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Biomedical subjects

Susan B Bressman

Publications and source records attributed to Susan B Bressman.

13 recordsLinked to original sources

Obsessive-compulsive disorder is not a clinical manifestation of the DYT1 dystonia gene.

Prior studies suggest that obsessive-compulsive symptoms (OCS) and disorder (OCD) are co-morbid with dystonia. We tested if OCS/OCD is a clinical manifestation of the DYT1 dystonia mutation by interviewing members of families with an identified DYT1 mutation, and classifying by manifesting carriers (MC), non-manifesting carriers (NMC), and non-carriers (NC). We found that OCD/OCS are not increased in DYT1 mutation carriers compared with NC, nor is OCD associated with manifesting DYT1 dystonia.

Adult↗

The diagnosis of dystonia.

Dystonia is a movement disorder with many presentations and diverse causes. A systematic approach to dystonia helps to ensure that patients with this disorder receive optimum care. This Review begins with a summary of the clinical features of dystonia, followed by a discussion of other disorders to be considered and excluded before assigning the diagnosis of dystonia. Next, we emphasise the importance of classifying dystonia along several dimensions, and we explain how doing so aids in narrowing the differential diagnosis. The more common forms of dystonia are discussed in detail. Finally, we describe how to apply the clinical information for selection of appropriate laboratory investigations.

Age of Onset↗

The metabolic pathology of dopa-responsive dystonia.

We used [(18)F]-fluorodeoxyglucose and positron emission tomography to determine a discrete cerebral pattern of abnormal glucose utilization in dopa-responsive dystonia. Network analysis demonstrated that dopa-responsive dystonia is associated with a specific pattern of regional metabolic covariation, characterized by increases in the dorsal midbrain, cerebellum, and supplementary motor area, as well as reductions in motor and lateral premotor cortex and in the basal ganglia. This pattern was not expressed in mutation carriers for primary torsion dystonia. Dopa-responsive dystonia has a unique metabolic architecture that differs from other inherited forms of dystonia.

Adult↗

Mutations in the Na+/K+ -ATPase alpha3 gene ATP1A3 are associated with rapid-onset dystonia parkinsonism.

Rapid-onset dystonia-parkinsonism (RDP, DYT12) is a distinctive autosomal-dominant movement disorder with variable expressivity and reduced penetrance characterized by abrupt onset of dystonia, usually accompanied by signs of parkinsonism. The sudden onset of symptoms over hours to a few weeks, often associated with physical or emotional stress, suggests a trigger initiating a nervous system insult resulting in permanent neurologic disability. We report the finding of six missense mutations in the gene for the Na+/K+ -ATPase alpha3 subunit (ATP1A3) in seven unrelated families with RDP. Functional studies and structural analysis of the protein suggest that these mutations impair enzyme activity or stability. This finding implicates the Na+/K+ pump, a crucial protein responsible for the electrochemical gradient across the cell membrane, in dystonia and parkinsonism.

Amino Acid Sequence↗

Distribution, type, and origin of Parkin mutations: review and case studies.

Early-onset Parkinson's disease (PD) has been associated with different mutations in the Parkin gene (PARK2). To study distribution and type of Parkin mutations, we carried out a comprehensive literature review that demonstrated two prominent types of mutations among 379 unrelated mutation carriers: exon rearrangements involving exon 3, 4, or both, and alterations in exons 2 and 7, suggesting mutational hot spots or founders. To elucidate the origin of 14 recurrent Parkin mutations in our samples, we carried out a detailed haplotype analysis at the PARK2 locus. Thirty-eight mutation-positive individuals, available family members, and 62 mutation-negative individuals were genotyped. We determined allele frequencies and linkage disequilibrium (LD) to evaluate the significance of shared haplotypes. We observed no LD between markers at PARK2. Our data support a common founder for the most frequent Parkin point mutation (924C>T; exon 7) and indicate a mutational hot spot as cause of a common small deletion (255/256delA; exon 2). Furthermore, the most frequent Parkin exon deletion (Ex4del) arose independently in 2 of our subjects. However, it also occurred as the result of a founder mutation in 2 cases that shared identical deletion break points. This study provides evidence for both mutational hot spots and founder mutations as a source of recurrent mutations in Parkin, regardless of the mutation type.

Adult↗

A heteroplasmic mitochondrial complex I gene mutation in adult-onset dystonia.

Mitochondrial DNA (mtDNA) mutations can cause rare forms of dystonia, but the role of mtDNA mutations in other types of dystonia is not well understood. We now report identification by sequencing, restriction endonuclease analyses, and clonal analyses of a heteroplasmic missense A to G base pair substitution at nucleotide position 3796 (A3796G) in the gene encoding the ND1 subunit of mitochondrial complex I in a patient with adult-onset dystonia, spasticity, and core-type myopathy. The mutation converts a highly conserved threonine to an alanine. The same mutation subsequently was identified in 2 of 74 additional unrelated adult-onset dystonia patients. A muscle biopsy was obtained from 1 of these 2 subjects and this revealed abnormalities of electron transport chain (ETC) activities. The mutation was absent in 64 subjects with early onset dystonia, 82 normal controls, and 65 subjects with Parkinson's disease or multiple system atrophy. The A3796G mutation previously has been reported in 3 of 226 subjects from mitochondrial haplogroup H. Each of the 3 subjects in our study harboring the A3796G mutation was also from haplogroup H. However, a subgroup analysis of haplogroup H subjects from our study indicates that the A3796G mutation is significantly overrepresented among haplogroup H adult-onset dystonia subjects compared with haplogroup H controls (P<0.01). This difference remains significant even after excluding the index patient (P=0.04). These data suggest that, among haplogroup H subjects, the presence of the A3796G mutation increases the risk of developing adult-onset dystonia.

Adolescent↗

Epsilon-sarcoglycan mutations found in combination with other dystonia gene mutations.

Myoclonus-dystonia is a movement disorder associated with mutations in the epsilon-sarcoglycan gene (SGCE) in most families and in the DRD2 and DYT1 genes in two single families. In both of the latter families, we also found a mutation of SGCE. The molecular mechanisms through which the detected mutations may contribute to myoclonus-dystonia remain to be determined.

Base Sequence↗

Primary dystonia: is abnormal functional brain architecture linked to genotype?

The DYT1 dystonia mutation is associated with an abnormal metabolic brain network characterized by hypermetabolism of the basal ganglia, supplementary motor area, and the cerebellum. In this study, we quantified the activity of this network in carriers of other dystonia mutations to determine whether this functional abnormality is linked to genotype. The findings suggest that the DYT1 metabolic topography is not genotype specific and may be present in carriers of other dystonia mutations.

Adult↗