|
Congenital Myopathy
Congenital myopathy is a very broad term for any muscle disorder present at birth. This defect primarily affects skeletal muscle fibres and causes muscular weakness and/or hypotonia. Congenital myopathies account for one of the top neuromuscular disorders in the world today, comprising approximately 6 in 100,000 live births every year. As a whole, congenital myopathies can be broadly classified as follows: * A distinctive abnormality in skeletal muscle fibres on the cellular level; observable via light microscope * Symptoms of muscle weakness and hypotonia * Is a congenital disorder, meaning it occurs during development and symptoms present themselves at birth or in early life. * Is a genetic disorder. Classification Myopathies with inclusion bodies and abnormal protein accumulation Congenital myopathies with inclusion bodies and protein accumulation is a broad category, and some congenital myopathies that fall within this group are well understood, such as nemaline myopathy (see b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hypotonia
Hypotonia is a state of low muscle tone (the amount of tension or resistance to stretch in a muscle), often involving reduced muscle strength. Hypotonia is not a specific medical disorder, but a potential manifestation of many different diseases and disorders that affect motor nerve control by the brain or muscle strength. Hypotonia is a lack of resistance to passive movement, whereas muscle weakness results in impaired active movement. Central hypotonia originates from the central nervous system, while peripheral hypotonia is related to problems within the spinal cord, peripheral nerves and/or skeletal muscles. Severe hypotonia in infancy is commonly known as floppy baby syndrome. Recognizing hypotonia, even in early infancy, is usually relatively straightforward, but diagnosing the underlying cause can be difficult and often unsuccessful. The long-term effects of hypotonia on a child's development and later life depend primarily on the severity of the muscle weakness and the na ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cell Nucleus
The cell nucleus (pl. nuclei; from Latin or , meaning ''kernel'' or ''seed'') is a membrane-bound organelle found in eukaryotic cells. Eukaryotic cells usually have a single nucleus, but a few cell types, such as mammalian red blood cells, have no nuclei, and a few others including osteoclasts have many. The main structures making up the nucleus are the nuclear envelope, a double membrane that encloses the entire organelle and isolates its contents from the cellular cytoplasm; and the nuclear matrix, a network within the nucleus that adds mechanical support. The cell nucleus contains nearly all of the cell's genome. Nuclear DNA is often organized into multiple chromosomes – long stands of DNA dotted with various proteins, such as histones, that protect and organize the DNA. The genes within these chromosomes are structured in such a way to promote cell function. The nucleus maintains the integrity of genes and controls the activities of the cell by regulating gene expres ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Succinate Dehydrogenase
Succinate dehydrogenase (SDH) or succinate-coenzyme Q reductase (SQR) or respiratory complex II is an enzyme complex, found in many bacterial cells and in the inner mitochondrial membrane of eukaryotes. It is the only enzyme that participates in both the citric acid cycle and the electron transport chain. Histochemical analysis showing high succinate dehydrogenase in muscle demonstrates high mitochondrial content and high oxidative potential. In step 6 of the citric acid cycle, SQR catalyzes the oxidation of succinate to fumarate with the reduction of ubiquinone to ubiquinol. This occurs in the inner mitochondrial membrane by coupling the two reactions together. Structure Subunits Mitochondrial and many bacterial SQRs are composed of four structurally different subunits: two hydrophilic and two hydrophobic. The first two subunits, a flavoprotein (SdhA) and an iron-sulfur protein (SdhB), form a hydrophilic head where enzymatic activity of the complex takes place. Sdh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Calsequestrin
