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Muscular dystrophies are a group of genetic conditions characterized by progressive muscle weakness and wasting. Duchenne and Becker types of muscular dystrophy are two related conditions that primarily affect skeletal muscles, which are used for movement, and heart muscle. These forms of muscular dystrophy occur almost exclusively in males. Duchenne and Becker muscular dystrophies have similar signs and symptoms and are caused by different mutations in the same gene. Two conditions differ in their severity, age of onset, and rate of progression. In boys with Duchenne muscular dystrophy, muscle weakness tends to appear in early childhood and worsen rapidly. Affected children may have delayed motor skills, such as sitting, standing, and walking. They are usually wheelchair - dependent by adolescence. Signs and symptoms of Becker muscular dystrophy are usually milder and more varied. In most cases, muscle weakness becomes apparent later in childhood or in adolescence and worsens at a much slower rate. Both the Duchenne and Becker forms of muscular dystrophy are associated with a heart condition called cardiomyopathy. This form of heart disease weakens cardiac muscle, preventing the heart from pumping blood efficiently. In both Duchenne and Becker muscular dystrophy, cardiomyopathy typically begins in adolescence. Later, heart muscle becomes enlarge, and heart problems develop into a condition known as dilated cardiomyopathy. Signs and symptoms of dilated cardiomyopathy can include irregular heartbeat, shortness of breath, extreme tiredness, and swelling of legs and feet. These heart problems worsen rapidly and become life - threatening in most cases. Males with Duchenne muscular dystrophy typically live into their twenties, while males with Becker muscular dystrophy can survive into their forties or beyond. A related condition called X - link dilated cardiomyopathy is a form of heart disease caused by mutations in the same gene as Duchenne and Becker muscular dystrophy, and it is sometimes classified as subclinical Becker muscular dystrophy. People with X - link dilate cardiomyopathy typically do not have any skeletal muscle weakness or wasting, although they may have subtle changes in their skeletal muscle cells that are detectable through laboratory testing. Mutations in DMD gene cause Duchenne and Becker forms of muscular dystrophy. The DMD gene provides instructions for making a protein called dystrophin. This protein is located primarily in skeletal and cardiac muscle, where it helps stabilize and protect muscle fibers. Dystrophin may also play a role in chemical signaling within cells. Mutations in DMD gene alter the structure or function of dystrophin or prevent any functional dystrophin from being produce. Muscle cells without enough of this protein become damaged as muscles repeatedly contract and relax with use. Damage fibers weaken and die over time, leading to muscle weakness and heart problems characteristic of Duchenne and Becker muscular dystrophies. Mutations that lead to abnormal version of dystrophin that retains some function usually cause Becker muscular dystrophy, while mutations that prevent production of any functional dystrophin tend to cause Duchenne muscular dystrophy. Because Duchenne and Becker muscular dystrophies result from faulty or missing dystrophin, these conditions are classified as dystrophinopathies.
