Helga C. A. Silva

A Mutation in the Vesicle-Trafficking Protein VAPB Causes Late-Onset Spinal Muscular Atrophy and Amyotrophic Lateral Sclerosis

Motor neuron diseases (MNDs) are a group of neurodegenerative disorders with involvement of upper and/or lower motor neurons, such as amyotrophic lateral sclerosis (ALS), spinal muscular atrophy (SMA), progressive bulbar palsy, and primary lateral sclerosis. Recently, we have mapped a new locus for an atypical form of ALS/MND (atypical amyotrophic lateral sclerosis [ALS8]) at 20q13.3 in a large white Brazilian family. Here, we report the finding of a novel missense mutation in the vesicle-associated membrane protein/synaptobrevin-associated membrane protein B (VAPB) gene in patients from this family. Subsequently, the same mutation was identified in patients from six additional kindreds but with different clinical courses, such as ALS8, late-onset SMA, and typical severe ALS with rapid progression. Although it was not possible to link all these families, haplotype analysis suggests a founder effect. Members of the vesicle-associated proteins are intracellular membrane proteins that can associate with microtubules and that have been shown to have a function in membrane transport. These data suggest that clinically variable MNDs may be caused by a dysfunction in intracellular membrane trafficking.

Telethonin protein expression in neuromuscular disorders.

Telethonin is a 19-kDa sarcomeric protein, localized to the Z-disc of skeletal and cardiac muscles. Mutations in the telethonin gene cause limb-girdle muscular dystrophy type 2G (LGMD2G). We investigated the sarcomeric integrity of muscle fibers in LGMD2G patients, through double immunofluorescence analysis for telethonin with three sarcomeric proteins: titin, alpha-actinin-2, and myotilin and observed the typical cross striation pattern, suggesting that the Z-line of the sarcomere is apparently preserved, despite the absence of telethonin. Ultrastructural analysis confirmed the integrity of the sarcomeric architecture. The possible interaction of telethonin with other proteins responsible for several forms of neuromuscular disorders was also analyzed. Telethonin was clearly present in the rods in nemaline myopathy (NM) muscle fibers, confirming its localization to the Z-line of the sarcomere. Muscle from patients with absent telethonin showed normal expression for the proteins dystrophin, sarcoglycans, dysferlin, and calpain-3. Additionally, telethonin showed normal localization in muscle biopsies from patients with LGMD2A, LGMD2B, sarcoglycanopathies, and Duchenne muscular dystrophy (DMD). Therefore, the primary deficiency of calpain-3, dysferlin, sarcoglycans, and dystrophin do not seem to alter telethonin expression.

Fatigue in amyotrophic lateral sclerosis: Frequency and associated factors

We aimed to quantify fatigue frequency and evolution in amyotrophic lateral sclerosis (ALS), and to correlate fatigue with factors such as age, sex, educational level, disease duration, functionality, quality of life, dyspnoea, depression and sleepiness. Sixty ALS patients (test group: TG) selected by El Escorial criteria and 60 normal individuals (control group: CG) matched according to sex and age, were followed every three months, during 9 months, by means of self‐report scales: Fatigue Assessment Instrument (Fatigue Severity Scale plus three qualitative subscales); ALS Functional Rating Scale; McGill Quality of Life Questionnaire; dyspnoea analogical scale; Beck Depression Inventory and Epworth Sleepiness Scale. Fatigue was reported by 83% of TG (median: 3.6, interquartile range 1.5−5.4), compared with 20% of CG (median: 1, 1−1), and was significantly greater in the TG (p<0.001, Mann‐Whitney test). Fatigue severity increased by the ninth month of the study (p = 0.0008, Friedman, Müller‐Dunn post test). There was no correlation between fatigue and other parameters, except for an inverse correlation with age at disease onset (p = 0.0395, Spearman rank correlation). In conclusion, fatigue was frequent in ALS, greater in the youngest patients and worsened during follow‐up. Possibly, ALS related fatigue is an independent factor, which deserves individualized approach and treatment.

