with a threshold effect pattern in patients with the m.3243A G mutation. The glucose hypometabolism adds to the impaired cardiac energetics and likely contributes to the progression of the mitochondrial cardiomyopathy.

Myopathy is a typical clinical finding among patients with the 3243A>G mutation in mitochondrial DNA (mtDNA), but the variability in such findings has not been properly established. We have previously determined the prevalence of patients with 3243A>G in a defined population in northern Finland and characterized a group of patients who represent a good approximation to a population-based cohort. We report here on examinations performed on patients belonging to this cohort in order to determine the frequency of myopathy and to evaluate the clinical, histological, ultrastructural and single fibre mtDNA variability in muscle involvement. Fifty patients with 3243A>G underwent a thorough structured interview and clinical examination. Muscle histology, ultrastructure and single fibre analysis were examined in a subset of patients. A clinical diagnosis of myopathy was made in 50% of cases [95% confidence interval (CI), 36-64] and abnormalities in muscle histology were found in 72% (95% CI, 55-86). Moderate limb weakness leading to functional impairment was the most common myopathic sign, but mild weakness, ptosis and external ophthalmoplegia could also be found. The presence of intramitochondrial crystals and cytochrome c oxidase (COX)-negative fibres and variation in mitochondrial size and shape were more common in the muscles of the myopathic patients. Longitudinal variations in mutation heteroplasmy were examined in single muscle fibres from two severely affected patients. Although the total variation in mutation heteroplasmy along four ragged red fibres (RRFs) was small, the mutation heteroplasmy in five 10 microm segments was clearly lower (median 68%, range 64-74%) than that in the neighbouring segments. There were also segments with deviant mutation load in histologically normal fibres in one patient. The highest incidence of myopathy was in the fifth decade of life, but, apart from age, no other clinical variables such as gender, muscle heteroplasmy, physical inactivity or diabetes were associated with an increased risk of myopathy. The clinical presentation of myopathy is highly variable in patients with 3243A>G.

Computed tomography provides a sensitive method for investigating skeletal muscle changes in neuromuscular diseases, but this method has not been applied to mitochondrial myopathies. We characterized the pattern of muscle involvement in patients with the 3243A>G mutation in mitochondrial DNA (mtDNA), the common MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes) mutation. Twenty-four patients, age 19–73 years, with 3243A>G were examined. Clinical evaluation included assessment of muscle strength and functional capacity. All the patients underwent muscle computed tomography, and muscle samples from 17 of them were examined for the presence of ragged red fibres and for the 3243A>G heteroplasmy. Venous blood lactate at rest and serum creatine kinase were determined. Clinical myopathy was found in six patients, while nine showed mild muscle weakness and nine had normal muscle function. The upper and lower limbs were equally affected, but the proximal muscles were more severely affected than the distal ones. CT revealed abnormalities in the muscles of 13 patients (54%; 95% confidence interval, 33–76%), including the six with clinical myopathy and seven without clinical myopathy. Myopathic changes were found most frequently in the pelvic muscles, with predominant involvement of the gluteus maximus. These data show that CT reveals frequent abnormal findings in the muscle of patients with the 3243A>G mtDNA mutation.Muscle CT is a useful adjunct to clinical evaluation in these patients.

Parkinsonism has been described in patients with mutations in POLG1 gene. The W748S mutation is one of the most common mutations in this gene and it has been found to be a frequent cause of autosomal recessive ataxia in adults and the Alpers syndrome in children. We found the W748S mutation in a 65-year-old man with a late-onset syndrome consisting of ataxia, parkinsonism, ophthalmoplegia, peripheral neuropathy, and sensorineural hearing loss. Parkinsonism is one of the phenotypic features associated also with the W748S mutation.

SummaryMitochondrial diseases are characterized by considerable clinical variability and are most often caused by mutations in mtDNA. Because of the phenotypic variability, epidemiological studies of the frequency of these disorders have been difficult to perform. We studied the prevalence of the mtDNA mutation at nucleotide 3243 in an adult population of 245,201 individuals. This mutation is the most common molecular etiology of MELAS syndrome (mitochondrial encephalomyopathy, lactic acidosis, and strokelike episodes), one of the clinical entities among the mitochondrial disorders. Patients with diabetes mellitus, sensorineural hearing impairment, epilepsy, occipital brain infarct, ophthalmoplegia, cerebral white-matter disease, basal-ganglia calcifications, hypertrophic cardiomyopathy, or ataxia were ascertained on the basis of defined clinical criteria and family-history data. A total of 615 patients were identified, and 480 samples were examined for the mutation. The mutation was found in 11 pedigrees, and its frequency was calculated to be ⩾16.3/100,000 in the adult population (95% confidence interval 11.3–21.4/100,000). The mutation had arisen in the population at least nine times, as determined by mtDNA haplotyping. Clinical evaluation of the probands revealed a syndrome that most frequently consisted of hearing impairment, cognitive decline, and short stature. The high prevalence of the common MELAS mutation in the adult population suggests that mitochondrial disorders constitute one of the largest diagnostic categories of neurogenetic diseases.