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Duchenne Muscular Dystrophy is a genetic disorder characterized by progressive muscle degeneration and weakness due to alterations of protein called dystrophin that helps keep muscle cells intact. Dmd is one of four conditions known as dystrophinopathies. Other three Diseases that belong to this group are Becker Muscular Dystrophy; intermediate clinical presentation between DMD and BMD; and DMD - associate dilate cardiomyopathy with little or no clinical skeletal, or voluntary, muscle disease. Dmd symptom onset is in early childhood, usually between ages 2 and 3. The disease primarily affects boys, but in rare cases it can affect girls. In Europe and North America, prevalence of DMD is approximately 6 per 100 000 individuals. 1 234 muscle weakness is the principal symptom of DMD. It can begin as early as age 2 or 3, first affecting proximal muscles and later affecting distal limb muscles. Usually, lower external muscles are affected before upper external muscles. Affect children might have difficulty jumping, running, and walking. Other symptoms include enlargement of calves, waddling gait, and lumbar lordosis. Later on, heart and respiratory muscles are affected as well. Progressive weakness and scoliosis result in impaired pulmonary function, which can eventually cause acute respiratory failure. For more about DMD symptoms, see Signs and Symptoms. Becker Muscular Dystrophy is similar to DMD, but with onset usually in teens or early adulthood. The disease course for BMD is slower and less predictable compared to DMD. Dmd was first described by French neurologist Guillaume Benjamin Amand Duchenne in the 1860s, but until the 1980s, little was known about the cause of any kind of Muscular Dystrophy. In 1986, MDA - support researchers identified a particular gene on the X chromosome that, when flaw, leads to DMD. In 1987, protein associated with this gene was identified and named dystrophin. Lack of dystrophin protein in muscle cells causes them to be fragile and can easily damage. Dmd has an X - link recessive Inheritance pattern and is passed on by the mother, who is referred to as carrier. For more about way gene mutations cause DMD, see Causes / Inheritance. Dmd carriers are females who have normal dystrophin gene on one X chromosome and abnormal dystrophin gene on other X chromosome. Most carriers of DMD do not themselves have signs and symptoms of disease, but a minority do. Symptoms can range from mild skeletal muscle weakness or cardiac involvement to severe weakness or cardiac effects and can begin in childhood or adulthood. For more, read Females and DMD in Causes / Inheritance. Until relatively recently, boys with DMD usually do not survive much beyond their teen years. Thanks to advances in cardiac and respiratory care, life expectancy is increasing and many young adults with DMD attend college, have careers, get marry, and have children. Survival into early 30s is becoming more common than before. For more about living with DMD, see Medical Management.
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Complications of Muscular Dystrophy depend on type. Some types are mild, while others are serious and get worse very fast. Worsening muscle weakness can affect the ability to walk, breathe, swallow, and speak. Breathing Problems. Progressive weakness in breathing muscles makes it hard to take breath. That raises the risk for lung infections such as pneumonia. Curving of spine. Weakness in muscles supporting the backbone causes the spine to become curve. Most people with Duchenne Muscular Dystrophy need scoliosis surgery. Heart Problems. Some types of Muscular Dystrophy cause abnormal and dangerous changes in heartbeat. You need a pacemaker to regulate it. Muscular Dystrophy can also cause heart muscle to become weak. That leads to heart failure. Swallowing Difficulty. Weakness affects muscles in the esophagus, and causes problems with chewing and swallowing. This can lead to choking. Some people with Muscular Dystrophy will need feeding tube. Shortening of tendons or muscles around joints. Bracing and tendon release surgery can help prevent some contractures. Vision Problems. Some types of Muscular Dystrophy cause clouding of eye lenses. I need a wheelchair. Weakness in large muscles of legs makes it difficult to walk, stand, kneel, or climb. Some people with Muscular Dystrophy eventually need to use a wheelchair.
