Thorsten Schulte

Autosomal dominant cerebellar ataxias: clinical features, genetics, and pathogenesis

Autosomal dominant cerebellar ataxias are hereditary neurodegenerative disorders that are known as spinocerebellar ataxias (SCA) in genetic nomenclature. In the pregenomic era, ataxias were some of the most poorly understood neurological disorders; the unravelling of their molecular basis enabled precise diagnosis in vivo and explained many clinical phenomena such as anticipation and variable phenotypes even within one family. However, the discovery of many ataxia genes and loci in the past decade threatens to cause more confusion than optimism among clinicians. Therefore, the provision of guidance for genetic testing according to clinical findings and frequencies of SCA subtypes in different ethnic groups is a major challenge. The identification of ataxia genes raises hope that essential pathogenetic mechanisms causing SCA will become more and more apparent. Elucidation of the pathogenesis of SCA hopefully will enable the development of rational therapies for this group of disorders, which currently can only be treated symptomatically.

Polymorphisms in the interleukin-1 alpha and beta genes and the risk for Parkinson's disease.

Several lines of evidence indicate that immune mechanisms are involved in the pathogenesis of neurodegenerative disorders. Activated immunocompetent cells and inflammatory cytokines are present in affected brain regions in patients with Alzheimers (AD) and Parkinsons disease (PD). For AD biochemical and pathological data are supported by genetic studies identifying risk alleles for polymorphisms in regulatory regions of the interleukin-1 alpha (IL-1 alpha-889) and interleukin-1 beta (IL-1 beta-511) gene, respectively. The partially overlapping pathology and inflammatory reaction pattern between AD and PD led us to investigate these polymorphisms in a large sample of 295 German PD patients and 270 healthy controls. We found T in position -511 in the IL-1 beta gene more frequent in patients compared to controls (chi(2)=4.44, P=0.034). For the IL-1 alpha-889 polymorphism no significant difference between patients and controls was observed.

Do CTG expansions at the SCA8 locus cause ataxia

To evaluate the significance of expanded CTG repeats at the SCA8 locus, we analyzed the allele distribution in 1,262 German ataxia patients. We found intermediate and expanded CTG repeats with similar frequencies in ataxia patients with and without established genetic diseases. One family linked to the SCA8 locus showed incomplete penetrance and an association of smaller CTG repeats with more severe disease. Our data question the disease‐causing character of CTG expansions for SCA8 and advise great caution in genetic testing. Ann Neurol 2003;54:110–115

Mutation analysis of the neurofilament M gene in Parkinson's disease.

Neurofilament M, a major component of Lewy bodies, represents an interesting candidate in the pathogenesis of Parkinsons disease (PD). We performed detailed mutation analyses of the NF-M gene in 322 familial and sporadic PD patients. Two polymorphisms (Ala475Thr and Gly697Arg) occurred at similar frequencies in PD patients and controls. A Pro725Gln substitution and a deletion of valine in position 829 were identified in two PD patients. These substitutions affect residues of the NF-M protein that are highly conserved among different species. None of our patients carried the Gly336Ser substitution, which has been described in familial PD. Our results argue against a major role of NF-M in PD. However, rare variants of the NF-M gene may act as susceptibility factors for PD and functional analyses of the identified variations are warranted to decipher possible mechanisms in neurodegeneration.

Intravenous amantadine sulphate application improves the performance of complex but not simple motor tasks in patients with Parkinson's disease

Intravenous application of amantadine sulphate induces a rapid improvement of motor symptoms in Parkinsons disease (PD), but there are no trials on the efficacy of this compound on bradykinesia, rigidity and tremor in detail in combination with standardized instrumental measurement of tapping and peg insertion abilities. We treated 31 stable non fluctuating PD patients with amantadine, scored motor symptoms of both arms and performed peg insertion and tapping under cued conditions before and after 3 days. Motor symptoms and peg insertion significantly improved in contrast to tapping. Tapping asks for repetitive performance of simple standardized movements, therefore it needs low cognitive efforts. Since peg insertion depends on more complex movements and thus more dopamine dependent cognitive processes, it improved after application of the indirect dopaminomimetic substance amantadine.