Calsequestrin is a calcium-binding protein that acts as a Calcium buffering, calcium buffer within the sarcoplasmic reticulum. The protein helps hold calcium in the cisterna of the sarcoplasmic reticulum after a muscle contraction, even though the concentration of calcium in the sarcoplasmic reticulum is much higher than in the cytosol. It also helps the sarcoplasmic reticulum store an extraordinarily high amount of calcium ions. Each molecule of calsequestrin can bind 18 to 50 Ca2+ ions. sequence (biology), Sequence analysis has suggested that calcium is not bound in distinct pockets via Ef hand motifs, EF-hand motifs, but rather via presentation of a charged protein surface. Two forms of calsequestrin have been identified. The cardiac form Calsequestrin-2 (CASQ2) is present in cardiac and slow skeletal muscle and the fast skeletal form Calsequestrin-1(CASQ1) is found in fast skeletal muscle. The release of calsequestrin-bound calcium (through a calcium release channel) trigger ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ATP2A1
Sarcoplasmic/endoplasmic reticulum calcium ATPase 1 (SERCA1) is an enzyme that in humans is encoded by the ''ATP2A1'' gene. Function This gene encodes one of the SERCA Ca2+-ATPases, which are intracellular pumps located in the sarcoplasmic or endoplasmic reticula of muscle cells. This enzyme catalyzes the hydrolysis of ATP coupled with the translocation of calcium from the cytosol to the sarcoplasmic reticulum lumen, and is involved in muscular excitation and contraction. Clinical significance Mutations in this gene cause some autosomal recessive forms of Brody disease, characterized by increasing impairment of muscular relaxation during exercise. Alternative splicing results in two transcript variants encoding different isoforms. Alternative splicing of ATP2A1 is also implicated in myotonic dystrophy type 1. ATP2A1 SERCA pumps were very strongly down regulated in amyotrophic lateral sclerosis. Interactions ATP2A1 has been shown to interact Advocates for Informed ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sarcoplasmic Reticulum
The sarcoplasmic reticulum (SR) is a membrane-bound structure found within muscle cells that is similar to the smooth endoplasmic reticulum in other Cell (biology), cells. The main function of the SR is to store calcium ions (Ca2+). Calcium in biology, Calcium ion levels are kept relatively constant, with the concentration of calcium ions within a cell being 10,000 times smaller than the concentration of calcium ions outside the cell. This means that small increases in calcium ions within the cell are easily detected and can bring about important cellular changes (the calcium is said to be a second messenger). Calcium is used to make calcium carbonate (found in chalk) and calcium phosphate, two compounds that the body uses to make teeth and bones. This means that too much calcium within the cells can lead to hardening (calcification) of certain intracellular structures, including the mitochondrion, mitochondria, leading to cell death. Therefore, it is vital that calcium ion levels a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Multi/minicore Myopathy
Multi/minicore myopathy is a congenital myopathy usually caused by mutations in either the ''SEPN1'' and ''RYR1'' genes. It is characterised the presence of multifocal, well-circumscribed areas with reduction of oxidative staining and low myofibrillar ATPase on muscle biopsy. It is also known as Minicore myopathy, Multicore myopathy, Multiminicore myopathy, Minicore myopathy with external ophthalmoplegia, Multicore myopathy with external ophthalmoplegia and Multiminicore disease with external ophthalmoplegia. Presentation There are four types of minicore myopathy Classical type (75% cases) The usual presentation is in infancy or childhood with hypotonia or proximal weakness. This weakness tends to affect the shoulder girdle and the inner thigh. The other main features are *Failure to thrive due to feeding difficulties * Axial muscle weakness, particularly affecting neck and trunk flexors * High pitched voice * Myopathic facial features A high arched or cleft palate may be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
RYR1
Ryanodine receptor 1 (RYR-1) also known as skeletal muscle calcium release channel or skeletal muscle-type ryanodine receptor is one of a class of ryanodine receptors and a protein found primarily in skeletal muscle. In humans, it is encoded by the ''RYR1'' gene. Function RYR1 functions as a calcium release channel in the sarcoplasmic reticulum, as well as a connection between the sarcoplasmic reticulum and the transverse tubule. RYR1 is associated with the dihydropyridine receptor (L-type calcium channels) within the sarcolemma of the T-tubule, which opens in response to depolarization, and thus effectively means that the RYR1 channel opens in response to depolarization of the cell. RYR1 plays a signaling role during embryonic skeletal myogenesis. A correlation exists between RYR1-mediated Ca2+ signaling and the expression of multiple molecules involved in key myogenic signaling pathways. Of these, more than 10 differentially expressed genes belong to the Wnt family which a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Malignant Hyperthermia