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Congenital muscular Dystrophy refers to a group of muscular dystrophies that become apparent at or near birth. Muscular dystrophies in general ARE GENETIC, degenerative diseases primarily affecting voluntary muscles. For more on specific types OF CMD, see Types OF CMD. Cmd results in overall MUSCLE weakness with possible joint stiffness or looseness. Depending on type, CMD may involve spinal curvature, respiratory insufficiency, intellectual disabilities, learning disabilities, eye defects or seizures. For more, see Types OF CMD and Signs and Symptoms. Cmd is caused by GENETIC mutations affecting some OF PROTEINS necessary FOR muscles and sometimes FOR the eyes and or brain. See cause / Inheritance. Cmd has its onset at or near birth, and progression varies by type. Many types ARE slowly progressive; some shorten life span. Researchers have identified many OF genes THAT, when DEFECTIVE, cause various FORMS OF CMD. These discoveries have led to greater understanding of these diseases and advances in diagnosis and treatment strategies. For more, see Research. Congenital muscular Dystrophy is the general term FOR group OF GENETIC MUSCLE diseases that occur at birth or early during infancy. Cmds ARE generally characterized by diminished MUSCLE tone, which is sometimes referred TO AS floppy baby; progressive MUSCLE weakness and degeneration; abnormally fixed joints that occur when thickening and shortening OF tissue such AS MUSCLE FIBERS causes deformity and restricted movement OF affected area; spinal rigidity, and delays in reaching motor milestones such AS sitting or standing unassisted. Feeding difficulties and breathing complications can develop in some cases. Muscle weakness may improve, remain stable or worsen. Some FORMS OF CMD may be associated with STRUCTURAL brain defects and, potentially, intellectual disability. Severity, specific symptoms, and progression of these disorders vary greatly. Most FORMS OF CMD ARE inherited autosomal recessive traits. College type VI - related disorders can be inherited AS either autosomal dominant or autosomal recessive conditions. Lmna - related CMD is inherited in an autosomal dominant manner, WITH all mutations reported TO date being new mutations. Cmds belong to a larger group of disorders known as AS muscular dystrophies. Muscular dystrophies are characterized by weakness and degeneration of various voluntary muscles of the body. More than 30 different disorders make up muscular dystrophies. Disorders affect different muscles and have different ages OF onset, severity and inheritance patterns. As researchers have learnt more about CMDS, such AS identifying many specific genes involve, broader picture of these diseases has emerge. Subtypes OF CMD have considerable overlap with other disease classifications, including congenital myopathies, disorders OF glycosylation, and limb - girdle muscular dystrophies. Cmds ARE rapidly growing disease family and information about these disorders is constantly changing.
Duchenne Muscular Dystrophy is a form of Muscular Dystrophy. It worsens quickly. Other Muscular Dystrophies get worse much more slowly. Duchenne Muscular Dystrophy is caused by a defective gene for dystrophin. However, it often occurs in people without know family history of condition. Conditions most often affect boys due to the way disease is inherit. Sons of women who are carriers of disease each have a 50% chance of having the disease. Daughters each have a 50% chance of being carriers. Very rarely, females are affected by disease. Duchenne Muscular Dystrophy occurs in about 1 out of every 3600 male infants. Because this is an inherited disorder, risks include a family history of Duchenne Muscular Dystrophy. There is no known cure for Duchenne Muscular Dystrophy. Treatment aims to control symptoms to improve the quality of life. Steroid drugs can slow loss of muscle strength. They may start when a child is diagnosed or when muscle strength begins to decline. Albuterol, drug used for people with asthma Amino acids Carnitine Coenzyme Q10, Creatine, fish oil, Green tea extract Vitamin E. However, effects of these treatments have not been proven. Stem cells and gene therapy may be used in the future. Use of steroids and lack of physical activity can lead to excessive weight gain. Activity is encourage. Inactivity can make muscle disease worse. Physical therapy may help to maintain muscle strength and function. Speech therapy is often needed Assist ventilation drugs to help heart function, such as angiotensin converting enzyme inhibitors, beta blockers, and diuretics, Orthopedic appliances to improve mobility, Spine surgery to TREAT progressive scoliosis for some people, Proton pump inhibitors
Corticosteroids, such as prednisone and deflazacort, can help muscle strength and delay progression of certain types of muscular dystrophy. But prolonged use of these types of drugs can cause weight gain and weaken bones, increasing fracture risk. Newer drugs include eteplirsen, first medication to be approved by the Food and Drug Administration specifically to treat some people with Duchenne muscular dystrophy. It was conditionally approved in 2016. In 2019, FDA will approve golodirsen for treatment of some people with Duchenne dystrophy who have certain genetic mutation. Heart medications, such as angiotensin - converting enzyme inhibitors or beta blockers, if muscular dystrophy damages the heart.
