A novel clinical syndrome revealing a deficiency of the muscarinic M3 receptor.

OBJECTIVES: No clinical disorders have been caused by dysfunction of any of the 5 subtypes (M1-M5) of muscarinic receptors. We present a patient with a novel clinical syndrome that we suggest results from a deficiency of the muscarinic M3 receptor. METHODS: We conducted a comprehensive workup of autonomic function. The patient's disorder was compared to the phenotypic features of male M3 knockout mice. M3 protein quantity was assessed by Western blot and radioligand binding in peripheral blood lymphocytes. Tests for autoantibodies and genetic abnormalities were performed. RESULTS: The disease pattern was characterized by disturbances in micturition, pupil constriction, body weight, and sudomotor function, with normal accommodation, gastrointestinal motility, salivation, and lacrimation, similar to features of male M3 knockout mice. M3 protein quantity was reduced. Genetic tests were unrevealing, but unspecific antinuclear antibodies were present. CONCLUSIONS: The presented clinical syndrome suggests a deficiency of the muscarinic M3 receptor. These results and future evaluation of patients with autonomic deficits may provide insights into the site and functional role of the muscarinic M3 receptor in humans.

EFNS guidelines on diagnosis and treatment of primary dystonias.

OBJECTIVES: to provide a revised version of earlier guidelines published in 2006. BACKGROUND: primary dystonias are chronic and often disabling conditions with a widespread spectrum mainly in young people. DIAGNOSIS: primary dystonias are classified as pure dystonia, dystonia plus or paroxysmal dystonia syndromes. Assessment should be performed using a validated rating scale for dystonia. Genetic testing may be performed after establishing the clinical diagnosis. DYT1 testing is recommended for patients with primary dystonia with limb onset before age 30, and in those with an affected relative with early-onset dystonia. DYT6 testing is recommended in early-onset or familial cases with cranio-cervical dystonia or after exclusion of DYT1. Individuals with early-onset myoclonus should be tested for mutations in the DYT11 gene. If direct sequencing of the DYT11 gene is negative, additional gene dosage is required to improve the proportion of mutations detected. A levodopa trial is warranted in every patient with early-onset primary dystonia without an alternative diagnosis. In patients with idiopathic dystonia, neurophysiological tests can help with describing the pathophysiological mechanisms underlying the disorder. TREATMENT: botulinum toxin (BoNT) type A is the first-line treatment for primary cranial (excluding oromandibular) or cervical dystonia; it is also effective on writing dystonia. BoNT/B is not inferior to BoNT/A in cervical dystonia. Pallidal deep brain stimulation (DBS) is considered a good option, particularly for primary generalized or cervical dystonia, after medication or BoNT have failed. DBS is less effective in secondary dystonia. This treatment requires a specialized expertise and a multidisciplinary team.

Dystonia-plus syndromes.

Dystonia-plus syndromes represent a heterogeneous group of diseases, where dystonia is accompanied by other neurological features and gene mutations can be detected frequently. Symptomatic dystonias and complex neurodegenerative diseases with dystonia as part of the clinical presentation are excluded from this category. At present, the following disorders are categorized as dystonia-plus syndromes: Dopa-responsive dystonia (DRD) is a mostly pediatric-onset, neurometabolic disorder with two different modes of inheritance: in its autosomal-dominant form, heterozygous mutations of GTP-cyclohydrolase I (GCH1, DYT5) cause DRD with reduced penetrance and excellent and lasting response to levodopa. Autosomal-recessive (AR) forms of DRD are caused by homozygous or compound heterozygous mutations of the tyrosine hydroxylase (TH) or the sepiapterin reductase (SPR) gene. In AR-DRD, the phenotype is generally more severe including cognitive deficits and developmental delay. Diagnosis can be confirmed by analysis of CSF pterine metabolites. Alternatively, comprehensive genetic testing yields causative mutations in up to 80% of patients. Myoclonus-dystonia (M-D) is caused by heterozygous mutations of the epsilon-sarcoglycan gene (SGCE). Dystonia is generally only mild to moderate, and 'lightning-like' myoclonic jerks occur rarely at rest and can be triggered by complex motor tasks like writing and drawing. Both features together with an age at onset below 25 years strongly predict SGCE mutation in M-D and differentiate this genetic disease from other 'jerky' dystonias. The combination of dystonia and parkinsonism can only be rarely observed in non-degenerative syndromes. Besides DRD, two additional syndromes have been classified. Rapid-onset dystonia-parkinsonism (RPD, DYT12) is a rare disorder with an abrupt onset of symptoms over minutes to days, prominent bulbar involvement and parkinsonism with a lack of response to levodopa. Patients with this rare phenotype should be screened for mutation in the Na(+)/K(+) ATPase alpha3-subunit (ATP1A3) gene, even if family history is negative. Recently, a novel form of dystonia-parkinsonism (DYT16) has been found to be linked to mutations in the PRKRA gene, whose relation to basal ganglia disorders is yet unknown .

