The early-onset torsion dystonia gene (DYT1) encodes an ATP-binding protein.

Early-onset torsion dystonia is a movement disorder, characterized by twisting muscle contractures, that begins in childhood. Symptoms are believed to result from altered neuronal communication in the basal ganglia. This study identifies the DYT1 gene on human chromosome 9q34 as being responsible for this dominant disease. Almost all cases of early-onset dystonia have a unique 3-bp deletion that appears to have arisen idependently in different ethnic populations. This deletion results in loss of one of a pair of glutamic-acid residues in a conserved region of a novel ATP-binding protein, termed torsinA. This protein has homologues in nematode, rat, mouse and humans, with some resemblance to the family of heat-shock proteins and Clp proteases.

Expression profiling in peripheral blood reveals signature for penetrance in DYT1 dystonia.

DYT1 dystonia is an autosomal-dominantly inherited movement disorder, which is usually caused by a GAG deletion in the TOR1A gene. Due to the reduced penetrance of approximately 30-40%, the determination of the mutation in a subject is of limited use with regard to actual manifestation of symptoms. In the present study, we used Affymetrix oligonucleotide microarrays to analyze global gene expression in blood samples of 15 manifesting and 15 non-manifesting mutation carriers in order to identify a susceptibility profile beyond the GAG deletion which is associated with the manifestation of symptoms in DYT1 dystonia. We identified a genetic signature which distinguished between asymptomatic mutation carriers and symptomatic DYT1 patients with 86.7% sensitivity and 100% specificity. This genetic signature could correctly predict the disease state in an independent test set with a sensitivity of 87.5% and a specificity of 85.7%. Conclusively, this genetic signature might provide a possibility to distinguish DYT1 patients from asymptomatic mutation carriers.

Human gene for torsion dystonia located on chromosome 9q32-q34.

Torsion dystonia is a movement disorder of unknown etiology characterized by loss of control of voluntary movements appearing as sustained muscle contractions and/or abnormal postures. Dystonic movements can be caused by lesions in the basal ganglia, drugs, or gene defects. Several hereditary forms have been described, most of which have autosomal dominant transmission with variable expressivity. In the Ashkenazi Jewish population the defective gene frequency is about 1/10,000. Here, linkage analysis using polymorphic DNA and protein markers has been used to locate a gene responsible for susceptibility to dystonia in a large, non-Jewish kinship. Affected members of this family have a clinical syndrome similar to that found in the Jewish population. This dystonia gene (ITD1) shows tight linkage with the gene encoding gelsolin, an actin binding protein, and appears by multipoint linkage analysis to lie in the q32-q34 region of chromosome 9 between ABO and D9S26, a region that also contains the locus for dopamine-beta-hydroxylase.

Delayed-onset cerebellar syndrome.

BACKGROUND: Delayed-onset involuntary movements, including dystonia and myoclonus, have been reported after stroke or head trauma. Moreover, there have been reports of delayed-onset isolated intention tremor and, in several of these cases, gait ataxia. OBJECTIVE: To further define the clinical features of a delayed-onset cerebellar syndrome. DESIGN: Subjects with cerebellar tremor and either head trauma or stroke were identified using a computerized database, providing detailed demographic and clinical information of 4002 patients with involuntary movements other than Parkinson's disease seen at our center between 1983 and 1995. Medical records and videotaped neurological examinations were retrospectively reviewed. SETTING: The Center for Parkinson's Disease and Other Movement Disorders at Columbia-Presbyterian Medical Center, New York, NY. PATIENTS: Five patients with delayed-onset cerebellar syndromes. RESULTS: Five patients with stroke or head trauma developed a cerebellar syndrome 3 weeks to 2 years after the initial insult. The syndrome, characterized by intention tremor, ataxic dysarthria, nystagmus, dysmetria, dysdiadochokinesis, and gait ataxia, was progressive in at least one patient. In four patients, lesions were present on neuroimaging in the thalamus or brain stem (especially in the midbrain). CONCLUSIONS: A delayed-onset cerebellar syndrome may follow head trauma or stroke. The syndrome is sometimes progressive and often disabling. The delayed onset implies that the syndrome is not caused by the initial lesion itself but may be caused by development of post-synaptic supersensitivity or secondary reorganization of involved pathways.

