Exome sequencing detection of two untranslated GFPT1 mutations in a family with limb-girdle myasthenia.

The term 'limb-girdle myasthenia' (LGM) was first used to describe three siblings with proximal limb weakness without oculobulbar involvement, but with EMG decrement and responsiveness to anticholinesterase medication. We report here that exome sequencing in the proband of this family revealed several sequence variations in genes linked to proximal limb weakness. However, the only mutations that cosegregated with disease were an intronic IVS7-8A>G mutation and the previously reported 3'-UTR c.*22C>A mutation in GFPT1, a gene linked to LGM. A minigene assay showed that IVS7-8A>G activates an alternative splice acceptor that results in retention of the last seven nucleotides of intron 7 and a frameshift leading to a termination codon 13 nucleotides downstream from the new splice site. An anconeus muscle biopsy revealed mild reduction of the axon terminal size and postsynaptic fold simplification. The amplitudes of miniature endplate potentials and quantal release were also diminished. The DNA of the mildly affected father of the proband showed only the intronic mutation along with sequence variations in other genes potentially relevant to LGM. Thus, this study performed in the family originally described with LGM showed two GFPT1 untranslated mutations, which may cause disease by reducing GFPT1 expression and ultimately impairing protein glycosylation.

Congenital myasthenic syndrome associated with epidermolysis bullosa caused by homozygous mutations in PLEC1 and CHRNE.

Mutations in the plectin gene (PLEC1) cause epidermolysis bullosa simplex (EBS), which may associate with muscular dystrophy (EBS-MD) or pyloric atresia (EBS-PA). The association of EBS with congenital myasthenic syndrome (CMS) is also suspected to result from PLEC1 mutations. We report here a consanguineous patient with EBS and CMS for whom mutational analysis of PLEC1 revealed a homozygous 36 nucleotide insertion (1506_1507ins36) that results in a reduced expression of PLEC1 mRNA and plectin in the patient muscle. In addition, mutational analysis of CHRNE revealed a homozygous 1293insG, which is a well-known low-expressor receptor mutation. A skin biopsy revealed signs of EBS, and an anconeus muscle biopsy showed signs of a mild myopathy. Endplate studies showed fragmentation of endplates, postsynaptic simplification, and large collections of thread-like mitochondria. Amplitudes of miniature endplate potentials were diminished, but the endplate quantal content was actually increased. The complex phenotype presented here results from mutations in two separate genes. While the skin manifestations are because of the PLEC1 mutation, footprints of mutations in PLEC1 and CHRNE are present at the neuromuscular junction of the patient indicating that abnormalities in both genes contribute to the CMS phenotype.

Mutations in LAMB2 causing a severe form of synaptic congenital myasthenic syndrome.

BACKGROUND: We describe a severe form of congenital myasthenic syndrome (CMS) associated with congenital nephrosis and ocular malformations caused by two truncating mutations in the gene encoding the laminin beta2 subunit (LAMB2). METHODS AND RESULTS: Mutational analysis in the affected patient, who has a history of a serious untoward reaction to treatment with acetylcholinesterase inhibition, revealed two frame-shifting heteroallelic mutations, a maternally inherited 1478delG and a paternally inherited 4804delC. An anconeus muscle biopsy demonstrated a profound distortion of the architecture and function of the neuromuscular junction, which was strikingly similar to that seen in mice lacking laminin beta2 subunit. The findings included: pronounced reduction of the axon terminal size with encasement of the nerve endings by Schwann cells, severe widening of the primary synaptic cleft and invasion of the synaptic space by the processes of Schwann cells, and moderate simplification of postsynaptic folds and intact expression of the endplate acetylcholinesterase. The endplate potential quantal content was notably reduced, while the frequencies and amplitudes of miniature endplate potentials were only moderately diminished and the decay phases of miniature endplate potentials were normal. Western blot analysis of muscle and kidney tissue and immunohistochemistry of kidney tissue showed no laminin beta2 expression. CONCLUSION: This case, which represents a new type of synaptic CMS, exemplifies the wide variability of phenotypes associated with LAMB2 mutations and underscores the fundamental role that laminin beta2 plays in the development of the human neuromuscular junction.