Treatment Benefit and Daily Drug Costs Associated with Treating Parkinson’s Disease in a Parkinson’s Disease Clinic

AbstractObjective: In some countries, such as Germany, there has been a move towards the treatment of patients with Parkinson’s disease in specialised inpatient units. However, data on patient outcome and the daily costs of antiparkinsonian drugs in these settings are rare. This study was conducted to determine the effect of an inpatient setting (a specialised Parkinson’s disease clinic) on drug therapy costs and patient symptoms. Patients and Methods: This study involved 63 consecutively referred inpatients of a Parkinson’s disease clinic. On entry to the clinic, the patients’ antiparkinsonian drug regimen was titrated in order to improve their motor function. The daily costs of drug therapy per patient (in 2002 values) were calculated, and the severity of Parkinson’s disease symptoms scored via scores on the Unified Parkinson’s Disease Rating Scale (UPDRS) and standardised instrumental procedures (peg insertion and tapping), both initially and at the end of the patients’ stay in the clinic. The variables between the two evaluation timepoints were compared. Results: The titration of antiparkinsonian drugs was associated with a significant decrease in the symptoms of Parkinson’s disease at discharge from the clinic compared with admission (as measured by UPDRS total and subscale scores [all p < 0.001], and, to a lesser extent, by peg insertion and tapping [both p < 0.05]). A significant increase in daily drug costs (an increase of €14.11 per patient for all drugs and €12.36 per patient for antiparkinsonian drugs [both p <0.001]) was also observed. Conclusion: The results demonstrate that the symptoms experienced by patients with Parkinson’s disease improve after performance of antiparkinsonian drug titration within the setting of a specialised Parkinson’s disease clinic. The effect on symptoms was seen most clearly with the UPDRS, although both peg insertion and tapping reflected this improvement to a certain extent. Drug titration resulted in, on average, a doubling of daily drug costs. Future trials are needed to investigate the long-term effects of such a hospital stay on indirect costs associated with treating Parkinson’s disease, and on caregiver burden, and also to compare the efficacy of a Parkinson’s disease clinic with an outpatient setting.

Modulation of disease risk according to a cathepsin D / apolipoprotein E genotype in Parkinson's disease

Summary. Aspartyl protease Cathepsin D (CTSD) has been suggested to play a role in the pathogenesis of sporadic Alzheimers disease (AD) due to interference with protein degradation mechanisms. A C224T (A38V) polymorphism in exon 2 of the CTSD gene is reported to be associated with an increased risk for AD. The partially overlapping pathology between AD and Parkinsons disease (PD) led us to investigate the role of this polymorphism in PD. Using association studies in 457 German PD patients and 340 controls we found no evidence for direct association between the CTSD genotype and PD. However, stratification for the apolipoprotein E (APOE) ε4 allele suggests a protective effect of the CTSD T-allele in PD (OR = 0.24, p = 0.002). Our findings suggest interference of CTSD and APOE polymorphisms in the pathogenesis of PD, in the sense of modulating disease risk.

Lack of mutations in the epsilon-sarcoglycan gene in patients with different subtypes of primary dystonias

Primary dystonias represent a clinically and genetically heterogeneous group of movement disorders. Mutations in the ϵ‐sarcoglycan (SGCE) gene have been found recently to cause myoclonus–dystonia (MD). Considerable clinical variation of SGCE mutation carriers leads to the hypothesis that mutations in the SGCE gene might also be relevant for other subtypes of dystonias. To determine the contribution of mutations in the SGCE gene in patients with different subtypes of dystonias, we analyzed the coding sequence of the SGCE gene in a group of 296 patients with a clinical phenotype of primary dystonia and in 2 patients with a clinical phenotype of myoclonus–dystonia. Patients with mutations in the DYT1 gene were excluded. We could not detect a mutation in the SGCE gene in any of the 298 patients. Our results suggest that mutations in the SGCE gene cannot be held responsible for other subtypes of primary dystonia.

Mutation at the SCA17 locus is not a common cause of primary dystonia.

Abstract.Spinocerebellar ataxia type 17 (SCA17) is a dominant progressive neurodegenerative disorder, caused by a triplet repeat expansion within the TATA-binding protein. As well as ataxia and dementia, Parkinsonism and dystonia are common in SCA17. In some pedigrees focal dystonia in the absence of ataxia has been described as a main clinical feature. To evaluate the relevance of SCA17 mutations for primary dystonia, we examined the TBP repeat expansion in a series of 288 patients with different subtypes of primary torsion dystonia. We did not find any repeat sizes in the pathogenic range. We conclude that the SCA17 repeat expansion is not a common cause of familial and sporadic dystonia.