Use of intrathecal baclofen in the treatment of patients with dystonia.

BACKGROUND: Continuous infusion of intrathecal (IT) baclofen is a highly effective standard therapy for severe spasticity of spinal origin. By contrast, there is limited clinical experience regarding the use of IT baclofen in treating patients with dystonia, and little is known regarding the indications for treatment, efficacy, and safety of IT baclofen in this disorder. OBJECTIVE: To study retrospectively the effects of IT baclofen in treating 25 patients with severe segmental or generalized dystonia. SETTING: Neurological Institute, Columbia-Presbyterian Medical Center, New York, NY. PATIENTS: Twenty-five patients with severe segmental or generalized dystonia that was refractory to oral medications underwent IT baclofen test dosing. In addition to dystonia, 17 patients had spasticity or painful spasms. Thirteen of 25 patients responded to the test doses of IT baclofen, according to unblinded neurological assessments that included the patient's subjective report; all 13 underwent implantation of a pump for continuous IT baclofen infusion. RESULTS: In contrast to reports of patients with spasticity of spinal origin, those with dystonia in the present series had a lower response rate to bolus IT baclofen doses and a smaller degree of clinical improvement. For 10 of the 13 responders to the test doses of IT baclofen, dystonia rating scale scores of videotaped examinations by blinded observers detected no significant change (P < .07) in severity of dystonia. Retrospective data from 11 of 13 patients with implantable pumps, followed up for a mean interval of 21 months after pump insertion, showed continuing efficacy in 6 individuals (55%), based on a determination of patient satisfaction; however, only 3 patients (27%) reported a sustained improvement in functional capacity. Five (38%) of the 13 patients with implantable pumps experienced severe complications that required hospitalization. CONCLUSIONS: Despite recent reports that have described the benefit in small numbers of patients with dystonia, we concluded that the role of IT baclofen in treating severe dystonia remains uncertain. Intrathecal baclofen may be more effective when dystonia is associated with spasticity or pain. In the present series, we detected no significant difference in the response to IT baclofen in patients with or without spasticity or pain, perhaps owing to the small sample size.

The clinical manifestations of pontine hemorrhage.

The survival rate was 40% in 10 patients suffering hemorrhage into the pons who were admitted to an acute care facility. This rate is higher than previously reported. In addition to the "classic" pontine hematoma syndrome characterized by coma, quadriparesis, and eventual demise, two more benign syndromes arising from hemorrhage confined to one side of the pons were also recognized. In one of these hemipontine syndromes, hematoma involved both the basis pontis and tegmentum and was associated with hemiparesis, brainstem signs, and preserved consciousness. In the other, hemorrhage was confined to the tegmentum and was associated with gaze paresis, motor sparing, and preserved consciousness. All patients suffering hemipontine hemorrhage survived. An impressive degree of functional recovery occurred in these survivors.

Rapid-onset dystonia-parkinsonism in a second family.

Rapid-onset dystonia-parkinsonism (RDP), first described in a large Midwestern family, is now reported in a second, apparently unrelated, family in which four individuals have this same syndrome. All four developed sudden onset of dysarthria, dysphagia, severe dystonic spasms, bradykinesia, and postural instability over less than 1 hour to a few days. Three of the four had stable limb dystonia for several years preceding the onset of combined dystonia-parkinsonism. Treatment with levodopa/carbidopa provided little benefit. We propose diagnostic criteria for RDP and further define the spectrum of this unusual disease.

Genetic linkage analysis in primary torsion dystonia.

We studied five families, each containing two siblings affected with torsion dystonia and having phenotypically normal parents, for linkage of dystonia to 18 marker systems, including HLA. Analysis assumed an autosomal recessive mode of inheritance. Linkage was not found. Two markers, HLA and MN, were excluded from tight linkage, and evidence against tight linkage to ABO, Rh, GC, and GLO was obtained.

Validity and reliability of a rating scale for the primary torsion dystonias.

