Muscular Dystrophy Causes And Risk Factors
Muscular dystrophy is caused by defects in certain genes, with type determined by the abnormal gene. In 1986, researchers discovered the gene that, when defective or flawed, causes Duchenne muscular dystrophy. In 1987, the muscle protein associated with this gene was named dystrophin. Duchenne muscular dystrophy occurs when that gene fails to make dystrophin. Becker muscular dystrophy occurs when a different mutation in the same gene results in some dystrophin, but it’s either not enough or it’s poor in quality. Scientists have discovered and continue to search for the genetic defects that cause other forms of muscular dystrophy.
Most of the muscular dystrophies are a form of inherited disease called X-linked disorders or genetic diseases that mothers can transmit to their sons even though the mothers themselves are unaffected by the disease.
Men carry one X chromosome and one Y chromosome. Females carry two X chromosomes. Thus, in order for a girl to become affected by muscular dystrophy, both their X chromosomes would have to carry the defective gene — an extremely rare occurrence, since their mother would have to be a carrier and their father would have to have muscular dystrophy .
A female who carries the defective X chromosome can pass the disease to their son .
A few muscular dystrophies aren’t inherited at all and occur because of a new gene abnormality or mutation.
Hippocampal Dysfunction In Mdx Mice
The neurobehavioral profile of mdx mice is characterized by deficits in cognitive function , behaviors that are linked to dysregulation of hippocampal and amygdalar function. For example, the mdx mouse exhibits deficits in its capacity to learn and store spatial memories relative to controls . It also displays deficiencies in associative learning as well as in general processes of memory consolidation that are dependent on both the hippocampus and the amygdala . Changes in long- and short-term memory formation and consolidation have been associated with altered synapse morphology and plasticity linked to a loss of Dp427 . Interestingly, other in vivo and in vitro hippocampal-dependent functions, such as spatial learning, CA1 NMDA-dependent long-term potentiation , and its converse, long-term depression , have been found to be either intact or actually enhanced relative to controls .
Genetic Testing For Muscular Dystrophy
If muscular dystrophy runs in your family, a genetic counsellor can explain what genetic testing options are available to you and other family members. You may choose to visit a genetic counsellor if you are planning a family to find out your risk of passing the condition on to your child, or to arrange for prenatal tests. Read more about genetic testing for muscular dystrophy.
is connected with a wide range of support groups throughout Victoria and Australia and can connect you with other individuals and families affected by muscular dystrophy.
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What You Need To Know
- Duchenne muscular dystrophy, or DMD, is associated with the most severe clinical symptoms of all the muscular dystrophies.
- It is caused by a genetic mutation on one of the mothers X chromosomes, and researchers have identified some of the affected genes.
- Duchenne muscular dystrophy is caused by a genetic problem in producing dystrophin, a protein that protects muscle fibers from breaking down when exposed to enzymes.
- Duchenne muscular dystrophy mostly affects boys and occurs in one in 3,500 to 5,000 newborns. There is no higher risk for any ethnic group.
- Children affected by DMD may have some degree of cognitive problems, yet some have average or even higher-than-average intelligence.
Muscular dystrophy is a genetic problem that causes muscles to weaken and atrophy .
Muscle weakness may affect the skeletal muscle or the heart muscle. It is caused by the inability of muscles to respond to nerve impulses from the brain
Other Less Known Types Of Cmds Belonging To Alpha
Congenital muscular dystrophy type 1C
This subtype of CMD was first reported by Brockington et al. , who identified a new member of the fukutin family of proteins, FKRP, with the gene mapping to chromosome 19q13.3. The disorder manifests in the first few weeks of life with CMD and marked increase of serum CK. Several patients present with normal intelligence and normal brain structures on brain imaging. In the young adult age, the patients show heart involvement, severe weakness, and wasting of the shoulder girdle muscles hypertrophy and weakness of the leg muscles with calf and thigh hypertrophy and severe respiratory failure are also recorded. The MDC1C follows the nomenclature previously established for the MDC1A related to CMD with a primary laminin apha 2 deficiency and for MDC1B related to a secondary laminin alpha2 deficiency and calf hypertrophy linked to 1q42. The group MDC1C also includes clinical features of CMD/LGMD involving different genes , which manifests with early onset weakness and early onset LGMD without brain involvement and cardiomyopathy.
