Carlo Antozzi

Maternally inherited myopathy and cardiomyopathy: association with mutation in mitochondrial DNA tRNALeu(UUR)

Different point mutations of the mitochondrial genome, which all affect the ability of mitochondria to translate their own genes and lead to partial defects of mtDNA-dependent respiratory complexes, are related to distinct clinical mitochondrial disorders. A new maternally inherited disorder, characterised by a combination of adult-onset myopathy and cardiomyopathy, with no clinical involvement of the nervous system, was found in members of a single large pedigree. A heteroplasmic new mutation was identified in the mtDNA gene specifying tRNA(Leu)(UUR). This mutation segregated specifically with the disorder, and there were significant correlations between the proportion of the mtDNA that was of the mutant form and the activities (normalised for citrate synthase activity) of the two mtDNA-dependent respiratory enzymes (complex I, r = -0.71, p less than 0.005: complex IV r = -0.77, p less than 0.005) and the maximum oxygen consumption (r = -0.82, p less than 0.005), a physiological index of aerobic metabolism. These findings strongly suggest that the tRNA(Leu)(UUR) mutation is the genetic cause of this disorder, and that lesions of mtDNA should be considered in the differential diagnosis of the hereditary cardiomyopathies.

Experience with immunomodulatory treatments in Rasmussen’s encephalitis

The authors investigated immunomodulatory treatments in 15 patients with Rasmussen encephalitis (RE) (14 with childhood and one with adolescent onset RE). Positive time-limited responses were obtained in 11 patients using variable combinations of corticosteroids, apheresis, and high-dose IV immunoglobulins. Although surgical exclusion of the affected hemisphere is the only treatment that halts disease progression, immunomodulation can be considered when early surgery is not feasible, in late-onset patients with slower disease progression, and in the few cases of bilateral disease.

Epileptic phenotypes associated with mitochondrial disorders

Objective: To define the clinical and EEG features of the epileptic syndromes occurring in adult and infantile mitochondrial encephalopathies (ME). Methods: Thirty-one patients with recurrent and apparently unprovoked seizures associated with primary ME were included in the study. Diagnosis of ME was based on the recognition of a morphologic, biochemical, or molecular defect. Results: Epileptic seizures were the first recognized symptom in 53% of the patients. Many adults (43%) and most infants (70%) had nontypical ME phenotypes. Partial seizures, mainly with elementary motor symptoms, and focal or multifocal EEG epileptiform activities characterized the epileptic presentation in 71% of the patients. Generalized myoclonic seizures were an early and consistent symptom only in the five patients with an A8344G mitochondrial DNA point mutation with classic myoclonus epilepsy with ragged red fibers (MERRF) syndrome or “overlapping” characteristics. Photoparoxysmal EEG responses were observed not only in patients with typical MERRF, but also in adult patients with ME with lactic acidosis and strokelike episodes (MELAS), or overlapping phenotypes, and in one child with Leigh syndrome. Conclusions: Epilepsy is an important sign in the early presentation of ME and may be the most apparent neurologic sign of nontypical ME, often leading to the diagnostic workup. Except for those with an A8344G mitochondrial DNA point mutation, most of our patients had partial seizures or EEG signs indicating a focal origin.

Myasthenia Gravis (MG): Epidemiological Data and Prognostic Factors

Abstract: Data from 756 myasthenic patients were analyzed for diagnostic criteria, clinical aspects, and therapeutic approaches. The patients were followed up at our institution from 1981 to 2001. Clinical evaluation was performed according to the myasthenia gravis score adopted at our clinic. Clinical features of each patient (comprising demographic, clinical, neurophysiological, immunological, radiological, and surgical data, as well as serial myasthenia gravis scores) were filed in a relational database containing more than 7000 records. Clinical efficacy and variables influencing outcome were assessed by life‐table methods and Cox proportional hazards regression analysis. Complete stable remission, as defined by the Task Force of the Medical Scientific Advisory Board of the Myasthenia Gravis Foundation of America, was the end point for good prognosis. Four hundred and ninety‐nine patients (66%) were female and 257 (34%) were male. Mean follow‐up was 55.1 ± 48.1 months. Onset of symptoms peaked in the third decade in females, whereas the male distribution was bimodal with peaks in the third and sixth decades. Modality of myasthenia gravis presentation was as follows: ocular, 39.3%; generalized, 28.5%; bulbar, 31.3%; and respiratory, 0.8%. Thymectomy was carried out on 63.7% of our patients by different approaches: (1) transcervical; (2) transsternal; (3) video‐thoracoscopic mini‐invasive surgery. The last approach has been preferentially used in more recent years and accounted for 62.4% of the thymectomized myasthenia gravis population. Univariate analysis and Kaplan‐Meier analysis showed that variables such as sex (female), age at onset (below 40 years), thymectomy, and histological diagnosis of thymic hyperplasia were significantly associated with complete stable remission, whereas on multivariate analysis only age at onset below 40 years and thymectomy were confirmed.