Objective: Several families with characteristic features of hereditary myopathy with early respiratory failure (HMERF) have remained without genetic cause. This international study was initiated to clarify epidemiology and the genetic underlying cause in these families, and to characterise the phenotype in our large cohort. Methods: DNA samples of all currently known families with HMERF without molecular genetic cause were obtained from 12 families in seven different countries. Clinical, histopathological and muscle imaging data were collected and five biopsy samples made available for further immunohistochemical studies. Genotyping, exome sequencing and Sanger sequencing were used to identify and confirm sequence variations. Results: All patients with clinical diagnosis of HMERF were genetically solved by five different titin mutations identified. One mutation has been reported while four are novel, all located exclusively in the FN3 119 domain (A150) of A-band titin. One of the new mutations showed semirecessive inheritance pattern with subclinical myopathy in the heterozygous parents. Typical clinical features were respiratory failure at mid-adulthood in an ambulant patient with very variable degree of muscle weakness. Cytoplasmic bodies were retrospectively observed in all muscle biopsy samples and these were reactive for myofibrillar proteins but not for titin. Conclusions: We report an extensive collection of families with HMERF with five different mutations in exon 343 of TTN, which establishes this exon as the primary target for molecular diagnosis of HMERF. Our relatively large number of new families and mutations directly implies that HMERF is not extremely rare, not restricted to Northern Europe and should be considered in undetermined myogenic respiratory failure.

The syndrome of mitochondrial encephalomyopathy, lactic acidosis, and strokelike episodes (MELAS) may present with symptoms that resemble a stroke. The strokelike episodes most commonly involve the posterior part of the cerebrum. We identified retrospectively 38 patients with an occipital stroke between ages 18 to 45 years during a 19-year period in a hospital serving as the only neurologic center for a specific population. The common MELAS mutation at the base pair 3243 (A3243G) of the mitochondrial DNA (mtDNA) was analyzed in blood samples. We found four patients (10%) with a clinical or molecular diagnosis of a mitochondrial disorder. Two of the patients carried the A3243G mutation, suggesting frequencies of 6% among patients younger than 45 years of age and 14% among patients younger than 30 years for this mutation. Furthermore, we identified two patients with a clinically definite mitochondrial disorder, and sequencing of the 22 transfer RNA genes revealed the mtDNA mutation A12308G in one patient. Clinical evaluation revealed that occipital stroke was part of a more complex syndrome in these four patients. These population-based findings demonstrate that the A3243G mutation in the mtDNA, and mitochondrial disorders are not uncommon among young patients with occipital stroke.

Contains fulltext : 88043.pdf (Publisher’s version ) (Closed access) The autosomal recessive kidney disease nephronophthisis (NPHP) constitutes the most frequent genetic cause of terminal renal failure in the first 3 decades of life. Ten causative genes (NPHP1-NPHP9 and NPHP11), whose products localize to the primary cilia-centrosome complex, support the unifying concept that cystic kidney diseases are "ciliopathies". Using genome-wide homozygosity mapping, we report here what we believe to be a new locus (NPHP-like 1 [NPHPL1]) for an NPHP-like nephropathy. In 2 families with an NPHP-like phenotype, we detected homozygous frameshift and splice-site mutations, respectively, in the X-prolyl aminopeptidase 3 (XPNPEP3) gene. In contrast to all known NPHP proteins, XPNPEP3 localizes to mitochondria of renal cells. However, in vivo analyses also revealed a likely cilia-related function; suppression of zebrafish xpnpep3 phenocopied the developmental phenotypes of ciliopathy morphants, and this effect was rescued by human XPNPEP3 that was devoid of a mitochondrial localization signal. Consistent with a role for XPNPEP3 in ciliary function, several ciliary cystogenic proteins were found to be XPNPEP3 substrates, for which resistance to N-terminal proline cleavage resulted in attenuated protein function in vivo in zebrafish. Our data highlight an emerging link between mitochondria and ciliary dysfunction, and suggest that further understanding the enzymatic activity and substrates of XPNPEP3 will illuminate novel cystogenic pathways.