Doctors may recommend that some MD patients have surgery to improve or correct problems stemming from their condition. When muscles involved in breathing start to weaken, patients may need assisted ventilation to help maintain sufficient air flow in and out of lungs. Initially, patient may be given a noninvasive device, such as a mask, nosepiece, or mouthpiece. But a type of surgery called tracheostomy may be recommended in later stages of disease. This involves making a small opening in the neck so tube can be inserted directly into the windpipe, or trachea. The tube can then be connected to a device to supply oxygen as necessary. Problems swallowing caused by MD can lead to patients getting insufficient nutrition. If this continue, doctors may recommend implanting a feeding tube that delivers nutrients directly into the stomach, through a procedure called gastrostomy. Other types of surgeries that MD patients may need include: fitting pacemaker to treat heart problems. Surgery to remove cataracts. Surgery to correct the curvature of the spine, such as scoliosis or kyphosis. * Muscular Dystrophy News is strictly news and information website about disease. It does not provide medical advice, diagnosis, or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek advice of your physician or other qualified health provider with any questions you may have regarding medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.
To start, your doctor will examine your child and ask questions about medical and family health history. Muscular dystrophy is diagnosed using several different tests. These may include: muscle biopsy. A small piece of muscle tissue is removed and examined to confirm diagnosis or rule out another muscle disease. Genetic testing. Genes passed down through families can cause some forms of muscular dystrophy. Blood tests can determine if you or your child has gene. Neurological tests. Various tests are done to check nervous system function, reflexes, and coordination. One example is nerve conduction study, also called nerve function test, or electromyography.
Although there's no cure for any form of Muscular Dystrophy, treatment for some forms of disease can help extend time person with disease can remain mobile and help with heart and lung muscle strength. Trials of new therapies are ongoing. People with Muscular Dystrophy should be monitored throughout their lives. Their care team should include a neurologist with expertise in neuromuscular diseases, physical medicine and rehabilitation specialist, and physical and occupational therapists. Some people might also need a lung specialist, heart specialist, cardiologist, sleep specialist, specialist in endocrine system, orthopedic surgeon and other specialists. Treatment options include medications, physical and occupational therapy, and surgical and other procedures. Ongoing assessments of walking, swallowing, breathing and hand function enable the treatment team to adjust treatments as disease progress. Corticosteroids, such as prednisone and deflazacort, can help muscle strength and delay progression of certain types of Muscular Dystrophy. But prolonged use of these types of drugs can cause weight gain and weaken bones, increasing fracture risk. Newer drugs include eteplirsen, first medication to be approved by the Food and Drug Administration specifically to treat some people with Duchenne Muscular Dystrophy. It was conditionally approved in 2016. In 2019, FDA approved golodirsen for treatment of some people with Duchenne Dystrophy who have certain genetic mutation. Heart medications, such as angiotensin - converting enzyme inhibitors or beta blockers, if Muscular Dystrophy damages the heart. Several types of therapy and assistive devices can improve the quality and sometimes length of life in people who have Muscular Dystrophy. Examples include: range - of - motion and stretching exercises. Muscular Dystrophy can restrict flexibility and mobility of joints. Limbs often draw inward and become fixed in that position. Range - of - motion exercises can help to keep joints as flexible as possible. Exercise. Low - impact aerobic exercise, such as walking and swimming, can help maintain strength, mobility and general health. Some types of strengthening exercises also might be helpful. But it's important to talk to your doctor first because some types of exercise might be harmful. Braces. Braces can help keep muscles and tendons stretched and flexible, slowing progression of contractures. Braces can also aid mobility and function by providing support for weakened muscles. Mobility aids. Canes, walkers and wheelchairs can help maintain mobility and independence. Breathing assistance. As respiratory muscles weaken, sleep apnea device might help improve oxygen delivery during the night. Some people with severe Muscular Dystrophy need to use a machine that forces air in and out of their lungs. Surgery might be needed to correct contractures or spinal curvature that could eventually make breathing more difficult. Heart function may be improved with a pacemaker or other cardiac device. Respiratory infections can become a problem in Muscular Dystrophy. So, it's important to be vaccinated for pneumonia and to keep up to date with influenza shots. Try to avoid contact with children or adults who have obvious infection.