No muscle involvement in myoclonus-dystonia caused by epsilon-sarcoglycan gene mutations.

Mutations in the epsilon-sarcoglycan gene (SGCE) can cause autosomal dominant inherited myoclonus-dystonia (M-D). Defects in other sarcoglycans; alpha-, beta-, gamma-, and delta can cause autosomal recessive inherited limb girdle muscular dystrophies. epsilon- and alpha-sarcoglycans are very homologous and may substitute for one-another in different tissues. We therefore investigated whether mutations in SGCE also cause abnormalities of skeletal and myocardial muscle. Six patients with clinically and genetically verified M-D and no signs of limb-girdle muscular dystrophy were included. Skeletal muscle biopsies were obtained from all patients, and endomyocardial muscle biopsy from one of the patients. Morphological and immunohistological investigations were performed and compared with controls. Histological and immunohistological investigations of muscle and clinical assessment of muscle strength and mass showed no difference between M-D patients and controls. Our findings indicate that patients with M-D have no signs or symptoms of muscle disease. This suggests a different role of the sarcoglycan complex epsilonbetagammadelta versus alphabetagammadelta complex in humans, as earlier suggested in rodents.

Strong genetic evidence for association of TOR1A/TOR1B with idiopathic dystonia.

Recently, association of a TOR1A(DYT1)/TOR1B risk haplotype with common forms of idiopathic dystonia has been reported in the Icelandic population. Here we report a strong association of two single nucleotide polymorphisms within or in close proximity to the TOR1A 3'UTR, with the lowest p value being 0.000008, in a larger cohort of German and Austrian patients with predominantly focal sporadic dystonia.

Mutations in the CLCN2 gene are a rare cause of idiopathic generalized epilepsy syndromes.

Mutations in the chloride channel gene CLCN2 have been reported in families with generalized and focal epilepsy syndromes. To evaluate the contribution of mutations in the CLCN2 gene to the etiology of epilepsies in our population, we screened 96 patients with different epilepsy syndromes and a putative genetic background. No definite mutations were found in our study population. We conclude that mutations in the CLCN2 gene are only a rare cause of idiopathic generalized epilepsy.

Familial dopa-responsive cervical dystonia.

The authors present four cases from two unrelated families with young-onset predominant cervical dystonia with a dramatic sustained response to levodopa. Onset age was 12 years (range 9 to 15). Additional symptoms included postural hand tremor and laryngeal dystonia. Genetic testing for GTP cyclohydrolase I, tyrosine hydroxylase, and sepiapterin reductase was negative. These cases may represent new forms of dopa-responsive dystonia. Levodopa is advisable in all patients with young-onset cervical dystonia.

A novel TITF-1 mutation causes benign hereditary chorea with response to levodopa.

Presented is a pedigree with infancy-onset benign hereditary chorea (BHC) caused by a novel nonsense mutation in exon 3 (523G-->T, E175X) of the TITF-1 (Nkx2.1) gene. Four confirmed mutation carriers showed the typical movement disorder of BHC and congenital hypothyroidism. Surprisingly, treatment with levodopa improved gait dramatically and reduced chorea in two patients. Dopaminergic drugs should be considered a useful therapeutic option in BHC.