Characteristic symptoms of acute polyradiculitis are parestesia beginning from the feet and a symmetrically ascending myasthenia. The symptomatology, which may vary from mild asthenia to complete tetraplegia, may be accompanied by asphyxia and symptoms of the autonomic nervous system and cranial nerves. Polyradiculitis is often preceded by an infection. An elevated protein level of the cerebrospinal fluid without cellular reaction is the typical finding, but a specific laboratory test is not available. The clinical course is monophasic and relapses are uncommon. The natural prognosis for recovery is fairly good, but one fifth are left with functional impairment and the disease may even be fatal.

Objective: To follow the clinical course of patients with the mitochondrial DNA mutation 3243A>G for 3 years. Methods: Thirty-three adult patients with the 3243A>G mutation entered a 3-year follow-up study. They were clinically evaluated annually, audiometry was performed, and samples were drawn for the analysis of blood chemistry and mutation heteroplasmy in leukocytes. Holter recording was performed three times during the follow-up and echocardiography, neuropsychological assessment, and quantitative EEG and brain imaging conducted at entry and after 3 years. Results: The incidence of new neurologic events was low during the 3-year follow-up. Sensorineural hearing impairment (SNHI) progressed, left ventricular wall thickness increased, mean α frequency in the occipital and parietal regions decreased, and the severity of disease index (modified Rankin score) progressed significantly. The rate of SNHI progression correlated with mutation heteroplasmy in muscle. The increase in left ventricular wall thickness was seen almost exclusively in diabetic patients. Seven patients died during the follow-up, and they were generally more severely affected than those who survived. Conclusions: Significant changes in the severity of disease, sensorineural hearing impairment, left ventricular hypertrophy, and quantitative EEG were seen in adult patients with 3243A>G during the 3-year follow-up.

We have previously described a patient with cerebral autosomal-dominant arteriopathy with subcortical infarcts and leucoencephalopathy (CADASIL) caused by R133C mutation in NOTCH3 and with a concomitant myopathy caused by a G to A point mutation at base pair 5650 (5650G>A) in the gene encoding tRNA Ala in mitochondrial DNA (mtDNA). In the present study, we have examined the morphology of the cytoskeletal components in fibroblasts and myoblasts of this patient. Immunolabeling revealed that tubulin network was sparse and formed asters in these cells, whereas no changes were found in actin and vimentin networks in comparison to the control cell lines. Furthermore, mitochondria were less abundant and the branches of the mitochondrial network were reduced in number. Muscle histochemical analysis showed ragged red fibres (RRFs) and cytochrome c oxidase (COX)-negative fibres. The mean proportion of mtDNA with 5650G>A was lower in histologically normal muscle fibres than in the COX-negative fibres and in the RRFs. These findings suggest that 5650G>A is a pathogenic mtDNA mutation. However, the changes in tubulin network and mitochondrial distribution in patient fibroblasts and myoblasts cannot solely be explained by this mutation.

Several patients with previously reported titin gene (TTN) mutations causing tibial muscular dystrophy (TMD) have more complex, severe or unusual phenotypes. This study aimed to clarify the molecular cause of these variant phenotypes in proband patients of six European families. Clinical, histopathological and muscle imaging data of patients and family members was reanalyzed and muscle biopsies of the patients were studied by titin Western blotting and RT-PCR. Western blotting showed a more pronounced C-terminal titin abnormality than expected for heterozygous mutants in all six probands, suggesting the existence of additional TTN mutations. RT-PCR indicated unequal mRNA expression of the two TTN alleles in biopsies of four patients, two of them with an LGMD2J phenotype. TTN was analyzed by Sanger sequencing from genomic DNA of the patients. Three patients proved to be compound heterozygotes with novel TTN frameshift mutations combined with previously reported TMD mutations. One LGMD2J patient was heterozygous for the FINmaj TMD mutation with a likely second yet undiscovered mutation. The unequal expression levels of TTN transcripts in these four probands suggested that the expression of the frameshifted allele was severely reduced, probably through nonsense-mediated decay, explaining the observed more severe phenotypes. One Portuguese patient was homozygote for a previously known Spanish TMD mutation. This TMD mutation seems to cause a more severe TMD rather than LGMD2J when homozygous. One Finnish patient had FINmaj mutation combined with a novel missense mutation in the A-band region of titin causing a new phenotype completely different from previously described titinopathies. Our results further expand the complexity of muscular dystrophies caused by TTN mutations and suggest that the coexistence of second mutations may constitute a more common general mechanism of phenotype variability in muscular dystrophies.