Both an individual's medical history and complete family history should be thoroughly reviewed to determine if muscle disease is secondary to disease affecting other tissues or organs or is an inherited condition. It is also important to rule out any muscle weakness resulting from prior surgery, exposure to toxins, or current medications that may affect a person's functional status or rule out many acquire muscle diseases. Thorough clinical and neurological exams can rule out disorders of central and / or peripheral nervous systems, identify any patterns of muscle weakness and atrophy, test reflex responses and coordination, and look for contractions. Various laboratory tests may be used to confirm the diagnosis of MD. Blood and urine tests can detect defective genes and help identify specific neuromuscular disorders. For example: creatine kinase is an enzyme that leaks out of damaged muscle. Elevate creatine kinase levels may indicate muscle damage, including some forms of MD, before physical symptoms become apparent. Levels are significantly increase in the early stages of Duchenne and Becker MD. Testing can also determine if a young woman is carrier of a disorder. The level of serum aldolase, enzyme involved in breakdown of glucose, is measure to confirm diagnosis of skeletal muscle disease. High levels of enzyme, which are present in most body tissues, are noted in people with MD and some forms of myopathy. Myoglobin is a measure when injury or disease in skeletal muscle is suspect. Myoglobin is an oxygen - binding protein found in cardiac and skeletal muscle cells. High blood levels of myoglobin are found in people with MD. Polymerase chain reaction can detect some mutations in dystrophin gene. Also known as molecular diagnosis or genetic testing, PCR is a method for generating and analyzing multiple copies of fragment of DNA. Serum electrophoresis is a test to determine quantities of various proteins in a person's DNA. Blood sample is placed on specially treated paper and exposed to electric current. Charge forces different proteins to form bands that indicate the relative proportion of each protein fragment. Exercise tests can detect elevated rates of certain chemicals following exercise and are used to determine the nature of MD or other muscle disorder. Some exercise tests can be performed at bedside while others are done at clinics or other sites using sophisticated equipment. These tests also assess muscle strength. They are performed when a person is relaxed and in proper position to allow technicians to measure muscle function against gravity and detect even slight muscle weakness. If weakness in respiratory muscles is suspect, respiratory capacity may be measured by having a person take deep breath and count slowly while exhaling. Genetic testing looks for genes known to either cause or be associated with inherited muscle disease. Dna analysis and enzyme assays can confirm diagnosis of certain neuromuscular diseases, including MD. Genetic linkage studies can identify whether specific genetic markers on chromosome and disease are inherited together.
