Thomas Klopstock
Research interests
-
InterestsNeurological Diseases
Publications
-
3.49Impact points
A high-throughput resequencing microarray for autosomal dominant spastic paraplegia genes.
Neurogenetics. 05/2012;
Hereditary spastic paraplegias (HSP) are a heterogeneous group of neurological disorders. Insidiously progressive spastic weakness of the lower extremities is the common criterion in all forms described. Clinically, HSP is differentiated into pure (uncomplicated) and complex (complicated) forms. Whi... [more] Hereditary spastic paraplegias (HSP) are a heterogeneous group of neurological disorders. Insidiously progressive spastic weakness of the lower extremities is the common criterion in all forms described. Clinically, HSP is differentiated into pure (uncomplicated) and complex (complicated) forms. While pure HSP is predominantly characterized by signs and symptoms of pyramidal tract dysfunction, additional neurological and non-neurological symptoms occur in complicated forms. Autosomal dominant, autosomal recessive, and X-linked modes of inheritance have been described and at least 48 subtypes, termed SPG1-48, have been genetically defined. Although in autosomal dominant HSP families 50-60% of etiologies can be established by genetic testing, genotype predictions based on the phenotype are limited. In order to realize high-throughput genotyping for dominant HSP, we designed a resequencing microarray for six autosomal dominant genes on the Affymetrix CustomSEQ array platform. For validation purposes, 10 previously Sanger sequenced patients with autosomal dominant HSP and 40 positive controls with known mutations in ATL1, SPAST, NIPA1, KIF5A, and BSCL2 (32 base exchanges, eight small indels) were resequenced on this array. DNA samples of 45 additional patients with AD spastic paraplegia were included in the study. With two different sequencing analysis software modules (GSEQ, SeqC), all missense/nonsense mutations in the positive controls were identified while indels had a detection rate of only 50%. In total, 244 common synonymous single-nucleotide polymorphisms (SNPs) annotated in dbSNP (build 132) corresponding to 22 distinct sequence variations were found in the 53 analyzed patients. Among the 22 different sequence variations (SPAST n = 15, ATL1 n = 3, KIF5A n = 2, HSPD1 n = 1, BSCL2 n = 1, NIPA1 n = 0), 12 were rare variants that have not been previously described and whose clinical significance is unknown. In SPAST-negative cases, a genetic diagnosis could be established in 11% by resequencing. Resequencing microarray technology can therefore efficiently be used to study genotypes and mutations in large patient cohorts.
-
5.75Impact points
Molecular diagnosis in mitochondrial complex I deficiency using exome sequencing.
Journal of medical genetics. 04/2012; 49(4):277-83.
Background Next generation sequencing has become the core technology for gene discovery in rare inherited disorders. However, the interpretation of the numerous sequence variants identified remains challenging. We assessed the application of exome sequencing for diagnostics in complex I deficiency, ... [more] Background Next generation sequencing has become the core technology for gene discovery in rare inherited disorders. However, the interpretation of the numerous sequence variants identified remains challenging. We assessed the application of exome sequencing for diagnostics in complex I deficiency, a disease with vast genetic heterogeneity. Methods Ten unrelated individuals with complex I deficiency were selected for exome sequencing and sequential bioinformatic filtering. Cellular rescue experiments were performed to verify pathogenicity of novel disease alleles. Results The first filter criterion was 'Presence of known pathogenic complex I deficiency variants'. This revealed homozygous mutations in NDUFS3 and ACAD9 in two individuals. A second criterion was 'Presence of two novel potentially pathogenic variants in a structural gene of complex I', which discovered rare variants in NDUFS8 in two unrelated individuals and in NDUFB3 in a third. Expression of wild-type cDNA in mutant cell lines rescued complex I activity and assembly, thus providing a functional validation of their pathogenicity. Using the third criterion 'Presence of two potentially pathogenic variants in a gene encoding a mitochondrial protein', loss-of-function mutations in MTFMT were discovered in two patients. In three patients the molecular genetic correlate remained unclear and follow-up analysis is ongoing. Conclusion Appropriate in silico filtering of exome sequencing data, coupled with functional validation of new disease alleles, is effective in rapidly identifying disease-causative variants in known and new complex I associated disease genes.