Objective. Cytochrome c oxidase (COX) deficiency has been demonstrated in some patients with Alpers-Huttenlocher disease, but no genetic background has been identified. Our objective was to determine the molecular defect underlying the mitochondrial respiratory chain deficiency in a child with Alpers-Huttenlocher-like progressive cerebrohepatic disease. Methods. The entire coding region of mitochondrial DNA was analyzed by conformation-sensitive gel electrophoresis and sequencing. Biochemical and morphologic investigations were performed on tissue biopsy material, including oximetric and spectrophotometric analyses of oxidative phosphorylation, histochemistry, and electron microscopy. Results. Postmortem histologic examination revealed a marked loss of neurons in the olivary nuclei and a spongy change in the calcarine cortex, fatty infiltration and micronodular cirrhosis of the liver, and atrophic ovaries. A novel heteroplasmic 7706G>A mutation was found in the COX II gene. The median degree of the mutant heteroplasmy was 90% in 5 tissues examined but was lower in the blood of asymptomatic maternal relatives. The distribution of the mutant heteroplasmy was skewed to the left in single muscle fibers of the proband and her mother. The 7706G>A mutation converts a hydrophobic alanine in a conserved transmembrane segment to hydrophilic threonine. Conclusions. The 7706G>A mutation is pathogenic and may lead to impaired dioxygen transfer to the active site of COX. The clinical phenotype of this patient resembled that in Alpers-Huttenlocher disease, suggesting that analysis of mitochondrial DNA is worthwhile in patients with a progressive cerebrohepatic disease.

Peripheral neuropathy is one of the clinical manifestations of the MELAS (mitochondrial encephalopathy with lactic acidosis and stroke-like episodes) syndrome, but its frequency and phenotypic variability have not been properly characterised. We therefore studied the clinical and electrophysiological features of peripheral neuropathy in 32 patients with the 3243A > G mutation in mitochondrial DNA by using clinical examination, assessment of Neuropathy Symptom Score, Neuropathy Disability Score, and electrophysiological examinations. Seven patients (22 %; 95 % confidence interval, 9–40 %) fulfilled the electrodiagnostic criteria for polyneuropathy. Mixed axon loss and demyelinating sensorimotor neuropathy was the most common type of polyneuropathy, while one patient presented with uniform demyelinating sensorimotor polyneuropathy. Sensory more than motor neuropathy was diagnosed in four patients. Clinically and electrophysiologically confirmed carpal tunnel syndrome (CTS) occurred in three patients (9.4 %), suggesting a higher prevalence than in the general population. Patients with neuropathy were in general more severely affected than those without neuropathy, although no correlation was found between the presence of neuropathy and the degree of mutant heteroplasmy in muscle. Higher age and male gender were associated with an increased risk of neuropathy. Our results show that peripheral neuropathy is not uncommon in patients with the 3243A > G mutation, and they also may have an increased risk of CTS.

Hereditary myopathy with early respiratory failure (HMERF) is characterized by proximal–distal weakness and respiratory insufficiency in ambulant patients. The clinical onset of the disease is variable, ranging from early to late adulthood. Muscle weakness is typical in neck flexors, limb girdle, and in some cases also in distal lower limb muscles. A prominent early finding is respiratory muscle weakness presenting with an acute respiratory failure in many patients. A dominant mutation in the TTN kinase domain leading to HMERF has been described in a few families from Sweden. Very recently, two reports (in press) revealed a novel dominant A-band mutation in titin gene, TTN. This mutation (g.274375T>C; p.Cys30071Arg) was found in eight HMERF patients from three Swedish families and in 31 patients from three families. In our collaborative study we have identified the identical mutation in one Finnish family with four affected HMERF patients. In addition, the mutation was identified in one British patient, in one Italian patient and in one additional Swedish family. The patients had the same phenotype with progressive muscle weakness in the lower limbs and respiratory muscles, cytoplasmic bodies and rimmed vacuolar myopathy in muscle biopsy. Muscle MRI findings are pathognomonic with fatty degenerative changes in semitendinosus, obturatorius, sartorius, gracilis and iliopsoas muscles with variable involvement of anterior and lateral compartment and tibialis posterior on the lower legs. All patients carried the same haplotype including markers D2S2173 and D2S385 at the mutational locus. The shared genomic region is less than 3.3 Mb in size suggesting an ancestral founder, and indicating the existence of many undiagnosed families with this mutation.