Gamma-sarcoglycan deficiency leads to muscle membrane defects and apoptosis independent of dystrophin.

gamma-Sarcoglycan is a transmembrane, dystrophin-associated protein expressed in skeletal and cardiac muscle. The murine gamma-sarcoglycan gene was disrupted using homologous recombination. Mice lacking gamma-sarcoglycan showed pronounced dystrophic muscle changes in early life. By 20 wk of age, these mice developed cardiomyopathy and died prematurely. The loss of gamma-sarcoglycan produced secondary reduction of beta- and delta-sarcoglycan with partial retention of alpha- and epsilon-sarcoglycan, suggesting that beta-, gamma-, and delta-sarcoglycan function as a unit. Importantly, mice lacking gamma-sarco- glycan showed normal dystrophin content and local- ization, demonstrating that myofiber degeneration occurred independently of dystrophin alteration. Furthermore, beta-dystroglycan and laminin were left intact, implying that the dystrophin-dystroglycan-laminin mechanical link was unaffected by sarcoglycan deficiency. Apoptotic myonuclei were abundant in skeletal muscle lacking gamma-sarcoglycan, suggesting that programmed cell death contributes to myofiber degeneration. Vital staining with Evans blue dye revealed that muscle lacking gamma-sarcoglycan developed membrane disruptions like those seen in dystrophin-deficient muscle. Our data demonstrate that sarcoglycan loss was sufficient, and that dystrophin loss was not necessary to cause membrane defects and apoptosis. As a common molecular feature in a variety of muscular dystrophies, sarcoglycan loss is a likely mediator of pathology.

The clinical significance of extracellular matrix in gangliogliomas.

Based on in vitro studies which demonstrate that collagen IV and laminin inhibit the proliferation and invasiveness of glioma cells, we investigated the clinical significance of these extracellular matrix proteins (ECM) in patients with gangliogliomas, tumors in which ECM is often a prominent feature. Our study compared the relative presence and deposition pattern of collagen IV and laminin in 19 gangliogliomas and in 18 gliomas without ganglion cell differentiation (8 low-grade astrocytomas, 7 anaplastic astrocytomas, and 3 anaplastic mixed gliomas). We also examined whether the presence of collagen IV and laminin correlated with other features often observed in gangliogliomas, including perivascular lymphocytic inflammation, granular bodies, microcalcification, and subarachnoid extension, and whether any of these features were associated with the patient's clinical course. Significant deposition of collagen IV and laminin was found in 9 gangliogliomas (47%), but in none of the other gliomas. The presence of these extracellular proteins in gangliogliomas correlated with both perivascular inflammation (P = 0.003), and involvement of the leptomeninges by tumor (P = 0.008). The duration of symptoms prior to surgical resection was significantly longer for patients whose tumors showed extracellular deposition of collagen IV and laminin than for patients whose tumors lacked deposition of these proteins (mean 13.7 vs 5.1 years; P = 0.02). In addition, the duration of symptoms was significantly longer for patients whose tumors exhibited perivascular inflammation than for patients whose tumors displayed little or no perivascular inflammation (mean 14.8 vs 4.8 years; P = 0.01). These findings suggests that collagen IV and laminin and perivascular inflammation are related to the indolent behavior of gangliogliomas.

Inflammation at the neuromuscular junction in myasthenia gravis.

To better define the pathogenic mechanisms in the antibody-mediated autoimmune disease myasthenia gravis (MG), we analyzed the morphology and electrophysiology of the neuromuscular junction in anconeus muscle biopsy specimens from eight patients with MG and seven control subjects. There were inflammatory cells at the neuromuscular junction in seven of the eight biopsies from MG patients. The endplate index (length of the postsynaptic membrane divided by the length of the apposed presynaptic membrane) was abnormally reduced in all the MG patients, and fiber type grouping, suggestive of reinnervation, was present in six of the eight MG patients. Intracellular recording revealed diminished amplitude of miniature endplate potentials and miniature endplate currents in the MG patients compared with the controls. The time constant of decay of miniature endplate currents did not differ from that of controls, suggesting no change in mean channel open time of the acetylcholine receptor. The endplate receptor sensitivity to iontophoretically applied acetylcholine was also decreased in MG patients compared with controls. The quantal content of neurally evoked endplate potentials was reduced in six of the eight MG patients, demonstrating abnormal presynaptic function as well. The presence of inflammatory cells at the neuromuscular junctions of limb muscles in MG reconciles an apparent disparity between the animal model of MG, experimental autoimmune myasthenia gravis, and the human disease. This study also demonstrates a frequent presynaptic component to the abnormal neuromuscular transmission in MG.