-
9.53Impact points
Neurobeachin, a regulator of synaptic protein targeting, is associated with body fat mass and feeding behavior in mice and body-mass index in humans.
PLoS genetics. 03/2012; 8(3):e1002568.
Neurobeachin (Nbea) regulates neuronal membrane protein trafficking and is required for the development and functioning of central and neuromuscular synapses. In homozygous knockout (KO) mice, Nbea deficiency causes perinatal death. Here, we report that heterozygous KO mice haploinsufficient for Nbe... [more] Neurobeachin (Nbea) regulates neuronal membrane protein trafficking and is required for the development and functioning of central and neuromuscular synapses. In homozygous knockout (KO) mice, Nbea deficiency causes perinatal death. Here, we report that heterozygous KO mice haploinsufficient for Nbea have higher body weight due to increased adipose tissue mass. In several feeding paradigms, heterozygous KO mice consumed more food than wild-type (WT) controls, and this consumption was primarily driven by calories rather than palatability. Expression analysis of feeding-related genes in the hypothalamus and brainstem with real-time PCR showed differential expression of a subset of neuropeptide or neuropeptide receptor mRNAs between WT and Nbea+/- mice in the sated state and in response to food deprivation, but not to feeding reward. In humans, we identified two intronic NBEA single-nucleotide polymorphisms (SNPs) that are significantly associated with body-mass index (BMI) in adult and juvenile cohorts. Overall, data obtained in mice and humans suggest that variation of Nbea abundance or activity critically affects body weight, presumably by influencing the activity of feeding-related neural circuits. Our study emphasizes the importance of neural mechanisms in body weight control and points out NBEA as a potential risk gene in human obesity.
-
4.01Impact points
Locomotion speed determines gait variability in cerebellar ataxia and vestibular failure.
Movement disorders : official journal of the Movement Disorder Society. 01/2012; 27(1):125-31.
Temporal gait variability is a critical parameter in patients with balance problems. Increased magnitude of temporal gait variability corresponds to a higher risk of falls. The purpose of this study was to investigate the influence of walking speed on temporal stride-to-stride variability in patient... [more] Temporal gait variability is a critical parameter in patients with balance problems. Increased magnitude of temporal gait variability corresponds to a higher risk of falls. The purpose of this study was to investigate the influence of walking speed on temporal stride-to-stride variability in patients with cerebellar and vestibular deficits. A GAITRite system was used to analyze the gait of 40 patients with cerebellar ataxia, 22 patients with bilateral vestibular failure, and 51 healthy subjects over the entire range of the individual's speed capacity. The coefficient of variability of stride time was calculated for each walk. Temporal gait variability was increased in cerebellar patients and vestibular patients. The magnitude of this variability depended on walking speed in a disease-specific manner. In patients with cerebellar ataxia, variability was increased during slow (8.4 ± 5.3%, P < .01) and fast (7.9 ± 6.4%, P < .01) walking speed but was normal during preferred walking speed. This resulted in a speed-related U-shaped function of stride-time variability. Patients with vestibular failure had increased variability during slow walking (9.9 ± 4.3%, P < .01). During walking with medium and fast walking speed, stride time variability was normal. Minimal temporal gait variability appears to be attractive for the locomotor system in cerebellar patients because these patients preferred to walk at a velocity associated with minimal stride-time variability. In contrast to previous studies, vestibular patients accelerate rather than decelerate gait to achieve dynamic stability. This may be explained by reduced sensory integration during fast locomotion.
-
Neuromelanin, neurotransmitter status and brainstem location determine the differential vulnerability of catecholaminergic neurons to mitochondrial DNA deletions.
Molecular brain. 12/2011; 4:43.