Transcriptional regulation differs in affected facioscapulohumeral muscular dystrophy patients compared to asymptomatic related carriers.

Facioscapulohumeral muscular dystrophy (FSHD) is a progressive muscle disorder that has been associated with a contraction of 3.3-kb repeats on chromosome 4q35. FSHD is characterized by a wide clinical inter- and intrafamilial variability, ranging from wheelchair-bound patients to asymptomatic carriers. Our study is unique in comparing the gene expression profiles from related affected, asymptomatic carrier, and control individuals. Our results suggest that the expression of genes on chromosome 4q is altered in affected and asymptomatic individuals. Remarkably, the changes seen in asymptomatic samples are largely in products of genes encoding several chemokines, whereas the changes seen in affected samples are largely in genes governing the synthesis of GPI-linked proteins and histone acetylation. Besides this, the affected patient and related asymptomatic carrier share the 4qA161 haplotype. Thus, these polymorphisms by themselves do not explain the pathogenicity of the contracted allele. Interestingly, our results also suggest that the miRNAs might mediate the regulatory network in FSHD. Together, our results support the previous evidence that FSHD may be caused by transcriptional dysregulation of multiple genes, in cis and in trans, and suggest some factors potentially important for FSHD pathogenesis. The study of the gene expression profiles from asymptomatic carriers and related affected patients is a unique approach to try to enhance our understanding of the missing link between the contraction in D4Z4 repeats and muscle disease, while minimizing the effects of differences resulting from genetic background.

Amyotrophic lateral sclerosis in Brazil: 1998 national survey

OBJECTIVES To assess the epidemiologic characteristics of amyotrophic lateral sclerosis (ALS) in Brazil in 1998. METHOD Structured Clinical Report Forms (CRFs) sent to 2,505 Brazilian neurologists from January to September 1998 to be filled with demographic and clinical data regarding any ALS patient seen at any time during that year. RESULTS Five hundred and forty CRFs were returned by 168 neurologists. Data on 443 patients meeting the criteria of probable or definite ALS according to El Escorial definition were analysed: 63 probable (14.2%) and 380 definite (85. 8%). Two hundred and fifty-nine (58.5%) of the patients were male, mean age of onset was 52. Spinal onset occurred in 306 patients (69%); bulbar onset in 82 (18.5%), and both in 52 (11.7%). Twenty-six (5.9%) had a family history of ALS. Two hundred and fifty-nine (58.6%) were seen by private practitioners, and 178 (40. 2%) at a hospital clinic. Age-ajusted incidence shows a peak incidence at the 65-74 years old range. CONCLUSIONS The diseases characteristics are similar to those described in international studies, except for age of onset (Brazilian patients are younger). This difference is not confirmed when figures are age-adjusted.

Magnetic resonance imaging in five patients with a tumefactive demyelinating lesion in the central nervous system

Five patients with a tumefactive lesion were clinically followed from 1992 to 1993. Four patients were female; age ranged from 32 to 57 years, the duration of symptoms varied from 3 days to 3 years. Neurological examination disclosed dementia in two patients, aphasia in three, hemiparesis in four, hemihypoaesthesia in three, optical neuritis in two, tetraparesis with sensitive level and neurogenic bladder in one. MRI disclosed lesions with a hypersignal on images assessed at T2 and hyposignal at T1, and gadolinium heterogeneous enhancement; these lesions were located in the: a) temporooccipital region bilaterally and brain stem, b) frontoparietal white matter, c) basal ganglia, bilateral white matter and brain stem, d) left parietal region, e) cervical spinal cord, with enlargement of this region. Cerebral biopsy was performed in three patients; acute and subacute demyelinating disease was diagnosed by histological examination. Two patients had an evolutive diagnosis; exclusion of other pathologies and clinical and radiological improvement after corticotherapy, pointed to an inflammatory disease.

Intractable complex partial seizures associated with posterior cerebral artery giant aneurysm: a case report.