Muscle acid protease activity in amyotrophic lateral sclerosis: correlation with clinical and pathologic features.

Acid protease activity was increased in skeletal muscle of patients with ALS. The highest levels of activity were found in individuals with the clinically and histologically most affected muscle. High levels of proteolytic activity correlated with the extent of muscle atrophy, the presence of target fibers and the overall severity of disease.

Immunologic and virologic studies of measles inclusion body encephalitis in an immunosuppressed host: the relationship to subacute sclerosing panencephalitis.

An immunosuppressed child with acute lymphoblastic leukemia in clinical remission developed measles inclusion body encephalitis (MIBE). Although measles antigen and nonbudding measles virus nucleocapsids were detected in brain tissue, no virus was isolated. Immune precipitation of measles virus proteins with the patient's serum showed no detectable antibody to virus M protein, a finding that has been reported in subacute sclerosing panencephalitis (SSPE). The virologic and immune precipitation studies suggest a similar virus mutation in MIBE and SSPE. The pathogenesis of the two diseases may also be similar.

Clinical and genetic studies of fatal familial insomnia.

We report a 42-year-old man who, for 8 months, had intermittent motor abnormalities and mild difficulty falling asleep. A diagnosis of fatal familial insomnia (FFI) became evident over the next 6 months when he developed progressive insomnia, myoclonus, sympathetic hyperactivity, and dementia. The amyloid or prion protein (PrP) genotype showed features typically seen in FFI, with a 178Asn mutation and a 129Met polymorphism. There was also a deletion of one octapeptide repeat, suggesting that the association of 178Asn mutation with the 129Met polymorphism is not due to "founder effect." Western immunoblot showed a trace of protease-resistant PrP in the thalamus--which had the most significant neuronal loss and gliosis--a moderate amount of PrP in the fronto-temporal area, and no detectable protein elsewhere in the brain. Endocrine studies showed that a circadian modulation of hormonal levels could be maintained despite a near-total absence of sleep. Administration of gamma-hydroxybutyrate induced a remarkable increase in slow-wave sleep.

Presynaptic congenital myasthenic syndrome due to quantal release deficiency.

OBJECTIVE: To provide clinical, electrophysiologic, and ultrastructural findings in three patients with a presynaptic congenital myasthenic syndrome (CMS). BACKGROUND: Familial infantile myasthenia and paucity of synaptic vesicles are the only two fully characterized CMS. We are describing here three patients with another form of presynaptic CMS characterized by deficiency of the action potential-dependent release without reduction of the spontaneous release of neurotransmitter from the nerve terminal. METHODS: The authors performed electromyography and anconeus muscle biopsies that included intracellular recordings and electron microscopy of the neuromuscular junction in three patients with presynaptic CMS. They also sequenced part of the P/Q-calcium alpha(1)-subunit gene (CACNA1A) and the acetylcholine receptor subunit (AChR) genes in these patients. RESULTS: In these patients there were additional neurologic findings including nystagmus and ataxia. In all three patients the end-plate potential quantal content (m) was markedly reduced but neither the amplitudes nor the frequencies of miniature end-plate potentials were diminished. Ultrastructurally, postsynaptic end-plate folds, nerve terminal size, and synaptic vesicle number were normal but double-membrane-bound sacs containing synaptic vesicles were present in the nerve terminal of all three patients. The screening of reported pathogenic mutations in the CACNA1A and a mutational analysis of AChR subunit genes were negative. CONCLUSION: This form of CMS appears to result only from a deficiency of the quantal release of neurotransmitter that may be due to an abnormal calcium mechanism or impaired endocytosis and recycling of synaptic vesicles.