For quantitative assessment of the primary torsion dystonias, a rating scale is proposed that has two sections--a Movement Scale, based on examination, and a Disability Scale, based on the patient's statements about seven activities of daily living. We assessed the validity of the Movement Scale by comparing scores with a ranking of patients according to dystonia severity and with ratings of the patients on the Disability Scale. In addition, we assessed the inter-and intra-rater reliability of the scale by comparing independent scorings of patients by four examiners and by comparing scorings by the same examiners performed at different times. We found that the Movement Scale was a valid and reliable indicator of the severity of primary torsion dystonia.

Delayed-onset dystonia due to perinatal or early childhood asphyxia.

We report 10 patients with delayed-onset dystonia associated with perinatal asphyxia and 2 associated with asphyxia in childhood. In the perinatal group, the mean age of onset was 12.9 years. Among these patients, dystonia continued to progress for a mean of 7 years, and as long as 28 years. These patients had moderate motor disability; none was wheelchair-bound, and thus their prognosis was better than that of the childhood-onset idiopathic torsion dystonias. The most frequently beneficial drugs were anticholinergics. Since some of these patients closely resembled cases of idiopathic torsion dystonia, the prior occurrence of asphyxia should be used as a criterion of exclusion for that diagnosis.

Diagnostic criteria for dystonia in DYT1 families.

Family studies of primary torsion dystonia have used the diagnostic categories of definite, probable, and possible dystonia for gene mapping and identification, but the validity of this hierarchical classification is not known. The authors assessed 147 DYT1 GAG deletion carriers and 113 blood-related noncarriers from 43 families. Only the category of definite dystonia was 100% specific. Probable dystonia, but not possible, was increased in carriers compared with noncarriers. The authors recommend that only those with definite signs of dystonia be considered affected in linkage and other genetic studies.

Evaluation of 50 probands with early-onset Parkinson's disease for Parkin mutations.

BACKGROUND: Early onset PD has been associated with different mutations in the Parkin gene, including exon deletions and duplications. METHODS: The authors performed an extensive mutational analysis on 50 probands with onset of PD at younger than 50 years of age. Thirteen probands were ascertained from a registry of familial PD and 37 probands by age at onset at younger than 50 years, blind to family history. Mutational analysis was undertaken on the probands and available family members and included conventional techniques (single strand conformation polymorphism analysis and sequencing) and a newly developed method of quantitative duplex PCR to detect alterations of gene dosage (exon deletions and duplications) in PARKIN: RESULTS: Using this new technique, the authors detected eight alterations of gene dosage in the probands, whereas 12 mutations were found by conventional methods among the probands and another different mutation in an affected family member. In total, the authors identified compound heterozygous mutations in 14%, heterozygous mutations in 12%, and no Parkin mutation in 74% of the 50 probands. We expanded the occurrence of Parkin mutations to another ethnic group (African-American). CONCLUSION: The authors systematically screened all 12 Parkin exons by quantitative PCR and conventional methods in 50 probands. Eight mutations were newly reported, 2 of which are localized in exon 1, and 38% of the mutations were gene dosage alterations. These results underline the need to screen all exons and to undertake gene dosage studies. Furthermore, this study reveals a frequency of heterozygous mutation carriers that may signify a unique mode of inheritance and expression of the Parkin gene.

Clinical findings of a myoclonus-dystonia family with two distinct mutations.

Myoclonus-dystonia has recently been associated with mutations in the epsilon-sarcoglycan gene (SCGE) on 7q21. Previously, the authors reported a patient with myoclonus-dystonia and an 18-bp deletion in the DYT1 gene on 9q34. The authors have now re-evaluated the patient harboring this deletion for mutations in the SGCE gene and identified a missense change. In the current study, the authors describe the clinical details of this family carrying mutations in two different dystonia genes. Further analysis of these mutations separately and together in cell culture and in animal models should clarify their functional consequences.

Secondary dystonia and the DYTI gene.

