What is Duchenne Muscular Dystrophy?

Answer 1

Duchenne muscular dystrophy (DMD) is a severe recessive X-linked form of muscular dystrophy characterized by rapid progression of muscle degeneration, eventually leading to loss of ambulation and death. This affliction affects one in 3500 males, making it the most prevalent of muscular dystrophies.

A:A very simple explanation of Duchenne Muscular Dystrophy (DMD)

Duchenne Muscular Dystrophy is an X chromosome-linked, inherited, progressive, muscle wasting disease, which affects approximately one out of 3,500 male children.

For explaining the nature of Duchenne Muscular Dystrophy (DMD), we might start with the chromosomes.

Chromosomes are specifically folded DNA molecules. We speak of chromosomes rather than DNA, because in this form the DNA molecules are visible under the microscope, therefore, distinguishable from each other.

In normal circumstances we have 46 nuclear chromosomes. In certain conditions, such as cancer (for example in cancerous 'HeLa cells'), the number of chromosomes could be different. The 46 chromosomes include 2 sex chromosomes as well. We inherit 23 nuclear chromosomes (22 plus 1 sex chromosome) from each of our parent.

Females have two X chromosomes (XX), males have one X and one Y (XY). They each contribute one to their child. Since the mother has two X-es, she passes down one X, therefore the father's chromosomes decides the child's sex.

Duchenne muscular dystrophy arises from the mother's defective sex chromosome. The disease is a recessive trait, meaning only one of the mothers' two XX sex chromosomes is defective and the other X chromosome is able to compensate.

For this reason, if she passes the disease-carrying chromosome to her daughter, the daughter's disease-free paternal X chromosome would compensate. The girl will carry, and potentially be able to pass, the faulty chromosome to her child/children, but, she, herself, will not be at all, or just mildly, affected.

If, however, her son gets the disease-carrying chromosome, he will not have that opportunity; due to his Y chromosome from his father, he cannot compensate. Unfortunately, he will get the full-blown disease.

While the majority of the disease are inherited from the mother, as detailed above, 'spontaneous mutations', when the damage to the gene happens in the male child, is also possible.

So, what is the role of the X chromosome in that disease?

The long DNA molecules, therefore their tightly packed forms, the chromosomes, have specific areas, called 'genes'. Every chromosome has its 'own' specific genes on their 'own' specific areas. Those genes have the 'blueprints', the instructions, for the body to build proteins. Proteins are compounds, specific substances, which are essential to life; they are vital for every function, feature, and aspects of the body.

If a gene is faulty, inherited from either or both parents, (Duchenne muscular dystrophy is inherited only from the mother), or damaged/changed by environmental factors (like radiation, chemicals, or others), also by life style (smoking for example), then it cannot provide a correct instruction to assemble a properly working protein.

The fault arise from mistakes in the instruction; some parts are missing, others are repeated, and some are changed. It is like someone is building a cupboard. If the instruction gives the wrong dimensions for some parts or even omit some others parts, then it would be impossible to build a proper cupboard.

Neither can the body assemble the protein, called 'dystrophin', from the improper instruction given by the defective Dystrophin gene of the X-chromosome.

Dystrophin is a muscle protein with mechanical and protective functions. It might involve in cell to cell communications, as well. Due to the lack of dystrophin protein the muscles became weaker, damage easily, and gradually break down, waste away.

Symptoms (difficulty in sitting unaided, delayed start for walking, frequent stumbling and falling, difficulty in getting up, for example), could start to appear as early as one year of age, and the disease quickly progresses to the stage when the child needs a wheelchair (around 8-12 years of age).

Since the disease weakens not only the skeletal muscles, but all muscles, heart rhythm and the pumping ability of the heart are also affected. Likewise, breathing becomes difficult and needs assistance as the disease progresses to those involved muscles.

Lifespan, unfortunately, is not expected to extend beyond 30 years. Cure is not possible at the present.

Treatments are aimed to delay the wastage, steroid medication (with Vitamin D and calcium supplement to counteract its possible bone weakening side-effect), physiotherapy, and water exercises, possibility of low frequency electrical muscle stimulation, among others.

Improving the quality of the patients' life includes corrective bone surgery (bone deformities occurs frequently) to improve posture and comfort, braces, use of wheelchair (manual then electric), heart medications/treatments, assistance with breathing (ventilator, masks, others), - education/information/help to parents and carers, for example.

Research is ongoing, internationally, on several possible aspects; a few examples are:

· 'Gene bandage', specifically designed for the protein assembling process to 'skip over' the faulty segment of the gene, enabling the production of dystrophin,

· Implantation of stem cells,

· 'utrophin-based therapy', Utrophin is another muscle protein with similar function. Research going on to use it for compensate for the lack of dystrophin,

· Researching a drug (recently trialled in Diabetes Type 2 research, as well), which, also, could increase the level of HSP72 (a specific protein). HSP72 expected to improve muscle function, decrease muscle break down, and increase lifespan by 20 %,

· and an older research into low frequency electrical muscle stimulation.

Answer 2

Boys affected by Duchenne muscular dystrophy can begin showing signs of weakness in their limbs, particularly in the legs and pelvis. This weakness can manifest itself in the following ways:

-difficulty running, jumping or climbing stairs.

-frequent falls.

