Myasthenic syndrome caused by plectinopathy.

BACKGROUND: Plectin crosslinks intermediate filaments to their targets in different tissues. Defects in plectin cause epidermolysis bullosa simplex (EBS), muscular dystrophy (MD), and sometimes pyloric atresia. Association of EBS with a myasthenic syndrome (MyS) was documented in a single patient in 1999. OBJECTIVES: To analyze the clinical, structural, and genetic aspects of a second and fatal case of EBS associated with a MyS and search for the genetic basis of the disease in a previously reported patient with EBS-MD-MyS. METHODS: Clinical observations; histochemical, immunocytochemical, and electron microscopy studies of skeletal muscle and neuromuscular junction; and mutation analysis. RESULTS: An African American man had EBS since early infancy, and progressive muscle weakness, hyperCKemia, and myasthenic symptoms refractory to therapy since age 3 years. Eventually he became motionless and died at age 42 years. At age 15 years, he had a marked EMG decrement, and a reduced miniature endplate potential amplitude. The myopathy was associated with dislocated muscle fiber organelles, structurally abnormal nuclei, focal plasmalemmal defects, and focal calcium ingress into muscle fibers. The neuromuscular junctions showed destruction of the junctional folds, and remodeling. Mutation analysis demonstrated a known p.Arg2319X and a novel c.12043dupG mutation in PLEC1. The EBS-MD-MyS patient reported in 1999 also carried c.12043dupG and a novel p.Gln2057X mutation. The novel mutations were absent in 200 Caucasian and 100 African American subjects. CONCLUSIONS: The MyS in plectinopathy is attributed to destruction of the junctional folds and the myopathy to defective anchoring of muscle fiber organelles and defects in sarcolemmal integrity.

Myasthenic syndrome due to defects in rapsyn: Clinical and molecular findings in 39 patients.

BACKGROUND: Pathogenic mutations in rapsyn result in endplate acetylcholine receptor (AChR) deficiency and are a common cause of postsynaptic congenital myasthenic syndromes. METHODS: Clinical, electrophysiologic, pathologic, and molecular studies were done in 39 patients. RESULTS: In all but one patient, the disease presented in the first 2 years of life. In 9 patients, the myasthenic symptoms included constant or episodic ophthalmoparesis, and 1 patient had a pure limb-girdle phenotype. More than one-half of the patients experienced intermittent exacerbations. Long-term follow-up was available in 25 patients after start of cholinergic therapy: 21 became stable or were improved and 2 of these became asymptomatic; 3 had a progressive course; and 1 died in infancy. In 7 patients who had endplate studies, the average counts of AChR per endplate and the synaptic response to ACh were less reduced than in patients harboring low AChR expressor mutations. Eight patients were homozygous and 23 heterozygous for the common p.N88K mutation. Six mutations, comprising 3 missense mutations, an in-frame deletion, a splice-site mutation, and a nonsense mutation, are novel. Homozygosity for p.N88K was associated with varying grades of severity. No genotype-phenotype correlations were observed except in 8 Near-Eastern patients homozygous for the promoter mutation (c.-38A>G), who had a mild course. CONCLUSIONS: All but 1 patient presented early in life and most responded to cholinergic agonists. With early diagnosis and therapy, rapsyn deficiency has a benign course in most patients. There was no consistent phenotype-genotype correlation except for an E-box mutation associated with jaw deformities.

Zaspopathy in a large classic late-onset distal myopathy family.

Distal myopathies have been associated with mutations in titin, dysferlin, GNE, desmin and myosin. Of these, only titin mutations were previously known to cause dominant late-onset distal myopathy. Recent findings, however, have indicated that patients affected with myofibrillar myopathy have a more distal than proximal muscle phenotype and a proportion of these may have mutations in myotilin, ZASP or filamin C, besides previously known desmin and alphaB-crystallin. Here we report that the disorder in one of the well-characterized autosomal dominant distal myopathy families, the Markesbery et al. family, first reported in 1974, is caused by ZASP mutation A165V. Previous linkage to the titin locus 2q31 proved incorrect. ZASP expression by immunoblotting shows normal presence of the main 32 and 78 kDa bands and immunohistochemistry in patients reveals normal Z-disc localization except for moderate accumulations together with myotilin, desmin alphaB-crystallin and alpha-actinin. Muscle imaging reveals involvement in both the posterior and anterior compartments of the lower leg and considerable affection of proximal leg muscles at later stages. Haplotype studies in this family and in five other unrelated families with European ancestry carrying the identical A165V mutation share common markers at the locus suggesting the existence of a founder mutation.

The earliest pathologic alterations in dysferlinopathy.