ABSTRACT: Deletions of the mitochondrial DNA (mtDNA) accumulate to high levels in dopaminergic neurons of the substantia nigra pars compacta (SNc) in normal aging and in patients with Parkinson's disease (PD). Human nigral neurons characteristically contain the pigment neuromelanin (NM), which i... [more] ABSTRACT: Deletions of the mitochondrial DNA (mtDNA) accumulate to high levels in dopaminergic neurons of the substantia nigra pars compacta (SNc) in normal aging and in patients with Parkinson's disease (PD). Human nigral neurons characteristically contain the pigment neuromelanin (NM), which is believed to alter the cellular redox-status. The impact of neuronal pigmentation, neurotransmitter status and brainstem location on the susceptibility to mtDNA damage remains unclear. We quantified mtDNA deletions (ΔmtDNA) in single pigmented and non-pigmented catecholaminergic, as well as non-catecholaminergic neurons of the human SNc, the ventral tegmental area (VTA) and the locus coeruleus (LC), using laser capture microdissection and single-cell real-time PCR. In healthy aged individuals, ΔmtDNA levels were highest in pigmented catecholaminergic neurons (25.2 ± 14.9%), followed by non-pigmented catecholamergic (18.0 ± 11.2%) and non-catecholaminergic neurons (12.3 ± 12.3%; p < 0.001). Within the catecholaminergic population, ΔmtDNA levels were highest in dopaminergic neurons of the SNc (33.9 ± 21.6%) followed by dopaminergic neurons of the VTA (21.9 ± 12.3%) and noradrenergic neurons of the LC (11.1 ± 11.4%; p < 0.001). In PD patients, there was a trend to an elevated mutation load in surviving non-pigmented nigral neurons (27.13 ± 16.73) compared to age-matched controls (19.15 ± 11.06; p = 0.052), but levels where similar in pigmented nigral neurons of PD patients (41.62 ± 19.61) and controls (41.80 ± 22.62). Catecholaminergic brainstem neurons are differentially susceptible to mtDNA damage. Pigmented dopaminergic neurons of the SNc show the highest ΔmtDNA levels, possibly explaining the exceptional vulnerability of the nigro-striatal system in PD and aging. Although loss of pigmented noradrenergic LC neurons also is an early feature of PD pathology, mtDNA levels are not elevated in this nucleus in healthy controls. Thus, ΔmtDNA are neither an inevitable consequence of catecholamine metabolism nor a universal explanation for the regional vulnerability seen in PD.
-
12.30Impact points
Absence of an orphan mitochondrial protein, c19orf12, causes a distinct clinical subtype of neurodegeneration with brain iron accumulation.
American journal of human genetics. 10/2011; 89(4):543-50.
The disease classification neurodegeneration with brain iron accumulation (NBIA) comprises a clinically and genetically heterogeneous group of progressive neurodegenerative disorders characterized by brain iron deposits in the basal ganglia. For about half of the cases, the molecular basis is curren... [more] The disease classification neurodegeneration with brain iron accumulation (NBIA) comprises a clinically and genetically heterogeneous group of progressive neurodegenerative disorders characterized by brain iron deposits in the basal ganglia. For about half of the cases, the molecular basis is currently unknown. We used homozygosity mapping followed by candidate gene sequencing to identify a homozygous 11 bp deletion in the orphan gene C19orf12. Mutation screening of 23 ideopathic NBIA index cases revealed two mutated alleles in 18 of them, and one loss-of-function mutation is the most prevalent. We also identified compound heterozygous missense mutations in a case initially diagnosed with Parkinson disease at age 49. Psychiatric signs, optic atrophy, and motor axonal neuropathy were common findings. Compared to the most prevalent NBIA subtype, pantothenate kinase associated neurodegeneration (PKAN), individuals with two C19orf12 mutations were older at age of onset and the disease progressed more slowly. A polyclonal antibody against the predicted membrane spanning protein showed a mitochondrial localization. A histopathological examination in a single autopsy case detected Lewy bodies, tangles, spheroids, and tau pathology. The mitochondrial localization together with the immunohistopathological findings suggests a pathomechanistic overlap with common forms of neurodegenerative disorders.
-
9.49Impact points
A randomized placebo-controlled trial of idebenone in Leber's hereditary optic neuropathy.
Brain : a journal of neurology. 07/2011; 134(Pt 9):2677-86.