Sympathectomy augments adoptively transferred experimental allergic encephalomyelitis.

Adoptively transferred experimental allergic encephalomyelitis (EAE) was significantly augmented in Lewis rats with ablated sympathetic nervous system. Sympathectomy was obtained by treatment of newborn rats with 6-hydroxydopamine. Sham-injected rats were used as a control. EAE was elicited in 7-8-week-old donor Lewis rats by immunization with a suspension of guinea pig (GP) brain and spinal cord in complete Freund's adjuvant. Successful transfer of EAE was accomplished with 50 x 10(6) lymph node cells (LNC)/rat, incubated for 72 h with GP myelin basic protein. LNC were obtained from draining lymph nodes, 9 days after immunization for EAE. The severity of passively transferred EAE was significantly augmented when donor LNC obtained from normal Lewis rats immunized for EAE were injected into sympathectomized rats as compared to sham-injected rats. When LNC were obtained from sympathectomized or sham-injected donors, the disease was significantly more severe in recipients of cells from sympathectomized animals. The severity of histological lesions in the brain and spinal cord was greater in rats with passively transferred EAE which received LNC from sympathectomized donors.

Cellular neuropathology of tuberous sclerosis.

The study of cerebral lesions of TSC by special histologic methods suggests that two populations of neurons and glia occur in TSC brains. One is a population of normally differentiated cells that form a normally constituted cortical plate. The other is a group of cells that are poorly differentiated, fail to organize into a normal cortical architecture, and form a variety of abnormal cellular aggregates in cortex and in subcortical locations. The proportion of these abnormal cells varies greatly from patient to patient. In some the central nervous system appears to be entirely spared. In others, only one or a few islands of dysplastic cells occur, whereas in still others a large number, perhaps even a majority, of neuroectodermal cells in the forebrain may be affected. The proportion of total cells that undergo abnormal differentiation apparently is an important factor relative to cortical function in TSC. At present we have no explanation for this marked heterogeneity in expression of the TSC gene or genes, and it remains one of the many unsolved mysteries of this illness.

Distribution of S-100 protein outside the central nervous system.

The distribution of S-100 outside the central nervous system in humans and rats was explored using antiserum to S-100 and the peroxidase anti-peroxidase method of Sternberger. In peripheral nerves the Schwann cells and the outermost part of the myelin sheaths were stained; axons were not. In dorsal root ganglia and ganglia of the autonomic nervous system only satellite cells were stained. In the adrenal medulla a considerable number of cells were stained. In all other organs studied Schwann cells and satellite cells of ganglia were the only elements that were stained. We conclude that S-100 could serve as a marker for Schwann cells in situ.

Maintenance of isolated oligodendrocytes in long-term culture.

A new procedure for isolating oligodendrocytes from ovine white matter is described. The method separates oligodendrocytes into two bands on a linear sucrose gradient. Five criteria have been employed to classify the separated cells. It is shown by indirect immunofluorescence with specific antisera that 97% of the cells from both bands carry galactocerebroside, a specific surface marker for oligodendrocytes, on their plasma membranes and 95% of the cells retain myelin basic protein as distinct patches on their surfaces. Isolated cells conform ultrastructurally to current concepts of oligodendrocytes. The cells incorporate [3H]galactose into galactocerebroside and carrier free H2(35)SO4 into sulfatide, specific markers for oligodendrocytes. The specific activity of 2',3'-cyclic nucleotide-3'-phosphodiesterase in the two cell fractions is comparable to that reported for isolated oligodendrocytes by others. It is concluded that conservatively, 95% of the cells in both fractions are oligodendrocytes. Cells from both bands survive in culture for months. In vitro the cells extend two or more processes, contain 'gliosomes', and surround themselves with extensive sheet-like membranes; i.e. they exhibit the morphological characteristics ascribed to oligodendrocytes in explant cultures. Conservatively 90% of cultured cells stain with an antimyelin basic protein serum. The staining is localized in the cytoplasm and processes. The cells also stain with antigalactocerebroside and antioligodendrocyte sera. Cells remain differentiated for up to 70 days in vitro as evidenced by their incorporation of [3H]galactose and H2(35)SO4 into galactosyl and sulfogalactosylceramide, respectively.