Early-onset (< 28 years) primary dystonia in most Ashkenazi Jews is due to a single founder mutation in the DYT1 gene on chromosome 9q34, as determined by very strong linkage disequilibrium with a haplotype of 9q34 alleles at surrounding marker loci. The role of this mutation in individuals with secondary causes for dystonia has never been tested, although environmental insults, such as neuroleptic exposure or perinatal asphyxia, are proposed to precipitate dystonia in genetically predisposed individuals. We assessed 9q34 haplotypes in 40 Ashkenazi patients with secondary dystonia; 25 had early onset of symptoms, including 15 with exposure to neuroleptic medication or perinatal asphyxia. Of the 25 patients with early onset, 9 were considered phenocopies of DYT1 having normal examinations except for dystonia, normal radiographic and other laboratory studies, and onset in a limb or the neck. Only one individual whose dystonia developed in the setting of a measles infection carried the associated haplotype. Our findings indicate that clinical diagnostic criteria that include historical information to detect tardive dystonia and perinatal asphyxia discriminate primary dystonia due to the DYT1 founder mutation. We found no evidence that the DYT1 founder mutation contributes to secondary dystonia.

A study of idiopathic torsion dystonia in a non-Jewish family: evidence for genetic heterogeneity.

A gene (DYT1) for idiopathic torsion dystonia (ITD) was mapped to chromosome 9q34 in non-Jewish and Jewish families; the dystonia in these families usually began in childhood, with the limb muscles affected first. The role of the DYT1 gene in adult-onset and cervical- or cranial-onset ITD is unknown. We examined 53 individuals from four generations of a non-Jewish North American family with adult-onset ITD. There were seven affected family members, with a mean age at onset of 28.4 years (range, 7 to 50 years). In six of the seven, the neck was affected first. All seven developed cervical dystonia, and dysarthria or dysphonia occurred in five. Linkage data excluded the region containing the DYT1 locus, indicating that DYT1 was not responsible for ITD in this family. This study provides evidence that a gene other than DYT1 is responsible for some cases of adult cervical-onset dystonia.

The DYT1 phenotype and guidelines for diagnostic testing.

OBJECTIVE: To develop diagnostic testing guidelines for the DYT1 GAG deletion in the Ashkenazi Jewish (AJ) and non-Jewish (NJ) primary torsion dystonia (PTD) populations and to determine the range of dystonic features in affected DYT1 deletion carriers. METHODS: The authors screened 267 individuals with PTD; 170 were clinically ascertained for diagnosis and treatment, 87 were affected family members ascertained for genetic studies, and 10 were clinically and genetically ascertained and included in both groups. We used published primers and PCR amplification across the critical DYT1 region to determine GAG deletion status. Features of dystonia in clinically ascertained (affected) DYT1 GAG deletion carriers and noncarriers were compared to determine a classification scheme that optimized prediction of carriers. The authors assessed the range of clinical features in the genetically ascertained (affected) DYT1 deletion carriers and tested for differences between AJ and NJ patients. RESULTS: The optimal algorithm for classification of clinically ascertained carriers was disease onset before age 24 years in a limb (misclassification, 16.5%; sensitivity, 95%; specificity, 80%). Although application of this classification scheme provided good separation in the AJ group (sensitivity, 96%; specificity, 88%), as well as in the group overall, it was less specific in discriminating NJ carriers from noncarriers (sensitivity, 94%; specificity, 69%). Using age 26 years as the cut-off and any site at onset gave a sensitivity of 100%, but specificity decreased to 54% (63% in AJ and 43% in NJ). Among genetically ascertained carriers, onset up to age 44 years occurred, although the great majority displayed early limb onset. There were no significant differences between AJ and NJ genetically ascertained carriers, except that a higher proportion of NJ carriers had onset in a leg, rather than an arm, and widespread disease. CONCLUSIONS: Diagnostic DYT1 testing in conjunction with genetic counseling is recommended for patients with PTD with onset before age 26 years, as this single criterion detected 100% of clinically ascertained carriers, with specificities of 43% to 63%. Testing patients with onset after age 26 years also may be warranted in those having an affected relative with early onset, as the only carriers we observed with onset at age 26 or later were genetically ascertained relatives of individuals whose symptoms started before age 26 years.

Myoclonus dystonia: possible association with obsessive-compulsive disorder and alcohol dependence.