The National Institute of Neurological Disorders and Stroke, part of the National Institutes of Health, supports a broad program of research on MD. The goals of these studies are to increase understanding of MD and its causes, develop better therapies, and, ultimately, find ways to treat it. Ninds and its sister Institutes, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institute of Child Health and Human Development, and National Heart, Blood, and Lung Institute, lead MD Research efforts conducted at NIH and at grantee institutions throughout the country. Nih supports a broad range of basic, translational, and clinical research in MDs. Advances in basic research are essential to basic understanding of each type of MD. While many genes that cause Muscular Dystrophy still remain to be identify, advances in gene sequencing have aided identification of genes that may be involved in most types of Muscular Dystrophy. In turn, new knowledge of specific disease mechanisms is identifying potential targets for therapy development. In recent years, research into underlying disease mechanisms has created new opportunities for therapy development in nearly all types of MD. For example, advances in targeted therapy have led to promising efforts in myotonic Dystrophy and facioscapulohumeral Muscular Dystrophy. Federal funding, through NIH and other agencies, as well as venture philanthropy programs supported by patient advocacy groups, have attracted biotechnology and pharmaceutical firm investments into therapies for MDs. Currently, variety of strategies are employed in developing new drugs and biologic therapies for a range of MDs. Strategies being explored are either specific to particular type of MD or may address disease progression that may apply to multiple types of MD. Gene replacement therapy Gene therapy has potential for directly addressing the primary cause of MD by providing for production of missing protein. Hurdles to be overcome include determining timing of therapy, avoiding or easing potential immune responses to replacement gene, and, in the case of Duchenne MD, large size of gene to be replace. For those MDs with central nervous system consequences, researchers are developing and fine - tuning gene therapy vectors that can cross the protective Blood - brain barrier. Recent progress in delivery of replacement genes in MD includes considerable refinement of viral vector types that improve targeting to skeletal muscle and vascular approaches to deliver replacement genes to most or all skeletal muscles. Approaches that work for skeletal muscles may or may not work for cardiac muscle; this is a challenge that must be met since many MDs cause cardiomyopathy. Strategies for assessing potential immune responses to proteins encoded by replacement genes and for managing those responses also have received considerable attention in in animal model studies and in human clinical trials. Finally, for some MDs, early detection of disease causing mutations, through newborn screening, may be necessary for Gene replacement therapy to be used early enough to mitigate progression of disease.
Duchenne Muscular Dystrophy is a genetic disorder characterized by progressive muscle degeneration and weakness due to alterations of protein called dystrophin that helps keep muscle cells intact. Dmd is one of four conditions known as dystrophinopathies. The other three Diseases that belong to this group are Becker Muscular Dystrophy; intermediate clinical presentation between DMD and BMD; and DMD - associate dilate cardiomyopathy with little or no clinical skeletal, or voluntary, muscle disease. Dmd symptom onset is in early childhood, usually between ages 2 and 3. The disease primarily affects boys, but in rare cases it can affect girls. In Europe and North America, prevalence of DMD is approximately 6 per 100 000 individuals.
This disorder manifests typically between 2 and 3 years of age. Weakness affects proximal muscles, typically in the lower limbs initially. Children frequently toe walk and have waddling gait and lordosis. They have difficulty running, jumping, climbing stairs, and rising from the floor. Children fall frequently, often causing arm or leg fractures. Progression of weakness is steady, and limb flexion contractures and scoliosis develop in nearly all children. Firm pseudohypertrophy develop. Most children need to use a wheelchair by age 12 and die of respiratory complications by age 20. No specific treatment exists. Gentle active exercise is encouraged for as long as possible to avoid disuse atrophy or complications of inactivity. Passive exercises may extend the period of ambulation. Orthopedic interventions should be aimed at maintaining function and preventing contractures. Ankle - foot orthoses worn during sleep may help prevent flexion contractures. Leg braces may temporarily help preserve ambulation or standing. Corrective surgery is sometimes needed, particularly for scoliosis. Obesity should be avoid; caloric requirements are likely to be less than normal because of decreased physical activity. In Duchenne dystrophy, daily prednisone or deflazacort is considered for patients under age 5 years who are no longer gaining or have declining motor skills. These drugs start working as early as 10 days after initiation of therapy; efficacy peaks at 3 months and persists for 6 months. Long - term use improves strength, delays the age at which ambulation is lost by 1. 4 to 2. 5 years, improves timed function testing, improves pulmonary function, reduces orthopedic complications, stabilizes cardiac function, and increases survival by 5 to 15 years. Alternate - day prednisone is not effective. Weight gain and cushingoid facies are common adverse effects after 6 to 18 months. The risk of vertebral compression and long bone fractures also increase. Deflazacort may be associated with a greater risk of cataracts than prednisone. Use of prednisone or deflazacort in Becker's dystrophy has not been adequately study. Exon - skipping therapies have been approved for the treatment of Duchenne dystrophy. Two such therapies are eteplirsen and golodirsen. These drugs are called antisense oligonucleotides and work like molecular patches to abnormal dystrophin genes in which one or more exons are missing. Drugs mask exon so that it will be skipped and ignored during protein production, allowing production of dystrophin protein that, while not normal, is functional and may lessen symptoms so that they are more like those in boys with less severe Becker muscular dystrophy. Eteplirsen skips exon 51. Limit data suggest that eteplirsen leads to increased dystrophin in muscle and increased walking performance on timed tests in 13% of patients with Duchenne dystrophy who have dystrophin gene mutation that is amenable to exon 51 skipping. The drug's approval has been criticized because it was based on a small trial that relied on surrogate outcome, and clinical benefits remain unproved. The recommended dosage of eteplirsen is 30 mg / kg IV infusion over 35 to 60 minutes once a week.