Myopathy induced by epsilon-aminocaproic acid. Case report.

The authors present a case of proximal myopathy secondary to epsilon-aminocaproic acid (EACA) administration. This well recognized entity does not occur immediately after institution of therapy, but follows a delay of several days and a cumulative dose. Its consequences include a spectrum of symptoms from myalgias to severe myopathy with rhabdomyolysis, myoglobinuria, and acute tubular necrosis. A presenting symptom of calf pain in a patient receiving EACA should not automatically imply deep vein thrombosis. Serial creatine phosphokinase measurements are essential in monitoring a patient undergoing EACA therapy, especially after 2 weeks of treatment and a total dose of greater than 500 gm.

The effect of fetal hypothalamus grafts on weight gain resulting from lesions of the ventromedial hypothalamus.

Bilateral ventromedial hypothalamic lesions in female adult rats which resulted in hyperphagia and rapid weight gain were followed by placement of fetal brain tissue in the anterior third ventricle. The treatment group received fetal hypothalamus grafts, and fetal cortical tissue of identical age was grafted into the control group. A significant reduction in average daily weight gain was noted from 4 to 12 weeks following transplantation in the treatment group. At 12 weeks posttransplantation, the animals were sacrificed for histological analysis. Examination of the hypothalamus grafts revealed neurons, ependymal clusters, and axonal processes which appeared to infiltrate the surrounding hypothalamic parenchyma.

Disseminated histoplasmosis in an infant with acquired immunodeficiency syndrome.

Disseminated histoplasmosis has been recognized as a serious opportunistic infection in patients with acquired immunodeficiency syndrome (AIDS). However, cases reported in the literature have been predominantly in adult patients. Here we report an infant with AIDS who presented with fever, cough, rhinorrhea, hepatosplenomegaly, pancytopenia and coagulopathy, and died of respiratory failure. Autopsy revealed disseminated histoplasmosis involving multiple organs including lungs, intestines, liver, spleen, bone marrow, lymph nodes, kidneys, and meninges. The diagnosis was established based on histomorphology and confirmed by blood culture.

Venous angiomas of the posterior fossa should be considered as anomalous venous drainage.

Venous angioma of the posterior fossa has been described, and the existing literature has been reviewed. The patient presented had a venous angioma located in the pons, and both cerebellar hemispheres and was drained by an enlarged and anatomically anomalous vein within the fourth ventricle. The patient had a "cough headache" and later had signs of cerebellar involvement. A surgical attempt at collapsing the anomalous vein resulted in death in the immediate postoperative period due to venous infarction of the brain stem and cerebellum. Emphasis has been given to the following: 1. "Cough Headache" can be a presenting feature for venous angiomas of the posterior fossa. 2. Venous angiomas of the posterior fossa are developmental anatomic anomalies with enlargement of certain venous structures as a result of inadequate alternative venous drainage. 3. The enlarged vein, which is the pathognomonic feature of venous angiomas, serves a vital function in drainage of blood from structures in the posterior fossa as the usual drainage pathways are inadequate or absent. 4. Operative intervention aimed at resection or collapse of such large veins, which has been successful in treatment of venous angiomas of the frontal lobe, can be disastrous in the treatment of those lesions occurring in the posterior fossa.

Calcified basal ganglionic mass 12 years after radiation therapy for medulloblastoma.

A patient treated 12 years previously with an operation and radiation therapy for a medulloblastoma developed weakness of the left hand and perivascular calcification involving the right internal capsule and caudate nucleus. These findings are considered possible long-term complications of the radiation therapy.

Superior sagittal sinus thrombosis diagnosed by computed tomography.

Superior sagittal sinus thrombosis is an often unrecognized clinical condition. This is due to its variable clinical presentation and its association with other serious disease states. The following cases demonstrate that, in the infant, thrombosis of the superior sagittal sinus can be diagnosed quickly and noninvasively by computed tomography (CT). In those clinical situations in which thrombosis of the superior sagittal sinus may occur and neurological changes exist, axial and coronal CT scans may be quite specific in detecting its occurrence.