-Increased difficulty walking

-loss of ambulation (ability to walk) by age 10-12

Additionally, there are several physical signs of Duchenne muscular dystrophy including:

-Enlarged calves(pseudohypertrophy)

-Walking on toes, often as a "waddle"

-Walking "chest out"

Answer 3

Some common phenotypes of DMD are: abnormally large calves and skeletal deformities including winged shoulder blades, scoliosis and bunions, all other visible attributes to the disease are caused by muscle wasting.

Answer 4

A very simple explanation of Duchenne Muscular Dystrophy (DMD)

Duchenne Muscular Dystrophy is an X chromosome-linked, inherited, progressive, muscle wasting disease, which affects approximately one out of 3,500 male children.

For explaining the nature of Duchenne Muscular Dystrophy (DMD), we might start with the chromosomes.

Chromosomes are specifically folded DNA molecules. We speak of chromosomes rather than DNA, because in this form the DNA molecules are visible under the microscope, therefore, distinguishable from each other.

In normal circumstances we have 46 nuclear chromosomes. In certain conditions, such as cancer (for example in cancerous 'HeLa cells'), the number of chromosomes could be different. The 46 chromosomes include 2 sex chromosomes as well. We inherit 23 nuclear chromosomes (22 plus 1 sex chromosome) from each of our parent.

Females have two X chromosomes (XX), males have one X and one Y (XY). They each contribute one to their child. Since the mother has two X-es, she passes down one X, therefore the father's chromosomes decides the child's sex.

Duchenne muscular dystrophy arises from the mother's defective sex chromosome. The disease is a recessive trait, meaning only one of the mothers' two XX sex chromosomes is defective and the other X chromosome is able to compensate.

For this reason, if she passes the disease-carrying chromosome to her daughter, the daughter's disease-free paternal X chromosome would compensate. The girl will carry, and potentially be able to pass, the faulty chromosome to her child/children, but, she, herself, will not be at all, or just mildly, affected.

If, however, her son gets the disease-carrying chromosome, he will not have that opportunity; due to his Y chromosome from his father, he cannot compensate. Unfortunately, he will get the full-blown disease.

While the majority of the disease are inherited from the mother, as detailed above, 'spontaneous mutations', when the damage to the gene happens in the male child, is also possible.

So, what is the role of the X chromosome in that disease?

The long DNA molecules, therefore their tightly packed forms, the chromosomes, have specific areas, called 'genes'. Every chromosome has its 'own' specific genes on their 'own' specific areas. Those genes have the 'blueprints', the instructions, for the body to build proteins. Proteins are compounds, specific substances, which are essential to life; they are vital for every function, feature, and aspects of the body.

If a gene is faulty, inherited from either or both parents, (Duchenne muscular dystrophy is inherited only from the mother), or damaged/changed by environmental factors (like radiation, chemicals, or others), also by life style (smoking for example), then it cannot provide a correct instruction to assemble a properly working protein.

The fault arise from mistakes in the instruction; some parts are missing, others are repeated, and some are changed. It is like someone is building a cupboard. If the instruction gives the wrong dimensions for some parts or even omit some others parts, then it would be impossible to build a proper cupboard.

Neither can the body assemble the protein, called 'dystrophin', from the improper instruction given by the defective Dystrophin gene of the X-chromosome.

Dystrophin is a muscle protein with mechanical and protective functions. It might involve in cell to cell communications, as well. Due to the lack of dystrophin protein the muscles became weaker, damage easily, and gradually break down, waste away.

Symptoms (difficulty in sitting unaided, delayed start for walking, frequent stumbling and falling, difficulty in getting up, for example), could start to appear as early as one year of age, and the disease quickly progresses to the stage when the child needs a wheelchair (around 8-12 years of age).

Since the disease weakens not only the skeletal muscles, but all muscles, heart rhythm and the pumping ability of the heart are also affected. Likewise, breathing becomes difficult and needs assistance as the disease progresses to those involved muscles.

Lifespan, unfortunately, is not expected to extend beyond 30 years. Cure is not possible at the present.

Treatments are aimed to delay the wastage, (steroid medication (with Vitamin D and calcium supplement to counteract its possible bone weakening side-effect), physiotherapy, and water exercises, possibility of low frequency electrical muscle stimulation, among others.

Improving the quality of the patients' life includes corrective bone surgery (bone deformities occurs frequently) to improve posture and comfort, braces, use of wheelchair (manual then electric), heart medications/treatments, assistance with breathing (ventilator, masks, others), - education/information/help to parents and carers, for example.

Research is ongoing, internationally, on several possible aspects; a few examples are:

· 'Gene bandage', specifically designed for the protein assembling process to 'skip over' the faulty segment of the gene, enabling the production of dystrophin,

· Implantation of stem cells,

· 'utrophin-based therapy', Utrophin is another muscle protein with similar function. Research going on to use it for compensate for the lack of dystrophin,

· Researching a drug (recently trialled in Diabetes Type 2 research, as well), which, also, could increase the level of HSP72 (a specific protein). HSP72 expected to improve muscle function, decrease muscle break down, and increase lifespan by 20 %,

· and an older research into low frequency electrical muscle stimulation.

Answer 5

The Duchenne Muscular Dystrophy is a genetic disorder where muscle fibres do not have a structural protein associated with the muscle cell membrane. The muscle fibres hence cannot function properly and undergo atrophy. Symptoms include thin and weak thighs, a poor sense of balance, clumsy walking, and difficulty in standing up.

Answer 6

Ever