A glycogen storage disease is a metabolic disorder caused by a deficiency of an enzyme or transport protein affecting glycogen synthesis, glycogen breakdown, or glucose breakdown, typically in muscles and/or liver cells.
Arthrogryposis (AMC) describes congenital joint contracture in two or more areas of the body. It derives its name from Greek, literally meaning 'curving of joints'.
Hypotonia is a state of low muscle tone, 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 nature of the cause. Some disorders have a specific treatment but the principal treatment for most hypotonia of idiopathic or neurologic cause is physical therapy and/or occupational therapy for remediation.
In medicine, myopathy is a disease of the muscle in which the muscle fibers do not function properly. Myopathy means muscle disease. This meaning implies that the primary defect is within the muscle, as opposed to the nerves or elsewhere.
Nemaline myopathy is a congenital, often hereditary neuromuscular disorder with many symptoms that can occur such as muscle weakness, hypoventilation, swallowing dysfunction, and impaired speech ability. The severity of these symptoms varies and can change throughout one's life to some extent. The prevalence is estimated at 1 in 50,000 live births. It is the most common non-dystrophic myopathy.
Mitochondrial myopathies are types of myopathies associated with mitochondrial disease. Adenosine triphosphate (ATP), the chemical used to provide energy for the cell, cannot be produced sufficiently by oxidative phosphorylation when the mitochondrion is either damaged or missing necessary enzymes or transport proteins. With ATP production deficient in mitochondria, there is an over-reliance on anaerobic glycolysis which leads to lactic acidosis either at rest or exercise-induced.
Centronuclear myopathies (CNM) are a group of congenital myopathies where cell nuclei are abnormally located in the center of muscle cells instead of their normal location at the periphery.
Congenital muscular dystrophies are autosomal recessively-inherited muscle diseases. They are a group of heterogeneous disorders characterized by muscle weakness which is present at birth and the different changes on muscle biopsy that ranges from myopathic to overtly dystrophic due to the age at which the biopsy takes place.
Emery–Dreifuss muscular dystrophy (EDMD) is a type of muscular dystrophy, a group of heritable diseases that cause progressive impairment of muscles. EDMD affects muscles used for movement, causing atrophy, weakness and contractures. It almost always affects the heart, causing abnormal rhythms, heart failure, or sudden cardiac death. It is rare, affecting 0.39 per 100,000 people. It is named after Alan Eglin H. Emery and Fritz E. Dreifuss.
Distal myopathy is a group of rare genetic disorders that cause muscle damage and weakness, predominantly in the hands and/or feet. Mutation of many different genes can be causative. Many types involve dysferlin.
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:
Bethlem myopathy is predominantly an autosomal dominant myopathy, classified as a congenital form of limb-girdle muscular dystrophy. There are two types of Bethlem myopathy, based on which type of collagen is affected.
Central core disease (CCD), also known as central core myopathy, is an autosomal dominant inherited muscle disorder present from birth that negatively affects the skeletal muscles. It was first described by Shy and Magee in 1956. It is characterized by the appearance of the myofibril under the microscope.
Ullrich congenital muscular dystrophy (UCMD) is a form of congenital muscular dystrophy. There are two forms: UCMD1 and UCMD2.
Collagen VI (ColVI) is a type of collagen primarily associated with the extracellular matrix of skeletal muscle. ColVI maintains regularity in muscle function and stabilizes the cell membrane. It is synthesized by a complex, multistep pathway that leads to the formation of a unique network of linked microfilaments located in the extracellular matrix (ECM). ColVI plays a vital role in numerous cell types, including chondrocytes, neurons, myocytes, fibroblasts, and cardiomyocytes. ColVI molecules are made up of three alpha chains: α1(VI), α2(VI), and α3(VI). It is encoded by 6 genes: COL6A1, COL6A2, COL6A3, COL6A4, COL6A5, and COL6A6. The chain lengths of α1(VI) and α2(VI) are about 1,000 amino acids. The chain length of α3(VI) is roughly a third larger than those of α1(VI) and α2(VI), and it consists of several spliced variants within the range of 2,500 to 3,100 amino acids.
Multi/minicore myopathy is a congenital myopathy usually caused by mutations in either the SELENON 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.
Congenital distal spinal muscular atrophy (cDSMA), also known as distal hereditary motor neuropathytype VIII (dHMN8), is a hereditary medical condition characterized by muscle wasting (atrophy), particularly of distal muscles in legs and hands, and by early-onset contractures of the hip, knee, and ankle. Affected individuals often have shorter lower limbs relative to the trunk and upper limbs. The condition is a result of a loss of anterior horn cells localized to lumbar and cervical regions of the spinal cord early in infancy, which in turn is caused by a mutation of the TRPV4 gene. The disorder is inherited in an autosomal dominant manner. Arm muscle and function, as well as cardiac and respiratory functions are typically well preserved.
Muscle–eye–brain (MEB) disease, also known as muscular dystrophy-dystroglycanopathy congenital with brain and eye anomalies A3 (MDDGA3), is a kind of rare congenital muscular dystrophy (CMD), largely characterized by hypotonia at birth. Patients have muscular dystrophy, central nervous system abnormalities and ocular abnormalities. The condition is degenerative.
Calpainopathy is the most common type of autosomal recessive limb-girdle muscular dystrophy (LGMD). It preferentially affects the muscles of the hip girdle and shoulder girdle.
Compton-North congenital myopathy, also known as congenital lethal myopathy, Compton-North type, is a rare, fatal genetic disorder of pre-natal onset that results in death shortly after birth and is characterized by fetal akinesia and movement restriction, polyhydramnios, severe hypotonia of neonatal-onset, generalized weakness of the respiratory, bulbar, and skeletal muscles, presence of multiple congenital muscular contractures.