Phenotypic manifestations associated with CAG-repeat expansion in the androgen receptor gene in male patients and heterozygous females: a clinical and molecular study of 30 families

Spinal and bulbar muscular atrophy (Kennedy disease) is an adult form of X-linked motor neuron disease caused by the expansion of a polymorphic CAG-repeat sequence in the first exon of the androgen receptor gene. We studied clinical and molecular features of 36 patients and 19 heterozygous females. Phenotypic manifestations and disease severity broadly varied among our spinal and bulbar muscular atrophy patients. The size of CAG expansion significantly influences the age of disease onset, but neither clinical features nor disease severity. The majority of carrier women presented signs of chronic denervation at neurophysiological examination and, in three cases, low-amplitude sensory action potentials were recorded. Notably, a few women developed mild signs of bulbar motor neuron impairment later in life. The identification of a large number of patients by the use of the molecular test further supports the hypothesis that Kennedy disease had been previously underdiagnosed, probably because of the great variability of clinical presentation. Although an early diagnosis may not be crucial for treatment, given the lack of effective therapy, the molecular testing can be of great relevance for disease prognosis and genetic counseling.

A comprehensive analysis of the epidemiology and clinical characteristics of anti-LRP4 in myasthenia gravis.

Double-seronegative myasthenia gravis (dSN-MG, without detectable AChR and MuSK antibodies) presents a serious gap in MG diagnosis and understanding. Recently, autoantibodies against the low-density lipoprotein receptor-related protein 4 (LRP4) have been identified in several dSN-MG sera, but with dramatic frequency variation (∼2-50%). We have developed a cell based assay (CBA) based on human LRP4 expressing HEK293 cells, for the reliable and efficient detection of LRP4 antibodies. We have screened about 800 MG patient sera from 10 countries for LRP4 antibodies. The overall frequency of LRP4-MG in the dSN-MG group (635 patients) was 18.7% but with variations among different populations (range 7-32.7%). Interestingly, we also identified double positive sera: 8/107 anti-AChR positive and 10/67 anti-MuSK positive sera also had detectable LRP4 antibodies, predominantly originating from only two of the participating groups. No LRP4 antibodies were identified in sera from 56 healthy controls tested, while 4/110 from patients with other neuroimmune diseases were positive. The clinical data, when available, for the LRP4-MG patients were then studied. At disease onset symptoms were mild (81% had MGFA grade I or II), with some identified thymic changes (32% hyperplasia, none with thymoma). On the other hand, double positive patients (AChR/LRP4-MG and MuSK/LRP4-MG) had more severe symptoms at onset compared with any single positive MG subgroup. Contrary to MuSK-MG, 27% of ocular dSN-MG patients were LRP4 antibody positive. Similarly, contrary to MuSK antibodies, which are predominantly of the IgG4 subtype, LRP4 antibodies were predominantly of the IgG1 and IgG2 subtypes. The prevalence was higher in women than in men (female/male ratio 2.5/1), with an average disease onset at ages 33.4 for females and 41.9 for males. Overall, the response of LRP4-MG patients to treatment was similar to published responses of AChR-MG rather than to MuSK-MG patients.