The role of alpha-synuclein gene multiplications in early-onset Parkinson's disease and dementia with Lewy bodies.

BACKGROUND: A triplication of the alpha-synuclein gene was found to cause autosomal dominant Lewy body disease in two distinct families. METHOD: We searched for alterations of alpha-synuclein gene dosage and analysed the entire coding region for point mutations in 54 dementia with Lewy body disease (DLB) and in 103 young onset Parkinson's disease (PD) patients from Central Europe. RESULTS: We could not detect any quantitative alterations in the gene dosage of alpha-synuclein. Mutational screening of the entire coding region of alpha-synuclein revealed only one silent mutation V3V (adenine9guanine) in one case. CONCLUSIONS: Thus, this phenomenon appears not to be a major cause in the pathogenesis of sporadic DLB and young onset PD in this European population.

Candidate gene studies in focal dystonia.

BACKGROUND: Genetic susceptibility factors for focal idiopathic torsion dystonia (F-ITD) are not established. Mutations in the DYT1 gene can cause focal dystonia, and an association with a polymorphism in the D5 receptor gene (DRD5) has been reported but not confirmed. OBJECTIVE: To investigate a possible role of DYT1 polymorphisms, a CA repeat in the D5 receptor gene (DRD5), the human leukocyte antigen (HLA)-DRB locus, and four polymorphisms in the homocysteine metabolism in the pathogenesis of F-ITD. METHODS: Initially, 100 German patients and 100 matched control subjects were investigated. A second French population with 121 F-ITD patients and matched control subjects was also studied. RESULTS: Two polymorphisms of the beta-cystathionine synthase gene were associated with F-ITD in the German population, but this finding was not replicated in a second independent F-ITD patient and control group of French origin. None of the other investigated polymorphisms was associated with F-ITD. The authors failed to confirm a previously reported association with a polymorphism in DRD5. CONCLUSION: No evidence for an involvement of DYT1, DRD5, HLA-DRB, or polymorphisms in the homocysteine pathway in the pathogenesis of F-ITD was found.

Mutations in the gene encoding epsilon-sarcoglycan cause myoclonus-dystonia syndrome.

The dystonias are a common clinically and genetically heterogeneous group of movement disorders. More than ten loci for inherited forms of dystonia have been mapped, but only three mutated genes have been identified so far. These are DYT1, encoding torsin A and mutant in the early-onset generalized form, GCH1 (formerly known as DYT5), encoding GTP-cyclohydrolase I and mutant in dominant dopa-responsive dystonia, and TH, encoding tyrosine hydroxylase and mutant in the recessive form of the disease. Myoclonus-dystonia syndrome (MDS; DYT11) is an autosomal dominant disorder characterized by bilateral, alcohol-sensitive myoclonic jerks involving mainly the arms and axial muscles. Dystonia, usually torticollis and/or writer's cramp, occurs in most but not all affected patients and may occasionally be the only symptom of the disease. In addition, patients often show prominent psychiatric abnormalities, including panic attacks and obsessive-compulsive behavior. In most MDS families, the disease is linked to a locus on chromosome 7q21 (refs. 11-13). Using a positional cloning approach, we have identified five different heterozygous loss-of-function mutations in the gene for epsilon-sarcoglycan (SGCE), which we mapped to a refined critical region of about 3.2 Mb. SGCE is expressed in all brain regions examined. Pedigree analysis shows a marked difference in penetrance depending on the parental origin of the disease allele. This is indicative of a maternal imprinting mechanism, which has been demonstrated in the mouse epsilon-sarcoglycan gene.

Inherited Myoclonus-dystonia syndrome: narrowing the 7q21-q31 locus in German families.