Major advances in understanding the pathogenesis of inherited metabolic disease caused by mitochondrial DNA mutations have yet to translate into treatments of proven efficacy. Leber's hereditary optic neuropathy is the most common mitochondrial DNA disorder causing irreversible blindness in youn... [more] Major advances in understanding the pathogenesis of inherited metabolic disease caused by mitochondrial DNA mutations have yet to translate into treatments of proven efficacy. Leber's hereditary optic neuropathy is the most common mitochondrial DNA disorder causing irreversible blindness in young adult life. Anecdotal reports support the use of idebenone in Leber's hereditary optic neuropathy, but this has not been evaluated in a randomized controlled trial. We conducted a 24-week multi-centre double-blind, randomized, placebo-controlled trial in 85 patients with Leber's hereditary optic neuropathy due to m.3460G>A, m.11778G>A, and m.14484T>C or mitochondrial DNA mutations. The active drug was idebenone 900 mg/day. The primary end-point was the best recovery in visual acuity. The main secondary end-point was the change in best visual acuity. Other secondary end-points were changes in visual acuity of the best eye at baseline and changes in visual acuity for both eyes in each patient. Colour-contrast sensitivity and retinal nerve fibre layer thickness were measured in subgroups. Idebenone was safe and well tolerated. The primary end-point did not reach statistical significance in the intention to treat population. However, post hoc interaction analysis showed a different response to idebenone in patients with discordant visual acuities at baseline; in these patients, all secondary end-points were significantly different between the idebenone and placebo groups. This first randomized controlled trial in the mitochondrial disorder, Leber's hereditary optic neuropathy, provides evidence that patients with discordant visual acuities are the most likely to benefit from idebenone treatment, which is safe and well tolerated.
-
6.40Impact points
Expression analysis of dopaminergic neurons in Parkinson's disease and aging links transcriptional dysregulation of energy metabolism to cell death.
Acta neuropathologica. 07/2011; 122(1):75-86.
Dopaminergic (DA) neuron degeneration is a feature of brain aging but is markedly increased in patients with Parkinson's disease (PD). Recent data indicate elevated metabolic stress as a possible explanation for DA neuron vulnerability. Using laser capture microdissection, we isolated DA neurons... [more] Dopaminergic (DA) neuron degeneration is a feature of brain aging but is markedly increased in patients with Parkinson's disease (PD). Recent data indicate elevated metabolic stress as a possible explanation for DA neuron vulnerability. Using laser capture microdissection, we isolated DA neurons from the substantia nigra pars compacta of PD patients, age-matched and young controls to determine transcriptional changes by expression profiling and pathway analysis. We verified our findings by comparison to a published dataset. Parallel processing of isolated neurons and bulk tissue allowed the discrimination of neuronal and glial transcription signals. Our data show that genes known to be involved in neural plasticity, axon and synaptic function, as well as cell fate are differentially regulated in aging DA neurons. The transcription patterns in aging suggest a largely maintained expression of genes in energy-related pathways in surviving neurons, possibly supported by the mediation of PPAR/RAR and CREB signaling. In contrast, a profound down-regulation of genes coding for mitochondrial and ubiquitin--proteasome system proteins was seen in PD when compared to the age-matched controls. This is in accordance with the established mitochondrial dysfunction in PD and provides evidence for mitochondrial impairment at the transcriptional level. In addition, the PD neurons had disrupted pathways that comprise a network involved in the control of energy metabolism and cell survival in response to growth factors, oxidative stress, and nutrient deprivation (PI3K/Akt, mTOR, eIF4/p70S6K and Hif-1α). PI3K/Akt and mTOR signaling are central hubs of this network which is of relevance to longevity and--together with induction of mitochondrial biogenesis--may constitute potential targets for therapeutic intervention.
-
5.33Impact points
Requirement of the RNA-editing enzyme ADAR2 for normal physiology in mice.
The Journal of biological chemistry. 04/2011; 286(21):18614-22.
ADAR2, an RNA editing enzyme that converts specific adenosines to inosines in certain pre-mRNAs, often leading to amino acid substitutions in the encoded proteins, is mainly expressed in brain. Of all ADAR2-mediated edits, a single one in the pre-mRNA of the AMPA receptor subunit GluA2 is essential ... [more] ADAR2, an RNA editing enzyme that converts specific adenosines to inosines in certain pre-mRNAs, often leading to amino acid substitutions in the encoded proteins, is mainly expressed in brain. Of all ADAR2-mediated edits, a single one in the pre-mRNA of the AMPA receptor subunit GluA2 is essential for survival. Hence, early postnatal death of mice lacking ADAR2 is averted when the critical edit is engineered into both GluA2 encoding Gria2 alleles. Adar2(-/-)/Gria2(R/R) mice display normal appearance and life span, but the general phenotypic effects of global lack of ADAR2 have remained unexplored. Here we have employed the Adar2(-/-)/Gria2(R/R) mouse line, and Gria2(R/R) mice as controls, to study the phenotypic consequences of loss of all ADAR2-mediated edits except the critical one in GluA2. Our extended phenotypic analysis covering ∼320 parameters identified significant changes related to absence of ADAR2 in behavior, hearing ability, allergy parameters and transcript profiles of brain.