Video-assisted thoracoscopic extended thymectomy and extended transsternal thymectomy (T-3b) in non-thymomatous myasthenia gravis patients: remission after 6 years of follow-up

The aims of this study were to assess the efficacy of video-assisted thoracoscopic extended thymectomy (VATET) as a treatment for myasthenia gravis (MG) and to identify prognostic factors for thymectomy success. Clinical efficacy and variables influencing outcome were assessed by life-table and Cox proportional hazards regression analysis. Complete stable remission (CSR), as defined by the MGFA Medical Task Force, was the end point for efficacy. VATET was performed in 159 MG patients and T-3b in 47 MG patients. At 6 years of follow-up, CSR, assessed by life-table analysis, was 50.6% in non-thymomatous VATET patients and 48.7% in non-thymomatous T-3b surgery. By univariate analysis, the presence of thymic hyperplasia (P=0.0002) and treatment only with anticholinesterases (P<0.0001) were positively associated with the probability of CSR. By multivariate analysis, the chance of complete remission was significantly increased by the use of anticholinesterases (odds ratio [OR] 2.45; 95% confidence interval [CI] 1.44-4.17; P=0.001) and the presence of thymic hyperplasia (OR 1.96; 95% CI 1.05-3.68; P=0.036). VATET seems to be effective in inducing CSR in MG with an efficiency similar to that of the T-3b transsternal (TS) approach; it is easy to perform in experienced hands and is associated with low morbidity and negligible esthetic sequelae.

Azathioprine as a single drug or in combination with steroids in the treatment of myasthenia gravis

SummaryAzathioprine (Aza) has been used alone or in combination with steroids for two groups of myasthenic patients. Positive responses were noted in 75% of patients on Aza alone and in 70% receiving the combined regimen. The clinical course of the two groups differed in terms of respiratory crisis and need for plasma exchange. With an appropriate Aza administration schedule side-effects were not a limiting factor to its use. Aza treatment induced a reduction in anti-AchR-antibody level that was correlated with clinical improvement and greatly decreased the need for steroids.

Genotype to phenotype correlations in mitochondrial encephalomyopathies associated with the A3243G mutation of mitochondrial DNA

We studied 22 subjects carrying the A3243G point mutation of human mitochondrial DNA (mtDNA). In 14 cases the clinical phenotype was characterized by mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes (MELAS), while 8 patients had chronic progressive external ophthalmoplegia (CPEO). The proportion of A3243G heteroplasmy in muscle was determined by two methods: densitometry on a diagnostic restriction-fragment length polymorphism and solid-phase mini-sequencing. We found a highly significant inverse correlation between the percentage of A3243G mutation and the specific activity of complex 1, the respiratory complex with the highest number of mtDNA-encoded subunits, suggesting a direct effect of the mutation on mtDNA translation. No correlation was observed between the percentage of mutated mtDNA and the presence or absence of specific clinical features, such as stroke, ophthalmoplegia and diabetes mellitus. However, in the MELAS group the percentage of mutated mtDNA molecules was strongly correlated with the age of onset, while no such correlation was found in the CPEO group, suggesting a different time-dependent evolution of the mutation in the two groups. Finally, in contrast with other mtDNA mutations associated with ragged-red fibres (RRF), in both MELAS3243 and CPE03243 we observed a high proportion of RRF that were positive to the histochemical reaction to cytochromec oxidase, a morphological feature that seems to be specific for the neuromuscular phenotypes associated with mutations affecting the tRNALeu(UUR) gene.

Prognosis of myasthenia gravis: A multicenter follow-up study of 844 patients

The prognosis of myasthenia gravis (MG) was assessed retrospectively using life-table analysis in 844 patients followed up for a mean period of 5 years in 3 major Italian centers. The chance of achieving at least a 1-year remission after treatment withdrawal (complete remission) was assessed as a specific end-point in the whole population and in selected subgroups with reference to the principal prognostic variables. The cumulative probability of complete remission was 1% by 1 year, 8% by 3 years, 13% by 5 years, and 21% by 10 years. The only variables correlated to the chance of complete remission were younger age at onset of MG, lower severity of symptoms at onset and nadir, and shorter disease duration at diagnosis. In addition, thymectomy and early surgery seemed to influence the chance of remission. Other factors (including the presence of thymoma) did not significantly influence the outcome of the disease.