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LAMA2-related muscular dystrophy is a disorder that causes weakness and wasting (atrophy) of muscles used for movement (skeletal muscles). This condition varies in severity, from a severe, early-onset type to a milder, late-onset form.

Early-onset LAMA2-related muscular dystrophy is apparent at birth or within the first few months of life. It is considered part of a class of muscle disorders called congenital muscular dystrophies and is sometimes called congenital muscular dystrophy type 1A. Affected infants may have severe muscle weakness, lack of muscle tone (hypotonia), little spontaneous movement, and joint deformities (contractures). Weakness of the muscles in the face and throat can result in feeding difficulties and an inability to grow and gain weight at the expected rate. Respiratory insufficiency, which occurs when muscles in the chest are weakened, causes a weak cry and breathing problems that can lead to frequent, potentially life-threatening lung infections.

Muscular Dystrophy Nedir

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As affected children grow, they often develop an abnormal, gradually worsening side-to-side curvature of the spine (scoliosis) and inward curvature of the back (lordosis). Children with early-onset LAMA2-related muscular dystrophy often do not develop the ability to walk. Difficulty with speech may result from weakness of the facial muscles and an enlarged tongue. Seizures occur in about a third of individuals with early-onset LAMA2-related muscular dystrophy; rarely, heart complications occur in this form of the disorder.

Symptoms of late-onset LAMA2-related muscular dystrophy become evident later in childhood or adulthood, and are similar to those of a group of muscle disorders classified as limb-girdle muscular dystrophies. In late-onset LAMA2-related muscular dystrophy, the muscles most affected are those closest to the body (proximal muscles), specifically the muscles of the shoulders, upper arms, pelvic area, and thighs. Children with late-onset LAMA2-related muscular dystrophy sometimes have delayed development of motor skills such as walking, but generally achieve the ability to walk without assistance. Over time, they may develop rigidity of the back, joint contractures, scoliosis, and breathing problems. However, most affected individuals retain the ability to walk and climb stairs.

The prevalence of LAMA2-related muscular dystrophy is estimated at between 1 in 50,000 and 1 in 400,000 individuals worldwide. This condition is thought to be the most common type of congenital muscular dystrophy, accounting for between 30 and 40 percent of total cases.

As its name suggests, LAMA2-related muscular dystrophy is caused by mutations in the LAMA2 gene. This gene provides instructions for making a part (subunit) of certain members of a protein family called laminins. Laminin proteins are made of three different subunits called alpha, beta, and gamma. There are several forms of each subunit, and each form is produced from instructions carried by a different gene. The LAMA2 gene provides instructions for the alpha-2 subunit. This subunit is found in the laminin 2 protein, also known as merosin; it is also part of another laminin protein called laminin 4.

Most LAMA2 gene mutations that cause the severe, early-onset form of LAMA2-related muscular dystrophy result in the absence of functional laminin alpha-2 subunit. Mutations that cause the milder, later-onset form usually result in a reduction (deficiency) of functional laminin alpha-2 subunit. Deficiency or absence of the laminin alpha-2 subunit results in a corresponding lack of laminin 2 and laminin 4, reducing the strength and stability of muscle tissue and leading to the signs and symptoms of LAMA2-related muscular dystrophy.

Fukuyama congenital muscular dystrophy is an inherited condition that predominantly affects the muscles, brain, and eyes. Congenital muscular dystrophies are a group of genetic conditions that cause muscle weakness and wasting (atrophy) beginning very early in life.

Fukuyama congenital muscular dystrophy affects the skeletal muscles, which are muscles the body uses for movement. The first signs of the disorder appear in early infancy and include a weak cry, poor feeding, and weak muscle tone (hypotonia). Weakness of the facial muscles often leads to a distinctive facial appearance including droopy eyelids (ptosis) and an open mouth. In childhood, muscle weakness and joint deformities (contractures) restrict movement and interfere with the development of motor skills such as sitting, standing, and walking.

Fukuyama congenital muscular dystrophy also impairs brain development. People with this condition have a brain abnormality called cobblestone lissencephaly, in which the surface of the brain develops a bumpy, irregular appearance (like that of cobblestones). These changes in the structure of the brain lead to significantly delayed development of speech and motor skills and moderate to severe intellectual disability. Social skills are less severely impaired. Most children with Fukuyama congenital muscular dystrophy are never able to stand or walk, although some can sit without support and slide across the floor in a seated position. More than half of all affected children also experience seizures.