Myotonic DYSTROPHY is part of a group of inherited disorders called muscular dystrophies. It is the most common form of muscular DYSTROPHY that begins in adulthood. Myotonic DYSTROPHY is characterized by progressive muscle wasting and weakness. People with this disorder often have prolonged muscle contractions and are not able to relax certain muscles after use. For example, person may have difficulty releasing their grip on doorknob or handle. Also, affected people may have slur speech or temporary locking of their jaw. Other Signs and Symptoms of MYOTONIC DYSTROPHY include clouding of lens of eye and abnormalities of electrical signals that control heartbeat. Some affected individuals develop a condition called diabetes mellitus, in which blood sugar levels can become dangerously high. Features of MYOTONIC DYSTROPHY often develop during a person's twenties or thirties, although they can occur at any age. The severity of condition varies widely among affected people, even among members of the same family. There are two major types of MYOTONIC DYSTROPHY: TYPE 1 and TYPE 2. Their signs and symptoms overlap, although TYPE 2 tends to be milder than TYPE 1. Muscle weakness associated with TYPE 1 particularly affects muscles farthest from the center of the body, such as those of lower legs, hands, neck, and face. Muscle weakness in TYPE 2 primarily involves muscles close to the center of the body, such as those of the neck, shoulders, elbows, and hips. Two types of MYOTONIC DYSTROPHY are caused by mutations in different genes. There are two variations of MYOTONIC DYSTROPHY TYPE 1: Mild and CONGENITAL types. Mild MYOTONIC DYSTROPHY is apparent in mid to late adulthood. Affected individuals typically have Mild Myotonia and cataracts. Congenital MYOTONIC DYSTROPHY is often apparent at birth. Characteristic features include weak muscle tone, inward - and upward - turning foot, breathing problems, delayed development, and intellectual disability. Some of these health problems can be life - threatening. Both types of MYOTONIC DYSTROPHY are inherited in autosomal dominant pattern, which means one copy of altered gene in each cell is sufficient to cause disorder. In most cases, affected person has one parent with condition. As MYOTONIC DYSTROPHY is passed from one generation to the next, disorder generally begins earlier in life and signs and symptoms become more severe. This phenomenon is called anticipation. Evidence for anticipation appears only in MYOTONIC DYSTROPHY TYPE 1. In this form of disorder, anticipation is caused by an increase in length of unstable region in DMPK gene. Longer unstable regions in CNBP gene do not appear to influence the age of ONSET of MYOTONIC DYSTROPHY TYPE 2.
|LGMD1B||LMNA 9 , 10||Most common autosomal dominant type, accounts for 5-10% of all cases|
|LGMD1C||CAV3 7 , 11|
|LGMD1D||DNAJB6 12 , 13|
|LGMD1G||HNRNPDL 16 , 17|
Limb - Girdle Muscular Dystrophy is the name given to a varied collection of neuromuscular disorders with different genetic causes. Limb - Girdle is a bony structure surrounding shoulder and hip joints. Lgmd is characterized by muscle atrophy in Limb - Girdle regions of the body, or in muscles around shoulders and hips. Estimates of the incidence of LGMD range from one in 14 500 to one in 123 000 people. Lgmd isA divided into two groups, LGMD1 and LGMD2, based on disorder inheritance pattern. Lgmd1 is inherited in an Autosomal dominant manner, meaning that only one copy of faulty gene is enough for disease to appear. Lgmd2, on the other hand, is inherited in anA Autosomal Recessive manner, meaning that both copies of causative Gene one inherited from each parent must carry Mutation for disease to develop.
