Muscular dystrophy how does it affect the body

From one type of muscular dystrophy to another, there is variation in:. Duchenne muscular dystrophy DMD and Becker muscular dystrophy BMD are often discussed together because they cause similar patterns of weakness and are inherited in the same way. These conditions are caused by an alteration in the DMD gene. This gene is responsible for the production of a large protein dystrophin which provides a scaffold structure to muscle fibres. This protects them from damage during muscle contraction.

Without this protein the muscles gradually break down. DMD mostly affects boys, but girls can be affected too. Duchenne muscular dystrophy is not usually noticeable before the age of two or three. Symptoms and signs include:. The rate of muscle degeneration in people with Becker muscular dystrophy BMD varies greatly between individuals.

Signs and symptoms of the condition are similar to those of DMD, but are usually milder and more varied. Facioscapulohumeral dystrophy FSH is a form of muscular dystrophy that affects the face and shoulders. It is generally considered less serious than other forms of muscular dystrophy.

This condition gets its name from the areas of the body that are affected most often — the muscles:. Some muscle groups on one side of the body are stronger than those on the other side. Onset of FSH can occur in infants, but symptoms may appear at any time from childhood until someone is in their 50s. Typical facial features of FSH include:. In severe early-onset FSH, deafness is a common symptom. Changes also occur in the eyes, although this seldom affects vision.

However, people with FSH should have their eyes checked regularly. Other issues faced by people with FSH include:. Due to the understated and variable nature of FSH symptoms, health professionals are sometimes challenged to identify the condition. This is where genetic testing can quickly assist with a diagnosis. On average, FSH muscular dystrophy progresses slowly and the level of severity eventually seems to plateau level off. In very mild cases, it may not be possible to detect that the disease is progressing.

Myotonic dystrophy is the most common adult form of muscular dystrophy. It is also known as Steinert's disease and dystrophia myotonica. Unlike the other muscular dystrophies, the muscle weakness is accompanied by myotonia delayed relaxation of muscles after contraction and by various other non-muscular symptoms.

The first muscles to be affected by weakness are those of the face, neck, hands, forearms, and feet. Myotonic dystrophy can affect the tissues and organs of many body systems.

The effects can include:. Fifty per cent of people with myotonic dystrophy show visible signs by about twenty years of age. But a significant number do not develop clear-cut symptoms until after age fifty. When myotonic dystrophy is suspected because it is present in other members of the family , careful examination may reveal typical features before obvious symptoms appear.

Myotonic dystrophy is inherited in an autosomal dominant manner. This means that the condition can be caused by inheriting just one copy of the altered gene. We inherit one copy of each gene from our mother and father.

Therefore, when a person with myotonic dystrophy goes on to have children, there is a 50 per cent chance that each child will have myotonic dystrophy. The course of myotonic dystrophy varies widely, even in the same family. There are people with the condition whose symptoms are so mild they hardly know the condition is present. Whatever muscle weakness they experience is something they assume to be normal and adapt to.

In some cases, the only symptom may be a cataract. Respiratory infections may be treated with antibiotics. Physical therapy can help prevent deformities, improve movement, and keep muscles as flexible and strong as possible. Options include passive stretching, postural correction, and exercise.

A program is developed to meet the individual's needs. Therapy should begin as soon as possible following diagnosis, before there is joint or muscle tightness. Occupational therapy may help some people deal with progressive weakness and loss of mobility. Some individuals may need to learn new job skills or new ways to perform tasks while other persons may need to change jobs.

Assistive technology may include modifications to home and workplace settings and the use of motorized wheelchairs, wheelchair accessories, and adaptive utensils. Speech therapy may help individuals whose facial and throat muscles have weakened. Individuals can learn to use special communication devices, such as a computer with voice synthesizer.

Dietary changes have not been shown to slow the progression of MD. Proper nutrition is essential, however, for overall health. Limited mobility or inactivity resulting from muscle weakness can contribute to obesity, dehydration, and constipation. A high-fiber, high-protein, low-calorie diet combined with recommended fluid intake may help. Feeding techniques can help people with MD who have a swallowing disorder and find it difficult to pass from or liquid from the mouth to the stomach. The prognosis varies according to the type of MD and the speed of progression.

Some types are mild and progress very slowly, allowing normal life expectancy, while others are more severe and result in functional disability and loss of ambulation. The goals of these studies are to increase understanding of MD and its causes, develop better therapies, and, ultimately, find ways to treat it.

Advances in basic research are essential to the basic understanding of each type of MD. While many genes that cause muscular dystrophy still remain to be identified, advances in gene sequencing has aided the identification of genes that may be involved for 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 the 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 the NIH and other agencies, as well as the venture philanthropy programs supported by patient advocacy groups, have attracted biotechnology and pharmaceutical firm investments into therapies for the MDs.