-
4.01Impact points
Depression comorbidity in spinocerebellar ataxia.
Movement disorders : official journal of the Movement Disorder Society. 03/2011; 26(5):870-6.
This is a description of the prevalence and profile of depressive symptoms in dominant spinocerebellar ataxia (SCA). Depressive symptoms were assessed in a convenience sample of 526 genetically confirmed and clinically affected patients (117 SCA1, 163 SCA2, 139 SCA3, and 107 SCA6) using the Patient ... [more] This is a description of the prevalence and profile of depressive symptoms in dominant spinocerebellar ataxia (SCA). Depressive symptoms were assessed in a convenience sample of 526 genetically confirmed and clinically affected patients (117 SCA1, 163 SCA2, 139 SCA3, and 107 SCA6) using the Patient Health Questionnaire (PHQ). In addition, depressive status according to the examiner and the use of antidepressants was recorded. Depression self-assessment was compared with an interview-based psychiatric assessment in a subset of 26 patients. Depression prevalence estimates were 17.1% according to the PHQ algorithm and 15.4% when assessed clinically. The sensitivity of clinical impression compared with PHQ classification was low (0.35), whereas diagnostic accuracy of PHQ compared with psychiatric interview in the subset was high. Antidepressants were used by 17.7% of patients and in >10% of patients without current clinically relevant depressive symptoms. Depression profile in SCA did not differ from a sample of patients with major depressive disorder except for the movement-related item. Neither depression prevalence nor use of antidepressants differed between genetic subtypes, with only sleep disturbance more common in SCA3. In a multivariate analysis, ataxia severity and female sex independently predicted depressive status in SCA. The PHQ algorithmic classification is appropriate for use in SCA but should stimulate further psychiatric evaluation if depression is indicated. Despite a higher risk for depression with more severe disease, the relation of depressive symptoms to SCA neurodegeneration remains to be shown.
-
3.76Impact points
Mouse phenotyping.
Methods (San Diego, Calif.). 02/2011; 53(2):120-35.
Model organisms like the mouse are important tools to learn more about gene function in man. Within the last 20 years many mutant mouse lines have been generated by different methods such as ENU mutagenesis, constitutive and conditional knock-out approaches, knock-down, introduction of human genes, ... [more] Model organisms like the mouse are important tools to learn more about gene function in man. Within the last 20 years many mutant mouse lines have been generated by different methods such as ENU mutagenesis, constitutive and conditional knock-out approaches, knock-down, introduction of human genes, and knock-in techniques, thus creating models which mimic human conditions. Due to pleiotropic effects, one gene may have different functions in different organ systems or time points during development. Therefore mutant mouse lines have to be phenotyped comprehensively in a highly standardized manner to enable the detection of phenotypes which might otherwise remain hidden. The German Mouse Clinic (GMC) has been established at the Helmholtz Zentrum München as a phenotyping platform with open access to the scientific community (www.mousclinic.de; [1]). The GMC is a member of the EUMODIC consortium which created the European standard workflow EMPReSSslim for the systemic phenotyping of mouse models (http://www.eumodic.org/[2]).
-
7.48Impact points
Identification of rare DNA variants in mitochondrial disorders with improved array-based sequencing.
Nucleic acids research. 01/2011; 39(1):44-58.