Although there are some common themes recognizable in main types of LGMD, age at onset, severity, and progression of symptoms associated with LGMD may vary greatly from case to case, even among members of the same family. Some cases of LGMD may have onset during adulthood, mild symptoms, and slow progression; others may have onset during childhood and early severe disability such as difficulty climbing stairs and walking. Some individuals eventually require a wheelchair. In most cases, childhood onset of LGMD results in more severe disorder that progress more rapidly than adolescent or adult onset cases. Major symptoms of LGMD are progressive wasting and weakness of proximal muscles of hip and shoulder areas. Proximal muscles are muscles that are closest to the center of the body, such as muscles of the shoulder, pelvis, and upper arms and legs. Muscle weakness may spread from proximal muscles to affect distal muscles. Distal muscles are those farther from the center of the body and include muscles of lower arms and legs and hands and feet. Muscle weakness usually affects muscles of the pelvic and hip area first and affected individuals may have difficulty standing from a sitting position or walking up stairs. Weakness of hip and upper leg muscles may cause distinctive waddling gait. Eventually, muscle weakness affects muscles of the upper arms and shoulders. Consequently, affected individuals may have difficulty raising their arms over their heads or carrying heavy objects. Muscle weakness may be associated with soreness in muscles and joint pain. Additional abnormalities that may develop in individuals with LGMD include abnormal side - to - side curvature of spine, abnormal front - to - back curvature of spine, thickening and shortening of tissue that causes deformity and restricted movement of affected areas, especially joints, and overgrowth of certain muscles such as calf muscle. In some particular forms of LGMD, weakening of heart muscle, know as cardiomyopathy, can occur. Cardiomyopathy is a progressive condition that may result in impaired ability of the heart to pump blood; fatigue; heart block; irregular heartbeats and, potentially, heart failure. Heart abnormalities are not associated with all forms of LGMD. Muscles of the respiratory system may also become involved in some cases, resulting in difficulty swallowing, slur speech, and breathing difficulties. Breathing difficulties may become progressively worse in such cases. At least 17 different forms of autosomal recessive LGMD have been identify. These disorders are characterized by progressive weakness of muscles of the pelvic girdle, legs, arms and shoulders. Progression of muscle weakness may be slow or rapid and may vary even among individuals in the same family. Intelligence is normal. The age of onset varies from subgroup to subgroup. Overall, onset is more common in childhood but it may even occur late in adult life. This form of LGMD usually affects children between the ages of 8 - 15, but may range from 2 - 40 years of age.
Lgmd can develop at any age. In conditionsA early stages, patients may take on unusual walking gait, have difficulty running, fall more frequently and struggle with standing up after sitting on the floor. Muscle weakness typically first appears in shoulders, with shoulder blades sticking out to create a winging effect. Further muscle atrophy around the shoulder girdle prevents patients from being able to hold their arms extend or up in the air. Cardiomyopathy, or atrophy of heart muscle, affects some forms of LGMD. Patients are also at risk of developing weakened diaphragm muscles required for breathing. These more severe symptoms are associated with particular types of LGMD.
|LGMD2A||CAPN3 19||Most common type world-wide, accounts for 15-40% of all LGMD cases|
|LGMD2B||DYSF 20||The second most common type, accounts for 5-35% of LGMD cases 21|
|LGMD2G||TCAP 23 , 24|
|LGMD2J||TTN 26 , 27|
|LGMD2N||POMT2 31 , 32|
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