Currently, a variety of strategies are employed in developing new drug and biologic therapies for the range of MDs. Strategies being explored are either specific to a particular type of MD or may address disease progression that may apply to multiple types of MD. Gene replacement therapy Gene therapy has the potential for directly addressing the primary cause of MD by providing for the production of the missing protein. Hurdles to be overcome include determining the timing of the therapy to possibly overcome the genetic defect , avoiding or easing potential immune responses to the replacement gene, and, in the case of Duchenne MD, the large size of the gene to be replaced.

For those MDs with central nervous system consequences congenital muscular dystrophy and myotonic dystrophy , researchers are developing and fine-tuning gene therapy vectors a way to deliver genetic materials to cells that can cross the protective blood-brain barrier.

Recent progress in delivery of replacement genes in MD includes considerable refinement of the viral vector types that improve the targeting to skeletal muscle and vascular approaches to deliver replacement gene 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. The strategies for assessing potential immune responses to the 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 the disease causing mutations, through newborn screening, may be necessary for gene replacement therapy to be used early enough to mitigate progression of the disease. Clinical testing of gene therapy strategies in MD has been underway for Duchenne and limb girdle muscular dystrophy. Injections of gene therapy vectors into single muscles of participants were done as a first step to establish safety of the approach.

With the support of extensive studies in animal models, clinical trials are now moving toward testing of gene therapy of all muscles of entire limbs, using an isolated vascular delivery approach. If isolated limb delivery approaches prove safe and effective, research will move to systemic delivery of gene therapy vectors so all muscles can be treated simultaneously.

Utrophin is a protein that is closely related to dystrophin and is not affected in the gene mutations that cause Duchenne MD. Targeting increased expression of utrophin may prove a useful approach in treating Duchenne MD. NIH supports both gene therapy and small molecule drug development programs to increase the muscle production of utrophin.

Finally, modifier genes—genes with activities that act to reduce the severity of MD—have been discovered by NIH-funded teams.

These genes, including latent TGF binding protein 4 and osteopontin, represent new therapeutic targets to potentially reduce the severity of several types of muscular dystrophy. Genetic modification therapy to bypass inherited mutations Most individuals with Duchenne have mutations in the dystrophin gene that cause it to function improperly and stop producing the dystrophin protein.

Two strategies are currently under study to bypass dystrophin mutations, one of which is drugs that cause the protein synthesis machinery to ignore the premature stop signal and produce functional dystrophin. This strategy, which is potentially useful in about 15 percent of individuals with Duchenne MD, is currently in clinical trials. Second, a more recent approach uses antisense oligonucleotides short strands of nucleic acid designed to block the transfer of some genetic information into protein production to alter splicing and produce nearly a full-length dystrophin gene, potentially converting an individual with Duchenne to a much milder Becker MD.

Two biotechnology companies are currently testing oligonucleotide drugs in advanced clinical trials for people who require skipping of exon 51 of dystrophin. An exon is a coding sequence in a gene for a protein. Antisense oligonucleotide technology is also being evaluated for use in myotonic dystrophy, but by a different mechanism than in Duchenne MD. In myotonic dystrophy, long duplications of repetitive DNA sequences lead to production of a toxic RNA that sequesters a splicing regulator, Muscleblind, causing mis-splicing of many genes in muscle and brain.

This approach, in partnership with academic investigators and biotechnology and pharmaceutical companies, has the potential to address all people having myotonic dystrophy and is planned to be in clinical trials within the next few years. Drug-based therapy to delay muscle wasting by promoting muscle growth or mitigating damage due to inflammation Progressive loss of muscle mass is primarily responsible for reduced quality and length of life in MD. Drug treatment strategies designed to slow this muscle degeneration can have substantial impact on quality of life.

Similarly, skeletal muscle has the ability to repair itself, but its regeneration and repair mechanisms are progressively depleted during the course of several types of MD. Understanding the repair mechanisms may provide new therapies to slow, and possibly stabilize, muscle degeneration.

Corticosteroids are known to extend the ability of people with Duchenne MD to walk by up to 2 years, but steroids have substantial side effects and their mechanism of action is unknown. Since several corticosteroid protocols are used, an NINDS-funded study is evaluating drugs and their efficacy and tolerability at different doses in order to determine optimal clinical practice for their use in Duchenne MD.

Preclinical drug development efforts supported by NINDS and NIAMS are developing a peptide therapeutic that has, in animal models, dual activity in mitigating muscle damage due to inflammation and also enhancing muscle regeneration. Efforts to preserve muscle mass through inhibition of a negative regulator of muscle growth, myostatin, have encountered some roadblocks, including failed clinical trials, but are still under study.

Cell-based therapy The muscle cells of people with MD often lack a critical protein, such as dystrophin in Duchenne MD or sarcoglycan in some of the limb-girdle MDs. Scientists are exploring the possibility that the missing protein can be replaced by introducing muscle stem cells capable of making the missing protein in new muscle cells.