Genetic studies were performed in four German families with autosomal dominant myodonus-dystonia syndrome. Mutations in the D2 dopamine receptor gene, which have been implicated in this disorder, were excluded in all four families by linkage analysis and direct sequencing. All four families supported linkage to the second reported locus on chromosome 7q21 with a combined maximum multipoint lod score of 5.99. The observation of key recombinations in one family refined the disease locus to a 7.2 cM region flanked by the markers D7S652 and D7S2480.

Subunit expression of the cardiac L-type calcium channel is differentially regulated in diastolic heart failure of the cardiac allograft.

BACKGROUND: Left ventricular diastolic dysfunction is a major cause of cardiac allograft failure. Multimeric L-type calcium channels (alpha1-, alpha2/delta-, and beta-subunits) are essential for excitation/contraction coupling in the heart. Their gene expression was studied in allografts that developed diastolic heart failure. METHODS AND RESULTS: mRNA levels of calcium channel subunits were measured by competitive reverse transcriptase-polymerase chain reaction in microbiopsy samples from the interventricular septum. Size and tissue variabilities between biopsy samples were assessed by determination of cardiac calsequestrin mRNA levels. In the cardiac allografts studied, mRNA levels in microbiopsy samples were considered to represent left ventricular gene expression, because septal and left ventricular gene expression in Northern blots was equivalent, and left ventricles contracted homogeneously. Biopsy samples (n=72) were taken from allografts with normal left ventricular end-diastolic pressure (LVEDP; 8 to 13 mm Hg; n=30), moderately elevated LVEDP (14 to 18 mm Hg; n=26), and elevated LVEDP (19 to 28 mm Hg; n=16). Increased LVEDP was related to slowed diastolic relaxation determined by the time constant tau (r2=0.86), whereas systolic performance (dP/dt; ejection fraction) was preserved. With increasing LVEDP, mRNA levels of the pore-forming alpha1c-subunit (n=15) and of the regulatory alpha2/delta-subunit (n=17) remained unchanged but decreased exponentially (r2=-0.83) for the regulatory beta-subunit (n=40). Compared with cardiac allografts with normal LVEDP (n=15), beta-subunit mRNA level was reduced by 75% at elevated LVEDP (n=9; P=0.012). In an explanted, diastolically failing cardiac allograft, beta-subunit expression was reduced correspondingly by 72% and 76% on the mRNA level in septal and left ventricular myocardium and by 80% on the protein level. CONCLUSIONS: The downregulated expression of the calcium channel beta-subunit might contribute to altered calcium handling in diastolically failing cardiac allografts.

Physician-assisted suicide in psychiatry: developments in The Netherlands.

Physician-assisted suicide can now be officially and legally carried out for psychiatric patients in The Netherlands who request it, provided that criteria are met. The authors describe two recent cases of psychiatric patients whose suicides were assisted by their psychiatrist. They critically examine the guidelines for physician-assisted suicide in psychiatry. The criteria address the decision of the patient to be assisted with suicide, which must be voluntary and well considered, and the patient's desire to die, which must endure over time. The patient's suffering must be unacceptable, and the disorder incurable. The authors conclude that important aspects of psychiatric practice are not addressed in the guidelines, which were originally developed for use in somatic medicine. The assessment of treatment prognosis in psychiatry is not accurate enough to allow a final decision about incurability. Boundaries of the psychiatric therapeutic relationship are violated in physician-assisted suicide. The therapist's inability to objectively assess the patient's wish to die is overlooked. Because the general public will continue to ask for clarity on the issue of euthanasia and physician-assisted suicide, the authors believe that an open discussion of both ethical and professional issues is the best option.

Competitive RT-PCR for studying gene expression in micro biopsies.

The technique of RT-PCR has become a powerful method for studying gene expression in various species and tissues. Here we present a competitive PCR for quantitative measurement of absolute levels of mRNA molecules for the regulatory alpha 2/delta subunit of the high-voltage-activated dihydropyridine sensitive human cardiac L-type calcium channel. With the method described the dynamic process of cardiac gene expression can be studied in human endomyocardial biopsies in different patient collectives and even in the individual.