CMD with partial merosin deficiency
This form manifests with variable deficiency of the glycosylated aDG epitope and secondary laminin alpha 2 deficiency. The muscle involvement manifests with proximal limb girdle weakness, muscle hypertrophy, particularly in the calf, and early respiratory failure .
LARGE related CMD
Neonatal hypotonia: a challenge to reach the diagnosis
History and clinical examination
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Relation Of White Matter Integrity And Age Disease Duration And Ctg Repeat Size
Altogether, our data suggest that white matter affection is progressive over time in myotonic dystrophies. Despite this tempting speculation, cross-sectional data and correlation analyses, as obtained in our study, do not sufficiently allow analyses of the age- and disease duration-related impact on brain morphology in myotonic dystrophy types 1 and 2. Longitudinal MRI studies investigating the progress of grey and white matter changes over time and its role in clinical deterioration in both types of myotonic dystrophies are strongly required to address these issues appropriately in the future.
Fsh Muscular Dystrophy Difficulties
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:
- trouble combing hair, hanging out washing and reaching high shelves, due to an inability to raise the arms
- a tendency to trip due to foot drop
- a tendency for one or both knees to give out
- difficulty with stairs and steps.
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.
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What Research Is Being Done
The National Institute of Neurological Disorders and Stroke , a 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. The NINDS and its sister institutes, the National Institute of Arthritis and Musculoskeletal and Skin Diseases , the National Institute of Child Health and Human Development , and the National Heart, Blood, and Lung Institute , lead the MD research efforts conducted at the NIH and at grantee institutions throughout the country.
The NIH supports a broad range of basic, translational, and clinical research in the MDs. 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.
Muscular Dystrophy Signs And Symptoms
Muscle weakness is the primary sign of muscular dystrophy, and its progression can affect a persons ability to move, walk, and breathe. Symptoms can start at different ages and vary in severity and how fast they progress.
In the case of DMD, symptoms generally start between ages 3 and 5. Muscle weakness typically begins in the upper arms and upper legs and can spread to the heart, lungs, throat, stomach, intestines, and spine. DMDs rapid progression of muscle weakness means patients are often unable to walk by age 12 and can eventually require a respirator to breathe.
The progression of the disease can vary depending on the type of muscular dystrophy. Some forms cause a rapid progression of muscle weakness, while others result in a slower progression over a normal lifespan. Symptoms also vary from mild to severe, including losing the ability to walk.
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Effects Of 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. Nevertheless, these people do have myotonic dystrophy and can transmit a more severe version of the condition to their children.In most cases, weakness and muscle wasting starts with certain muscles and slowly progresses to the point of some physical inability. As it progresses it moves beyond the muscles originally involved to those of the shoulders, hips, and thighs. This muscle weakness rarely becomes severe until fifteen to twenty years after the onset of symptoms. The older a person is when muscle weakness is first noticed, the slower it progresses and the less serious the condition and effects.
How Are The Muscular Dystrophies Diagnosed
Both the individual’s medical history and a complete family history should be thoroughly reviewed to determine if the muscle disease is secondary to a 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 the person’s functional status or rule out many acquired muscle diseases. Thorough clinical and neurological exams can rule out disorders of the 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:
Genetic counseling can help parents who have a family history of MD determine if they are carrying one of the mutated genes that cause the disorder. Two tests can be used to help expectant parents find out if their child is affected.
Immunofluorescence testing can detect specific proteins such as dystrophin within muscle fibers. Following biopsy, fluorescent markers are used to stain the sample that has the protein of interest.
Neurophysiology studies can identify physical and/or chemical changes in the nervous system.
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Autosomal Dominant Inherited Disorder
A person inherits a gene difference from just one parent, on one of the 22 autosomal chromosomes.
Each child has a 50 percent chance of inheriting muscular dystrophy and people of all sexes are equally at risk. Because this is a dominant gene, only one parent needs to be a carrier for their child to develop muscular dystrophy.
