ABSTRACT
INTRODUCTION: In previous studies of myasthenia gravis (MG), increased mortality has been reported. The aim of this study was to estimate mortality in patients with acetylcholine receptor antibody-positive (AChR-Ab-seropositive) MG in a nationwide population-based, long-term follow-up study. METHODS: All AChR-Ab-seropositive MG patients, diagnosed between 1985 and 2005, were identified. Defined by age at diagnosis (≤ 50 or >50 years), patients were classified as having early- or late-onset MG. For comparison, 10 non-MG individuals from the general population were matched with each patient. All patients and controls were followed until January 1, 2009. Mortality rates and estimated mortality rate ratios (MRRs) were calculated. RESULTS: Of 702 AChR-Ab-seropositive MG patients, 302 died during follow-up. Overall mortality was higher for patients with MG (MRR = 1.41, range 1.24-1.60). In late-onset women and men, the MRRs were 1.64 (1.36-1.99) and 1.22 (1.02-1.46), respectively. Total MRR was highest during the first 5 years after diagnosis. CONCLUSIONS: MG diagnosis is still associated with increased mortality.
Subject(s)
Myasthenia Gravis/epidemiology , Myasthenia Gravis/mortality , Adolescent , Adult , Aged , Aged, 80 and over , Antibodies/blood , Community Health Planning , Denmark/epidemiology , Female , Follow-Up Studies , Humans , Kaplan-Meier Estimate , Male , Middle Aged , Proportional Hazards Models , Receptors, Cholinergic/immunology , Retrospective Studies , Young AdultABSTRACT
Group A streptococcal (GAS) infections and autoimmunity are associated with the onset of a spectrum of neuropsychiatric disorders in children, with the prototypical disorder being Sydenham chorea (SC). Our aim was to develop an animal model that resembled the behavioral, pharmacological, and immunological abnormalities of SC and other streptococcal-related neuropsychiatric disorders. Male Lewis rats exposed to GAS antigen exhibited motor symptoms (impaired food manipulation and beam walking) and compulsive behavior (increased induced-grooming). These symptoms were alleviated by the D2 blocker haloperidol and the selective serotonin reuptake inhibitor paroxetine, respectively, drugs that are used to treat motor symptoms and compulsions in streptococcal-related neuropsychiatric disorders. Streptococcal exposure resulted in antibody deposition in the striatum, thalamus, and frontal cortex, and concomitant alterations in dopamine and glutamate levels in cortex and basal ganglia, consistent with the known pathophysiology of SC and related neuropsychiatric disorders. Autoantibodies (IgG) of GAS rats reacted with tubulin and caused elevated calcium/calmodulin-dependent protein kinase II signaling in SK-N-SH neuronal cells, as previously found with sera from SC and related neuropsychiatric disorders. Our new animal model translates directly to human disease and led us to discover autoantibodies targeted against dopamine D1 and D2 receptors in the rat model as well as in SC and other streptococcal-related neuropsychiatric disorders.
Subject(s)
Chorea/psychology , Disease Models, Animal , Mental Disorders/psychology , Motor Activity/immunology , Streptococcal Infections/psychology , Streptococcus pyogenes , Adolescent , Animals , Autoantibodies/biosynthesis , Child , Child, Preschool , Chorea/immunology , Chorea/microbiology , Female , Grooming/drug effects , Grooming/physiology , Humans , Male , Mental Disorders/immunology , Mental Disorders/microbiology , Motor Activity/drug effects , Rats , Rats, Inbred Lew , Streptococcal Infections/drug therapy , Streptococcal Infections/immunology , Streptococcus pyogenes/drug effects , Streptococcus pyogenes/immunologyABSTRACT
The incidence of myasthenia gravis (MG) from 1970 through 1999 was studied in an area with 2.3 million inhabitants. The mean annual incidence rate of early-onset MG was constant at 3.5 x 10(-6). In late-onset MG, the rate increased from 4.7 to 20.8 x 10(-6). The two onset types of MG may thus be distinct disorders. The author hypothesized that late-onset nonthymoma anti-acetylcholine receptor antibody-seropositive MG may be provoked by environmental factors.
Subject(s)
Autoantibodies/blood , Myasthenia Gravis/epidemiology , Receptors, Nicotinic/immunology , Age Distribution , Age of Onset , Aged , Aged, 80 and over , Denmark/epidemiology , Female , Humans , Incidence , Male , Middle Aged , Myasthenia Gravis/blood , Myasthenia Gravis/immunology , Neuromuscular Junction/immunology , Neuromuscular Junction/physiopathology , Selection Bias , Sex DistributionABSTRACT
OBJECTIVE: To estimate the incidence of elevated anti-titin antibodies titers and of thymomas in a population of patients with MG using various statistics and associations. METHODS: Extensive epidemiology, systematic measurement of anti-titin antibodies, and histologic assessment of thymomas according to the new World Health Organization classification. RESULTS: The mean annual incidence rate of MG per million population was 8.3. The analogous mean rate of thymomas was 2.0, out of which MG was encountered in about 20%. A thymoma was coexistent in 7% of the patients with MG. The finding of titin autoantibodies and the coexistence of thymomas were both associated with age at the appearance of MG. In patients with MG with a thymoma, the frequency of seropositivity was 68%, whereas acetylcholine receptor (AChR) autoantibodies were detected in all such sera. Titin autoantibody-positive sera were also anti-AChR antibodies positive. Further, all serum samples negative for anti-AChR antibodies were devoid of anti-titin antibodies. Titin autoantibodies were not detected in nonthymoma early-onset MG. CONCLUSION: Apart from MG with a thymoma, the finding of the titin autoantibodies was observed to be an exclusive feature of late-onset MG, the frequency being 55%. No data were found to suggest that patients with MG were more likely to present with thymic tumors than other patients exhibiting thymic neoplasia. In about 80%, such tumors in MG were composed of cortical cells. The concept of the anti-titin antibodies merely as a paraneoplastic marker in MG was not supported by these data.