BACKGROUND: Inherited myoclonus-dystonia (M-D) is a disorder that is characterized primarily by myoclonic jerks and is often accompanied by dystonia. In addition to motor features, psychiatric disease is reported in some families. METHODS: To determine whether the same genetic etiology underlies both neurologic and psychiatric signs, the authors studied psychiatric symptoms in nonmanifesting carriers (NMC), noncarriers (NC), and manifesting carriers (MC) in three families demonstrating linkage of M-D to the 7q21 locus. Interviewers administered the computerized version of the Composite International Diagnostic Interview. Algorithms for the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition diagnosis of obsessive-compulsive disorder (OCD), generalized anxiety disorder, major affective disorder, alcohol abuse, alcohol dependence, drug abuse, and drug dependence were used. Rates of disorders among the MC, NMC, and NC were compared. RESULTS: Of 55 participating individuals, 16 were MC, 11 were NMC, and 28 were NC. The rate of OCD was greater in carriers (5/27) compared with NC (0/28) (p = 0.023). It was also greater in the symptomatic gene carriers (4/16) compared with the asymptomatic group (1/11) (p = 0.022). Alcohol dependence was increased in the symptomatic carriers (7/16) (p = 0.027), but not in the carrier group overall (7/27). CONCLUSION: OCD may be associated with the DYT11 M-D gene; however, a larger sample is necessary to confirm this finding. Alcohol dependence is highly associated with expressing symptoms of M-D. This may be explained by self-medication with alcohol to improve motor symptoms of M-D.

Phenotypic features of myoclonus-dystonia in three kindreds.

BACKGROUND: Myoclonus-dystonia (M-D) is a movement disorder with involuntary jerks and dystonic contractions. Autosomal dominant alcohol-responsive M-D is associated with mutations in the epsilon-sarcoglycan gene (SGCE) (six families) and with a missense change in the D2 dopamine receptor (DRD2)gene (one family). OBJECTIVE: To investigate the clinical phenotype associated with M-D including motor symptoms, psychiatric disorders, and neuropsychological deficits. METHODS: Fifty individuals in three M-D families were evaluated and a standardized neurologic examination and DNA analysis were performed. Psychiatric profiles were established with the Diagnostic Interviews for Genetic Studies (DIGS) and the Yale-Brown Obsessive-Compulsive Scale (YBOCS). Cognition was evaluated with standardized neuropsychological tests. RESULTS: Distinct truncating mutations in the SGCE gene were identified in each family. Additionally, a missense alteration in the DRD2 gene was previously found in one family. Motor expression was variable, with onset of myoclonus or dystonia or both affecting the upper body and progression to myoclonus and dystonia in most cases. Psychiatric profiles revealed depression, obsessive-compulsive disorder, substance abuse, anxiety/panic/phobic disorders, and psychosis in two families, and depression only in the third family. Averaged scores from cognitive testing showed impaired verbal learning and memory in one family, impaired memory in the second family, and no cognitive deficits in the third family. CONCLUSIONS: Cognitive deficits may be associated with M-D. Psychiatric abnormalities correlate with the motor symptoms in affected individuals. Assessment of additional M-D families with known mutations is needed to determine whether these are characteristic phenotypic manifestations of M-D.

Dystonia update.

Dystonia is a syndrome of sustained muscle spasms of presumed central nervous system origin. Recent advances in molecular biology have permitted clearer understanding of the genetics of various forms of dystonia and suggest pathophysiological deficits at the origin of the clinical signs. Treatment has involved centrally-acting drugs, specifically the anticholinergic medications, as well as peripherally acting agents that block neuromuscular transmission (botulinum toxin). Some forms of dystonia are particularly responsive to levodopa. A systematic approach to the diagnostic and treatment evaluation of dystonic patients permits optimal care for long-term management.

Paroxysmal non-kinesigenic dystonia.

We reviewed the records of all patients with paroxysmal nonkinesigenic dystonia seen at Dystonia Clinical Research Center. Of the total of 25 patients, three subgroups based on etiology were discerned: primary sporadic (7 patients), psychogenic (11 patients), and symptomatic (7 patients). There were no patients with primary paroxysmal dystonia with a family history of a similar disorder. Although many of the characteristics of our sporadic cases were similar to those of familial paroxysmal dystonia reported in the literature, numerous differences were noted including adult onset, female predominance, and variability in the duration and frequency of attacks. In certain cases an overlap with PKC was found. Clonazepam and acetazolamide were effective in several patients.