A common goal in the discovery of rare functional DNA variants via medical resequencing is to incur a relatively lower proportion of false positive base-calls. We developed a novel statistical method for resequencing arrays (SRMA, sequence robust multi-array analysis) to increase the accuracy of det... [more] A common goal in the discovery of rare functional DNA variants via medical resequencing is to incur a relatively lower proportion of false positive base-calls. We developed a novel statistical method for resequencing arrays (SRMA, sequence robust multi-array analysis) to increase the accuracy of detecting rare variants and reduce the costs in subsequent sequence verifications required in medical applications. SRMA includes single and multi-array analysis and accounts for technical variables as well as the possibility of both low- and high-frequency genomic variation. The confidence of each base-call was ranked using two quality measures. In comparison to Sanger capillary sequencing, we achieved a false discovery rate of 2% (false positive rate 1.2 × 10⁻⁵, false negative rate 5%), which is similar to automated second-generation sequencing technologies. Applied to the analysis of 39 nuclear candidate genes in disorders of mitochondrial DNA (mtDNA) maintenance, we confirmed mutations in the DNA polymerase gamma POLG in positive control cases, and identified novel rare variants in previously undiagnosed cases in the mitochondrial topoisomerase TOP1MT, the mismatch repair enzyme MUTYH, and the apurinic-apyrimidinic endonuclease APEX2. Some patients carried rare heterozygous variants in several functionally interacting genes, which could indicate synergistic genetic effects in these clinically similar disorders.
-
4.01Impact points
Grasping premanifest Huntington's disease - shaping new endpoints for new trials.
Movement disorders : official journal of the Movement Disorder Society. 12/2010; 25(16):2858-62.
Future clinical trials in subjects with premanifest Huntington's disease (preHD) may depend on the availability of biomarkers. It was previously shown in symptomatic HD that, the grip force variability coefficient-of-variation (GFV-C) in a grasping paradigm was correlated to the Unified-Huntingt... [more] Future clinical trials in subjects with premanifest Huntington's disease (preHD) may depend on the availability of biomarkers. It was previously shown in symptomatic HD that, the grip force variability coefficient-of-variation (GFV-C) in a grasping paradigm was correlated to the Unified-Huntington's-Disease-Rating-Scale-Total-Motor-Score (UHDRS-TMS) and increased in a 3 year follow-up study. To further elucidate its potential as a biomarker, we investigated whether GFV-C is able to detect a motor phenotype in preHD and is correlated to the genotype assessed by a disease-burden-score. The ability of preHD (n = 15) and symptomatic HD subjects (n = 20) to maintain stable grip forces, while holding an object (250 g and 500 g), was measured and compared with the controls (n = 19). GFV-C was increased in preHD at 500 g, in symptomatic subjects at both weights and was correlated to the disease-burden-score and UHDRS-TMS. GFV-C may be a useful objective and quantitative marker of motor dysfunction across genetically diagnosed premanifest and symptomatic HD subjects.
-
4.01Impact points
Tongue force analysis assesses motor phenotype in premanifest and symptomatic Huntington's disease.
Movement disorders : official journal of the Movement Disorder Society. 10/2010; 25(13):2195-202.
Motor symptoms in Huntington's Disease (HD) are commonly assessed by the Unified Huntington's Disease Rating Scale-Total Motor Score (UHDRS-TMS). However, the UHDRS-TMS is limited by interrater variability, its categorical nature, and insensitivity in premanifest subjects. More objective and... [more] Motor symptoms in Huntington's Disease (HD) are commonly assessed by the Unified Huntington's Disease Rating Scale-Total Motor Score (UHDRS-TMS). However, the UHDRS-TMS is limited by interrater variability, its categorical nature, and insensitivity in premanifest subjects. More objective and quantitative measures of motor phenotype may complement the use of the UHDRS-TMS as outcome measure and increase the power and sensitivity of clinical trials. Deficits in tongue protrusion are well acknowledged in HD and constitute a subitem of the UHDRS-TMS. We, therefore, investigated whether objective and quantitative assessment of tongue protrusion forces (TPF) provides measures that (1) correlate to the severity of motor phenotype detected in the UHDRS-TMS in symptomatic HD, (2) detect a motor phenotype in premanifest HD gene-carriers, and (3) exhibit a correlation to the genotype as assessed by a disease burden score (based on CAG-repeat length and age). Using a precalibrated force transducer, the ability of premanifest gene carriers (n = 15) and subjects with symptomatic HD (n = 20) to generate and maintain isometric TPF at three target force levels (0.25, 0.5, and 1.0 N) was assessed and compared with age-matched controls (n = 20) in a cross-sectional study. Measures of variability of TPF and tongue contact time distinguished controls, premanifest, and symptomatic HD groups and correlated to the UHDRS-TMS and disease burden score, suggesting a strong genotype-phenotype correlation. Group distinction was most reliable at the lowest target force level. We conclude that assessment of TPF may be a useful objective and quantitative marker of motor dysfunction in premanifest and symptomatic HD.