BACKGROUND: Dysferlinopathies are associated with proximal or distal muscular dystrophy. Dysferlin immunolocalizes to the muscle fiber periphery but does not associate with the dystrophin--glycoprotein complex; its function in humans, and the mechanism by which it causes muscle fiber injury, are not known. The authors therefore searched for pathogenetic clues by examining early abnormalities in nonnecrotic muscle fibers in dysferlinopathy. Five dysferlin-deficient patients were investigated. Weakness was distal in two, proximal in one, and both proximal and distal in two. Patient 5 was only mildly affected. METHODS: Immunoblot analysis, membrane attack complex (MAC) immunolocalization, and quantitative electron microscopy. RESULTS: In Patients 1 through 4, but not in 5, part or the entire surface of isolated nonnecrotic muscle fibers immunostained for MAC. Quantitative electron microscopy of 175 nonnecrotic muscle fibers revealed one or more of the following: 1) small (0.11 to 1.8 microm) plasmalemmal defects in 64% of fibers; 2) thickened basal lamina over some defects; 3) replacement of the plasma membrane by one to multiple layers of small vesicles in 57% of fibers; 4) papillary projections, frequently disintegrating, in 24 to 36% of fibers in Patients 1 through 4 but absent in fibers of Patient 5; 5) small subsarcolemmal vacuoles, some undergoing exocytosis, in 57% of fibers; and 6) infrequent subsarcolemmal regions containing rough endoplasmic reticulum and abundant free ribosomes. CONCLUSIONS: Dysferlin is likely required for maintaining the structural integrity of the muscle fiber plasma membrane, and plasma membrane injury is an early event in the pathogenesis of dysferlinopathy. MAC activation can participate in but is not an initial or primary event causing muscle fiber injury.

Myopathy with muscle spindle excess: A new congenital neuromuscular syndrome?

An infant presented with congenital weakness, hypotonia, arthrogryposis, atrial tachycardia, and a left intra-abdominal neuroblastoma. Muscle biopsy revealed marked excess of muscle spindles with atrophy of extrafusal fibers. The patient expired at age 14 months from progressive cardiorespiratory failure. Postmortem examination demonstrated muscle-spindle excess in other muscles, along with hypertrophic obstructive cardiomyopathy and organomegaly. Muscle spindle excess has previously been reported in two patients with Noonan syndrome and progressive hypertrophic cardiomyopathy. Muscle spindle excess with hypertrophic cardiomyopathy, organomegaly, and, possibly, congenital neuroblastoma suggests a syndromic association and may represent an unusual form of congenital myopathy.

Otocerebral anomalies associated with topical tretinoin use.

Topical preparations of tretinoin are used for the treatment of various skin conditions and for rejuvenation of the skin. Published information on pregnancy outcome following maternal exposure to topical tretinoin is limited to three case reports. We report a case of a patient with anomalies involving the ear and central nervous system with exposure to topical tretinoin during the first trimester. Though the potential link between the use of topical tretinoin and the existence of fetal malformations remains to be further documented by animal as well as epidemiological studies, we strongly recommend that the use of topical tretinoin during pregnancy should be discouraged, and effective contraception should be used in patients of childbearing age.

High-dose intravenous immunoglobulin therapy in juvenile myasthenia gravis.

Autoimmune neurologic disease management has been significantly modified by the use of high-dose intravenous immunoglobulin (HDIVIG) during the past 15 years. Venous access, readily available IgG (until recently), and the relative lack of serious identifiable complications have prompted its use in myasthenia gravis. In adults, its effectiveness has been inconsistent, with variable acetylcholine receptor (AChR) antibody responses. Ten children were evaluated for clinical responses to, and complications of, HDIVIG. Weekly anti-AChR antibody titers in three patients were obtained. The HDIVIG dosage was 2 gm/kg body weight, infused at variable rates of 2 gm/kg for 1 day, 0.66 gm/kg daily for 3 days, and 0.5 g/kg daily for 4 days; in one patient the total dose was 0.8 gm/kg to correct to the ideal body weight. All children but one tolerated HDIVIG without complications. Eight patients exhibited definite improvement in functional strength after HDIVIG, but a decreasing response to HDIVIG was evident after multiple monthly treatments, warranting the additional use of corticosteroids in two patients. A decrease in anti-AChR antibody levels was observed in the three patients tested, but this decrease was constant in one patient. No correlation was observed between clinical response and antibody titers. HDIVIG is safe and effective in most patients for short-term management of juvenile myasthenia gravis, in myasthenic crises, and in preparing patients for surgery but appears to be of limited long-term benefit.

Multiple sclerosis in childhood: report of 16 cases.

Sixteen children with definite multiple sclerosis (MS; aged 6-17 years, mean 11.4 +/- 2.7; 8 boys, 8 girls) were reviewed. Cerebellar symptoms and signs were frequent at initial presentation. Among laboratory studies, the cerebrospinal fluid (CSF) IgG index or oligoclonal bands were informative in 75%, evoked potentials in 70%, electroencephalography (EEG) in 83%, magnetic resonance imaging in 80% and computed tomography in 45%. When compared with patients with other neurological disorders and similar presentation (non-MS group, n = 13), MS patients were more likely to recover from the first attack without significant sequelae. CSF protein was usually normal in MS and high in non-MS patients. The CSF IgG index and/or oligoclonal bands were also helpful in differentiating these two groups. The absence of female preponderance, the frequency of EEG abnormalities and the lower yield from CSF analysis are particularly interesting in this childhood series. Different pathogenetic mechanisms may be involved in MS from different ages, genetic backgrounds, or environments.

Mucormycosis in a diabetic child and its treatment with fluconazole: a case report.

We present here a case of a diabetic patient having complaints of painful swelling of the left eye, blurring of the vision and tonic-clonic convulsion. Surgical exploration of the sinuses was performed, and the histopathological examination revealed mucomycosis. Because of the side effects of Amphotericin B, we tried Fluconazole and the patient recovered completely.