Malignant hyperthermia (MH) is a type of severe reaction that occurs in response to particular medications used during General anaesthesia, general anesthesia, among those who are susceptible. Symptoms include tetany, muscle rigidity, hyperthermia, fever, and a tachycardia, fast heart rate. Complications can include rhabdomyolysis, muscle breakdown and hyperkalemia, high blood potassium. Most people who are susceptible to MH are generally unaffected when not exposed to triggering agents. Exposure to triggering agents (certain inhalational anaesthetic, volatile anesthetic agents or Suxamethonium chloride, succinylcholine) can lead to the development of MH in those who are susceptible. Susceptibility can occur due to at least six genetic mutations, with the most common one being of the RYR1 gene. These genetic variations are often inherited from a person's parents in an Dominance (genetics), autosomal dominant manner. The condition may also occur as a new mutation or be associated w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
BIN1
Myc box-dependent-interacting protein 1, also known as Bridging Integrator-1 and Amphiphysin-2 is a protein that in humans is encoded by the ''BIN1'' gene. This gene encodes several isoforms of a nucleocytoplasmic adaptor protein, one of which was initially identified as a MYC-interacting protein with features of a tumor suppressor. Isoforms that are expressed in the central nervous system may be involved in synaptic vesicle endocytosis and may interact with dynanim, synaptojanin, endophilin, and clathrin. Isoforms that are expressed in muscle and ubiquitously expressed isoforms localize to the cytoplasm and nucleus and activate a caspase-independent apoptotic process. Studies in mouse suggest that this gene plays an important role in cardiac muscle development. Alternate splicing of the gene results in ten transcript variants encoding different isoforms. Aberrant splice variants expressed in tumor cell lines have also been described. Clinical significance In humans, mutations ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DNM2
Dynamin-2 is a protein that in humans is encoded by the ''DNM2'' gene. Function Dynamins represent one of the subfamilies of GTP-binding proteins. These proteins share considerable sequence similarity over the N-terminal portion of the molecule, which contains the GTPase domain. Dynamins are associated with microtubules. They have been implicated in cell processes such as endocytosis and cell motility, and in alterations of the membrane that accompany certain activities such as bone resorption by osteoclasts. Dynamins bind many proteins that bind actin and other cytoskeletal proteins. Dynamins can also self-assemble, a process that stimulates GTPase activity. Four alternatively spliced transcripts encoding different proteins have been described. Additional alternatively spliced transcripts may exist, but their full-length nature has not been determined. Interactions DNM2 has been shown to interact with: * SHANK1, * SHANK2, and * SNX9. Clinical relevance Mutations in thi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Autosomal Recessive
In genetics, dominance is the phenomenon of one variant (allele) of a gene on a chromosome masking or overriding the effect of a different variant of the same gene on the other copy of the chromosome. The first variant is termed dominant and the second recessive. This state of having two different variants of the same gene on each chromosome is originally caused by a mutation in one of the genes, either new (''de novo'') or inherited. The terms autosomal dominant or autosomal recessive are used to describe gene variants on non-sex chromosomes ( autosomes) and their associated traits, while those on sex chromosomes (allosomes) are termed X-linked dominant, X-linked recessive or Y-linked; these have an inheritance and presentation pattern that depends on the sex of both the parent and the child (see Sex linkage). Since there is only one copy of the Y chromosome, Y-linked traits cannot be dominant or recessive. Additionally, there are other forms of dominance such as incomplete d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