-
2.90Impact points
Late-onset ptosis and myopathy in a patient with a heterozygous insertion in POLG2.
Journal of neurology. 09/2010; 257(9):1517-23.
Polymerase gamma 1 (POLG) mutations are a frequent cause of both autosomal dominant and recessive complex neurological phenotypes. In contrast, only a single pathogenic mutation in one patient was reported in POLG2 so far. Here we describe a 62-year-old woman, carrying a novel heterozygous sequence ... [more] Polymerase gamma 1 (POLG) mutations are a frequent cause of both autosomal dominant and recessive complex neurological phenotypes. In contrast, only a single pathogenic mutation in one patient was reported in POLG2 so far. Here we describe a 62-year-old woman, carrying a novel heterozygous sequence variant in the POLG2 gene. She developed bilateral ptosis at 30 years of age, followed by exercise intolerance, muscle weakness and mild CK increase in her late forties. Muscle histology and respiratory chain activities were normal. Southern blot and long range PCR detected multiple mtDNA deletions, but no depletion in muscle DNA. Sequencing of POLG, PEO1, ANT1, OPA1 and RRM2B showed normal results. A novel heteroallelic 24 bp insertion (c.1207_1208ins24) was detected in POLG2. This 24 bp insertion into exon 7 causes missplicing and loss of exon 7 in myoblast cDNA. We did not detect POLG2 mutations in 62 patients with multiple mtDNA deletions in muscle DNA, suggesting that POLG2 mutations may represent a rare cause of autosomal dominant PEO.
-
2.98Impact points
The pathogenic m.3243A>T mitochondrial DNA mutation is associated with a variable neurological phenotype.
Neuromuscular disorders : NMD. 06/2010; 20(6):403-6.
The m.3243A>G point mutation in the mitochondrial tRNA(Leu(UUR)) (MTTL1) gene is a common cause of mitochondrial DNA disease and is associated with a variety of clinical presentations. A different mutation occurring at the same site - an m.3243A>T transversion - is less prevalent, but has prev... [more] The m.3243A>G point mutation in the mitochondrial tRNA(Leu(UUR)) (MTTL1) gene is a common cause of mitochondrial DNA disease and is associated with a variety of clinical presentations. A different mutation occurring at the same site - an m.3243A>T transversion - is less prevalent, but has previously been observed in two patients with encephalopathy and lactic acidosis. We report the investigations of a further two patients with the m.3243A>T mutation who presented with either a chronic progressive external ophthalmoplegia (CPEO) phenotype or sensorineural hearing loss, with single fibre mutation studies confirming segregation of the m.3243A>T mutation with COX deficiency.
-
0.96Impact points
MELAS: a mitochondrial disorder in an adult patient with a renal transplant.
Wiener klinische Wochenschrift. 06/2010; 122(11-12):363-5.
Mitochondrial diseases are a heterogeneous group of syndromes caused by genetic defects in mitochondrial DNA (mtDNA) or nuclear-encoded mitochondrial genes. They present with a wide range of clinical phenotypes. Myopathy may be the sole or main sign, or merely an incidental finding occurring in the ... [more] Mitochondrial diseases are a heterogeneous group of syndromes caused by genetic defects in mitochondrial DNA (mtDNA) or nuclear-encoded mitochondrial genes. They present with a wide range of clinical phenotypes. Myopathy may be the sole or main sign, or merely an incidental finding occurring in the late course of a multisystemic illness. Although mitochondrial disorders are increasingly being recognized, confirming a specific diagnosis remains a great challenge due to the clinical heterogeneity of the diseases. Several well-defined clinical syndromes associated with specific mutations have been described. Thus, suspicion of mitochondrial diseases among patients with multiple, seemingly unrelated neuromuscular and multisystem disorders should be confirmed by the finding of deleterious mutations in genes involving mitochondrial biogenesis and function. This case report describes a 58-year-old patient with a 40-year course of a multisystemic illness representing the diagnostic challenges of mitochondrial disease.
-
2.94Impact points
Microphthalmia, parkinsonism, and enhanced nociception in Pitx3 ( 416insG ) mice.