Summary: Giant aneurysms have rarely been reported in association with intractable complex partial seizures (CPS). We report a 30‐year‐old man with intractable CPS since age 18 years. Seizure onset was electrically localized to right temporal lobe. Preoperative neuroimaging studies showed a partially thrombosed giant aneurysm of the right posterior cerebral artery. Selective arnygdalo‐ hippocampectomy and occlusion of the posterior cerebral artery did not cause deficits. The patient has been seizure‐free for 15 months after operation. We review the relevant literature on aneurysms as a cause of epilepsy.

ALTERACOES SEXUAIS NA EPILEPSIA: RESULTADOS DE UMA AVALIACAO MULTIDISCIPLINAR

Eleven epileptic men who complained of epilepsy and sexual dysfunction were submitted to a multidisciplinary evaluation. Mean age was 27 years (20-34), mean epilepsy duration was 19 years (0,5-32) and the mean seizure frequency was two by week (0-7). Ten patients had partial seizures and one other had myoclonic epilepsy. Ten patients were treated with antiepileptic drugs (phenytoin - 1, carbamazepine - 8, clonazepam - 3, clobazam - 2, valproic acid - 3, vigabatrin - 1). As defined in the DSM III-R, the complaints were: erectile disorder (9), hypoactive sexual desire disorder (4), frotteurism (4), inhibited orgasm (3), premature ejaculation (3), fetishism (2), voyeurism (2), exhibitionism (2), pedophilia (1) and sexual aversion disorder (1). Two patients showed hypogonadotropic hypogonadism on endocrinologic screening. Urological evaluation disclosed organic erectile dysfunction in other two. One patient had a diagnosis of psychogenic sexual disorder. In six patients a conclusive etiologic diagnosis was not reached This report shows the multifactorial nature of sexual disorder in epilepsy and underlies the need of a multidisciplinar evaluation.

Screening for mutations in the RYR1 gene in families with malignant hyperthermia

Malignant hyperthermia (MH) is a potentially lethal pharmacogenetic predisposition associated with a susceptibility to volatile anesthetics and depolarizing muscle relaxants that lead to a fulminant anesthetic crisis with hyperthermia, skeletal muscle rigidity, respiratory and metabolic acidosis, and muscle rhabdomyolysis. Malignant hyperthermia crises are caused by an abnormal regulation of the calcium release mechanism, which reflects the consequences of disturbed skeletal muscle calcium homeostasis. We screened 64 individuals of 27 unrelated families for the most frequently described mutations associated with MH in the genes RYR1 and CACNL1A3. We identified only one family with the Arg614Cys mutation but with a discordant segregating pattern to the in vitro contracture test (IVCT). To elucidate which other mechanism could lead to susceptibility in the members of this family, we tested it for further MH susceptibility loci. The same haplotype was shown to segregate with the individuals carrying the Arg614Cys mutation in chromosome 19; however, the other susceptible and equivocal individuals do not share this haplotype. Markers for the susceptible locus in chromosome regions 17q, 7q, 3q, and 5p did not segregate with the IVCT phenotype in the susceptible individuals, suggesting that the positivity of the IVCT could be attributable to other ambient factors.

Does the A3333G Mutation in the CACNL1A3 Gene, Detected in Malignant Hyperthermia, Also Occur in Central Core Disease?

Malignant hyperthermia (MH) and central core disease (CCD) are two conditions associated with susceptibility to volatile anesthetics and depolarizing muscle relaxants. The gene RYR1, encoding the Ca2+ release channel of skeletal muscle sarcoplasmic reticulum, is responsible for about 50% of the cases of MH and some cases of CCD. However, genetic heterogeneity occurs in MH and a mutation in a second gene (CACLN1A3), encoding the alpha1-subunit of the dihydropyridine (DHP) channel, has recently been found in a large MH French family. The presence of this mutation in patients with CCD has not yet been reported. In this study, we analyzed the A3333G mutation in 5 unrelated patients affected by CCD and 31 MH-susceptible relatives (from 19 MH families) and did not find this mutation in any of them. Nevertheless, the report of data on newly described mutations in different populations is important to estimate the contributions of each gene mutation to the phenotype of MH and CCD.