Qol Of Patients With Muscular Dystrophy
Muscular dystrophy has an early onset, and thereafter body functions decrease progressively beginning with a decrease in motor functions that require the use of a wheelchair to maintain mobility and a decrease in the breathing function that require a ventilator to maintain breathing, which makes the patients bedridden. As a result, the patients behavior repertoire becomes severely restricted, and they require considerable assistance. Netterlund et al. investigated activities of daily living and the QOL of 45 people with muscular dystrophy and reported that all the sampled patients were living at home. The QOL was assessed by the Sickness Impact Scale and the Psychosocial Well-Being Questionnaire, which indicated that their disability and dependence on others increased, whereas ADL decreased during the previous 5 years. Moreover, the patients QOL and life satisfaction also decreased. Bostr ö m and Ahlstr ö m investigated 46 people with muscular dystrophy through interviews using a qualitative research approach for 10 years . They reported that nearly all muscular dystrophy patients had decreasing functions such as limited mobility, increasing fatigue, and feebleness, accompanied by psychological distress. Moreover, if there is a difficulty in securing assistance for patients to continue living in their homes, they must live in recuperation wards.
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Psychopathological Features And Personality Of Dm1 Patients
Some studies pointed that depression and fatigue predict psychological and physical QOL in patients with muscular diseases . Additionally, apathy could promote social inhibition and avoidance of social interactions . All of them, in conjunction with each other, lead to the deterioration of the QOL. Therefore, the psychological interventions for DM1 should incorporate these factors as potential targets for improving patients QOL.
Minier et al. conducted a systematic literature review of psychopathological features in DM1 and reported that patients with DM1 present mild psychopathological problems, such as interpersonal difficulties, lack of interest, dysphoria, concern about bodily functioning, and hypersensibility. However, they do not present more psychiatric disorders than the general population, except for personality disorders and depression. Moreover, avoidant personality disorder was the most common of several personality disorders among DM1 patients.
Genetic Counselling For Muscular Dystrophy
If your child or another family member has been diagnosed with muscular dystrophy, or if it runs in your family, it may be helpful to speak to a genetic counsellor.
Genetic counsellors are health professionals qualified in both counselling and genetics. As well as providing emotional support, they can help you to understand muscular dystrophy and what causes it, how it is inherited, and what a diagnosis means for your child’s health and development, and for your family.
Genetic counsellors are trained to provide information and support that is sensitive to your family circumstances, culture and beliefs.
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How Is Muscular Dystrophy Detected
The first DMD symptoms often begin to appear around age 2 or 3, but some signs may be present earlier. However, the earliest signs may be difficult to spot, and the average age of diagnosis of DMD is 4.
Be alert for the developmental warning signs of DMD in your child. Signs include:
- Difficulty standing from a sitting or lying position
- Delayed walking
- Weakness or stiffness in the neck
- Walking with a waddling, toe-walking, or legs-apart gait
- Difficulty running or jumping
- Speech delays
In other types of MD, symptoms may surface later. Causes for concern include progressive muscle weakness, frequent falls, or muscle stiffness.
Does Muscular Dystrophy Affect The Brain
Due to the lack of dystrophin protein in brain, which provides stretching to the muscles, muscular dystrophy has an impact on the brain and it affects it. The effect of muscular dystrophy is more prominently seen on the congenital muscular dystrophy rather than the acquired form.1 Following are the effects of muscular dystrophy on brain:
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Diagnosis Of Muscular Dystrophy
Diagnosis before the age of two or three is possible through:
- a blood test to check the levels of a protein called creatine phosphokinase . CPK is produced by damaged muscle, so levels are very high in people with muscular dystrophy
- genetic testing if it is known that a condition runs in a family, a test to detect the genetic change can be performed on the DNA in the blood
- a muscle biopsy removal of a small piece of muscle tissue for examination under a microscope
- electromyography checks the health of the muscles and the nerves that control the muscles. It involves inserting a very thin needle into the muscle.
Early diagnosis of muscular dystrophy will enable the most appropriate management of the condition from a young age.
Symptoms Of Muscular Dystrophy
Following are the symptoms of muscular dystrophy:
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