Mammalian genome : official journal of the International Mammalian Genome Society. 02/2010; 21(1-2):13-27.
A new spontaneous mouse mutant was characterized by closed eyelids at weaning and without apparent eyes (provisional gene name, eyeless; provisional gene symbol, eyl). The mutation follows a recessive pattern of inheritance and was mapped to the region of chromosome 19 containing Pitx3. Genetic comp... [more] A new spontaneous mouse mutant was characterized by closed eyelids at weaning and without apparent eyes (provisional gene name, eyeless; provisional gene symbol, eyl). The mutation follows a recessive pattern of inheritance and was mapped to the region of chromosome 19 containing Pitx3. Genetic complementation tests using Pitx3 ( ak/+ ) mice confirmed eyl as a new allele of Pitx3 (Pitx3 ( eyl )). Sequencing of the Pitx3 gene in eyl mutants identified an inserted G after cDNA position 416 (416insG; exon 4). The shifted open reading frame is predicted to result in a hybrid protein still containing the Pitx3 homeobox, but followed by 121 new amino acids. The novel Pitx3 ( eyl/eyl ) mutants expressed ophthalmological and brain defects similar to Pitx3 ( ak/ak ) mice: microphthalmia or anophthalmia and loss of dopamine neurons of the substantia nigra. In addition, we observed in the homozygous eyeless mutants increased extramedullary hematopoiesis in the spleen, frequently liver steatosis, and reduced body weight. There were also several behavioral changes in the homozygous mutants, including reduced forelimb grip strength and increased nociception. In addition to these alterations in both sexes, we observed in female Pitx3 ( eyl/eyl ) mice increased anxiety-related behavior, reduced locomotor activity, reduced object exploration, and increased social contacts; however, we observed decreased anxiety-related behavior and increased arousal in males. Most of these defects identified in the new Pitx3 mutation are observed in Parkinson patients, making the Pitx3 ( eyl ) mutant a valuable new model. It is the first mouse mutant carrying a point mutation within the coding region of Pitx3.
-
4.01Impact points
Self-rated health status in spinocerebellar ataxia--results from a European multicenter study.
Movement disorders : official journal of the Movement Disorder Society. 02/2010; 25(5):587-95.
Patient-based measures of subjective health status are increasingly used as outcome measures in interventional trials. We aimed to determine the variability and predictors of subjective health ratings in a possible target group for future interventions: the spinocerebellar ataxias (SCAs). A consecut... [more] Patient-based measures of subjective health status are increasingly used as outcome measures in interventional trials. We aimed to determine the variability and predictors of subjective health ratings in a possible target group for future interventions: the spinocerebellar ataxias (SCAs). A consecutive sample of 526 patients with otherwise unexplained progressive ataxia and genetic diagnoses of SCA1 (117), SCA2 (163), SCA3 (139), and SCA6 (107) were enrolled at 18 European referral centers. Subjective health status was assessed with a generic measure of health related quality of life, the EQ-5D (Euroqol) questionnaire. In addition, we performed a neurological examination and a screening questionnaire for affective disorders (patient health questionnaire). Patient-reported health status was compromised in patients of all genotypes (EQ-5D visual analogue scale (EQ-VAS) mean 61.45 +/- 20.8). Specifically, problems were reported in the dimensions of mobility (86.9% of patients), usual activities (68%), pain/discomfort (49.4%), depression/anxiety (46.4%), and self care (38.2%). Multivariate analysis revealed three independent predictors of subjective health status: ataxia severity, extent of noncerebellar involvement, and the presence of depressive syndrome. This model explained 30.5% of EQ-VAS variance in the whole sample and might be extrapolated to other SCA genotypes.
-
Konzept für ein deutschlandweites Krankheitsnetz am Beispiel von mitoREGISTER.
Informatik 2010: Service Science - Neue Perspektiven für die Informatik, Beiträge der 40. Jahrestagung der Gesellschaft für Informatik e.V. (GI), Band 2, 27.09. - 1.10.2010, Leipzig; 01/2010
Following (33)
-
Sabine M Hölter
Helmholtz Zentrum München -
Gerhard Heldmaier
Philipps-Universität Marburg -
Ralf Elvert
Sanofi S.A. -
Werner Muller
The University of Manchester -
Martin Klingenspor
Technische Universität München
Topics (2)