Background: Large-scale mitochondrial DNA (mtDNA) deletions are associated with clinical conditions such as Kearns–Sayre syndrome and chronic progressive external ophthalmoplegia in adults and Pearson syndrome in children. Reported case series have suggested that deletions are not uncommon in the population, but their prevalence has not been documented. Methods: The authors ascertained patients with clinical features associated with mtDNA deletions in a defined adult population in northern Finland. Buccal epithelial samples were requested from each patient fulfilling the selection criteria, and full-length mtDNA was amplified using the long PCR method. Deletion breakpoints were identified using sequencing. Patients with deletions were examined clinically. Results: The authors identified four patients with single large-scale mtDNA deletions. The prevalence of deletions was calculated to be 1.6/100,000 in the adult population in the province of Northern Ostrobothnia (0.0 to 3.2; 95% CI). Analysis of incident cases from a neighboring province revealed two patients with deletions and yielded a similar population frequency. Conclusions: The frequency of large-scale mitochondrial DNA deletions is similar among populations, suggesting that there is a constant rate of new deletions.

Background: Mitochondrial diseases present with variable multi-organ symptoms. Common disease-causing mutations in mitochondrial DNA (mtDNA) are regularly screened in diagnostic work-up, but novel mutations may remain unnoticed. Methods: Patients (N = 66) with a clinical suspicion of mitochondrial disease were screened for their mtDNA coding region using conformation sensitive gel electrophoresis and sequencing. Long-PCR was used to detect deletions followed by POLG1 sequencing in patients with multiple deletions. Results: We discovered three novel mtDNA variants that included m.8743G > C, m.11322A > G and m.15933G > A. The novel MTTT variant m.15933G > A is suggested to be pathogenic. Analysis revealed also multiple mtDNA deletions in two patients and five nonsynonymous variants that were putatively pathogenic according to in-silico prediction algorithms. In addition, a rare haplogroup H associated m.7585_7586insT variant was discovered. Conclusion: Among patients with a suspected mitochondrial disease, a novel MTTT variant m.15933G > A was discovered and is suggested to be pathogenic. In addition, several putatively pathogenic nonsynonymous variants and rare variants were found. These findings highlight the importance of coding region mtDNA screening among patients with clinical features suggesting a mitochondrial disease, but who lack the common mitochondrial disease mutations.

Background The c.2447G>A (p.R722H) mutation in the gene POLG1 of the catalytic subunit of human mitochondrial polymerase gamma has been previously found in a few occasions but its pathogenicity has remained uncertain. We set out to ascertain its contribution to neuromuscular disease. Methods Probands from two families with probable mitochondrial disease were examined clinically, muscle and buccal epithelial DNA were analyzed for mtDNA deletions, and the POLG1, POLG2, ANT1 and Twinkle genes were sequenced. Results An adult proband presented with progressive external ophthalmoplegia, sensorineural hearing impairment, diabetes mellitus, dysphagia, a limb myopathy and dementia. Brain MRI showed central and cortical atrophy, and 18F-deoxyglucose PET revealed reduced glucose uptake. Histochemical analysis of muscle disclosed ragged red fibers and cytochrome c oxidase-negative fibers. Electron microscopy showed subsarcolemmal aggregates of morphologically normal mitochondria. Multiple mtDNA deletions were found in the muscle, and sequencing of the POLG1 gene revealed a homozygous c.2447G>A (p.R722H) mutation. His two siblings were also homozygous with respect to the p.R722H mutation and presented with dementia and sensorineural hearing impairment. In another family the p.R722H mutation was found as compound heterozygosity with the common p.W748S mutation in two siblings with mental retardation, ptosis, epilepsy and psychiatric symptoms. The estimated carrier frequency of the p.R722H mutation was 1:135 in the Finnish population. No mutations in POLG2, ANT1 and Twinkle genes were found. Analysis of the POLG1 sequence by homology modeling supported the notion that the p.R722H mutation is pathogenic. Conclusions The recessive c.2447G>A (p.R722H) mutation in the linker region of the POLG1 gene is pathogenic for multiple mtDNA deletions in muscle and is associated with a late-onset neurological phenotype as a homozygous state. The onset of the disease can be earlier in compound heterozygotes.