Other signs and symptoms of Fukuyama congenital muscular dystrophy include impaired vision, other eye abnormalities, and slowly progressive heart problems after age 10. As the disease progresses, affected people may develop swallowing difficulties that can lead to a bacterial lung infection called aspiration pneumonia. Because of the serious medical problems associated with Fukuyama congenital muscular dystrophy, most people with the disorder live only into late childhood or adolescence.

Fukuyama congenital muscular dystrophy is seen almost exclusively in Japan, where it is the second most common form of childhood muscular dystrophy (after Duchenne muscular dystrophy). Fukuyama congenital muscular dystrophy has an estimated incidence of 2 to 4 per 100,000 Japanese infants.

Fukuyama congenital muscular dystrophy is caused by mutations in the FKTN gene. This gene provides instructions for making a protein called fukutin. Although the exact function of fukutin is unclear, researchers predict that it may chemically modify a protein called alpha ()-dystroglycan. This protein anchors cells to the lattice of proteins and other molecules (the extracellular matrix) that surrounds them. In skeletal muscles, -dystroglycan helps stabilize and protect muscle fibers. In the brain, this protein helps direct the movement (migration) of nerve cells (neurons) during early development.

Defective -dystroglycan also affects the migration of neurons during the early development of the brain. Instead of stopping when they reach their intended destinations, some neurons migrate past the surface of the brain into the fluid-filled space that surrounds it. Researchers believe that this problem with neuronal migration causes cobblestone lissencephaly in children with Fukuyama congenital muscular dystrophy. Less is known about the effects of FKTN mutations in other parts of the body.

Myotonic dystrophy (DM) is a type of muscular dystrophy, a group of genetic disorders that cause progressive muscle loss and weakness.[1] In DM, muscles are often unable to relax after contraction.[1] Other manifestations may include cataracts, intellectual disability and heart conduction problems.[1][2] In men, there may be early balding and an inability to father children.[1] While myotonic dystrophy can occur at any age, onset is typically in the 20s and 30s.[1]

Myotonic dystrophy is caused by a genetic mutation in one of two genes. Mutation of the DMPK gene causes myotonic dystrophy type 1 (DM1). Mutation of CNBP gene causes type 2 (DM2).[1] DM is typically inherited, following an autosomal dominant inheritance pattern,[1] and it generally worsens with each generation.[1] A type of DM1 may be apparent at birth.[1] DM2 is generally milder.[1] Diagnosis is confirmed by genetic testing.[2]

Myotonic dystrophy affects about 1 in 2,100 people,[4] a number that was long estimated to be much lower (often cited as 1 in 8,000), reflecting that not all patients have immediate symptoms and, once they do have symptoms, the long time it typically takes to get to the right diagnosis.[1] It is the most common form of muscular dystrophy that begins in adulthood.[1] It was first described in 1909, with the underlying cause of type 1 determined in 1992.[2]

DM causes muscle weakness, early onset of cataracts, and myotonia, which is delayed relaxation of muscles after contraction.[5] Cataracts can be either a cortical cataract with a blue dot appearance, or a posterior subcapsular cataract.[6] Other organs affected include the heart, lungs, gastrointestinal tract, skin, and brain.[5] Insulin resistance can also occur.[5] Signs and symptoms vary considerably by severity, unusual phenotype, and form (DM1/DM2).[citation needed] DM1 and DM2 differ in regards to the muscles they affect, age of onset, severity of disease, and extramuscular manifestations.[5]

Myotonic dystrophy (DM) is a genetic condition that is inherited in an autosomal dominant pattern, meaning each child of an affected individual has a 50% chance of inheriting the disease. The mutation involves satellite DNA, which is tandemly repeated sequences of DNA that do not code for a protein. The repeats implicated in myotonic dystrophy are either 3 or 4 nucleotides in length, classified as microsatellites. Disease results from an abnormally increased number of these microsatellites, termed microsatellite expansion.

The microsatellite expansion responsible for DM1 is of cytosine-thymine-guanine (CTG) triplet repeats, termed trinucleotide repeat expansion and classifying DM1 as a one of several trinucleotide repeat disorders. This expansion occurs at the end of the DMPK gene, in the 3' untranslated region. DMPK is located on the long arm of chromosome 19.[10][11] DMPK codes for myotonic dystrophy protein kinase,[12] a protein expressed predominantly in skeletal muscle.[13] 006ab0faaa