Such new cells would be protected from the progressive degeneration characteristic of MD and potentially restore muscle function in affected persons.

The natural regenerative capacity of muscle provides possibilities for treatment of MD. Researchers have shown that stem cells can be used to deliver a functional dystrophin gene to skeletal muscles of dystrophic mice and dogs. The focus of research has been on identifying the cell types with the highest potential for engraftment and growth of muscle and on strategies to deliver these muscle precursor cells to human skeletal muscles. Overall, cell-based therapeutic approaches are under consideration for multiple types of MD.

With the dramatic advances in understanding disease mechanisms, significant therapy development efforts are now being launched in many types of MD. NINDS funding supports teams working on the disease mechanisms in facioscapulohumeral muscular dystrophy, central nervous system involvement in myotonic dystrophy, and on the role of fibrosis in Duchenne MD.

Similarly, NIAMS-supported projects are identifying novel therapy development targets that are attracting interest from biotechnology and pharmaceutical companies and will help move toward therapy development programs for all types of MD.

Importantly, parallel efforts need to be made in clinical trial readiness, so that clinical trials are feasible when a candidate therapeutic reaches that stage. Patient registries, natural history studies, biomarker identification, development of clinical trial endpoint measures, and emergence of standards of care are all essential in supporting clinical trials and are being advanced in several types of muscular dystrophy with the support of both public and private sector partners.

The NIH has recently undertaken several new initiatives in training, career development, and research that are targeted toward MD. These advances, along with the NINDS focus on translational and clinical research, will lead to the growth of clinical trials and promising treatment strategies.

The MD Coordinating Committee is made up of physicians, scientists, NIH professional staff, and representatives of other federal agencies and voluntary health organizations with a focus on MD. The purpose of the group is to help NIH add new capabilities to the national effort to understand and treat MD, without duplicating existing programs.

The MD Coordinating Committee has developed a broad Action Plan for the Muscular Dystrophies and continues to refine the plan to improve basic, translational, and clinical research in MD, with the goal of improving the quality of life for people with MD. The NIH is expanding and intensifying its research efforts on the muscular dystrophies and has established the Senator Paul D. Wellstone Muscular Dystrophy Cooperative Research Centers of Excellence to promote basic and clinical research on these disorders.

The Act also authorized the Centers for Disease Control and Prevention to award grants for epidemiologic studies, data collection, and development of standards of care for several types of MD. Other federal agencies contribute to this research initiative. Research has led to the discovery of disease mechanisms and improved treatment for many forms of MD. Current research promises to generate further improvements. In the coming years, physicians and affected individuals can look forward to new forms of therapy developed through an understanding of the unique traits of MD.

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Facebook Twitter LinkedIn Syndicate. What is Muscular Dystrophy? Minus Related Pages. About 14 in , males 5 — 24 years of age Who is more likely to be affected: males or females? Males When does muscle weakness typically begin? Upper legs and upper arms What other parts of the body can be affected? Myotonic DM. About 8 in , people of all ages are affected Who is more likely to be affected: males or females?

Males and females equally When does muscle weakness typically begin? Face, neck, arms, hands, hips, and lower legs What other parts of the body can be affected? Heart, lungs, stomach, intestines, brain, eyes, and hormone-producing organs Learn how myotonic dystrophy is inherited external icon.

About 2 in , people of all ages Who is more likely to be affected: males or females? Upper arms, upper legs What other parts of the body can be affected? Heart, spine, hips, calves, and trunk Learn how limb-girdle muscular dystrophy is inherited external icon. Facioscapulohumeral FSHD. About 4 in , people of all ages Who is more likely to be affected: males or females? Young adulthood Which parts of the body show weakness first?

Face, shoulders, and upper arms What other parts of the body can be affected? Eyes, ears, and lower legs Learn how facioscapulohumeral dystrophy is inherited external icon. Congenital CMD. About 1 in , people of all ages Who is more likely to be affected: males or females? At birth or in early infancy Which parts of the body show weakness first? Neck, upper arms, upper legs, and lungs What other parts of the body can be affected?

Brain, heart, and spine Learn how congenital muscular dystrophy is inherited external icon. Support groups and organisations may help you understand and come to terms with your condition. They can also provide useful advice and support for those who care for people with MD. Ask your GP or other healthcare professionals treating you about local support groups.

You can opt out of the register at any time. Page last reviewed: 20 July Next review due: 20 July What causes muscular dystrophy? Types of muscular dystrophy There are many different types of MD, each with somewhat different symptoms. Who's affected by muscular dystrophy? In the UK, around 70, people have MD or a related condition. Diagnosing muscular dystrophy Many different methods can be used to diagnose the various types of MD.