Duchenne Muscular Dystrophy

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Duchenne muscular dystrophy (DMD) is one of many types of muscular dystrophy. Muscular dystrophy is a genetic condition that is characterised by the degeneration of muscle tissue and increased susceptibility to damage, it progressively worsens throughout a sufferers life.<br>
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Duchenne muscular dystrophy (DMD) is the most common and severe type of muscular dystroph<ref>https://www.nichd.nih.gov/health/topics/musculardys/conditioninfo/pages/types.aspx</ref>. It is a genetic condition that is characterised by the degeneration of muscle tissue and increased susceptibility to damage, it progressively worsens throughout a sufferers life.  
  
Symptoms can be spotted from early infancy (anthing before&nbsp;6 years old), walking usually becomes difficult around the age of 12, and around the age of 20 problems with the heart and breathing will occur.<ref>https://www.nlm.nih.gov/medlineplus/ency/article/000705.htm</ref>
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=== Symptoms ===
  
=== Cause<u></u> ===
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Signs of DMD can be spotted from early infancy, usually between the age of 2 and 3, and weakness most often begins in the upper legs and pelvis. Sufferers are usually unable to walk by the age of 12, and around 20 problems with the heart and breathing start to occ<ref>https://www.nlm.nih.gov/medlineplus/ency/article/000705.htm</ref>.Symptoms would typically include:
  
DMD is caused by a mutation in the [[Dystrophin gene|dystrophin gene]], the largest known gene in the [[Human genome|human genome]], the mutation leads to a non-functional dystrophin protein being synthesised<ref name="Kay Davies">http://jp.physoc.org/site/misc/editorinterviews.xhtml#kdavies</ref>. Dystrophin is essential in muscles and without the protein, the [[Muscles|muscles]] will deteriorate and eventually resulting in death, usually in the first two to three decades of a sufferers life, this is due to the cardiac muscles, as well as those associated with breathing, eventually failing.<br>
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*Frequent falls
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*Difficulty getting up from a lying or sitting position
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*Trouble running and jumping
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*Waddling gait
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*Walking on the toes
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*Large calf muscles
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*Muscle pain and stiffness
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*Learning disabilities<ref>https://www.mayoclinic.org/diseases-conditions/muscular-dystrophy/basics/symptoms/con-20021240</ref>
  
It is X-linked recessive and so is only passed on if the mother is a carrier. This is also why sufferers will usually be boys because they only have one X chromosome, and so if that is mutated they do not have another to compensate.&nbsp;It is very rare that&nbsp;a girl will show problems but they can be a carrier. <ref>https://www.nlm.nih.gov/medlineplus/ency/article/000705.htm</ref>
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=== Cause ===
  
=== Treatment  ===
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DMD, in the majority of cases, is caused by deletion mutations<ref>https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3730798/</ref> in the [[Dystrophin gene|dystrophin gene]]. This is the largest known gene in the [[Human genome|human genome]], and it is known that the mutation leads to a non-functional dystrophin protein being synthesised<ref name="Kay Davies">http://jp.physoc.org/site/misc/editorinterviews.xhtml#kdavies</ref>.
  
There is currently no permanent cure for muscular dystrophy, there are, however a wide range of treatments designed to help minimise the effects of the disease and increase the patients quality of life.  
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Dystrophin is essential in muscles and without the protein, the [[Muscles|muscles]] will deteriorate. This is accompanied by an increase in amounts of fatty and connective tissue<ref>https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4651452/</ref>. This usually leads to death within the third or fourth decade of a sufferers life, due to how quickly muscle deterioration progresses. Death is caused by cardiac and respiratory muscles eventually failing.  
  
Some of these treatments are changes to lifestyle, for example, light exercises such as swimming can help to lessen the effects. There are also some drugs that can be used to treat the condition, such as steroids. Steroids can help to reduce the rate of muscle loss and are effective for six months to two years.7<ref name="NHS">http://www.nhs.uk/Conditions/Muscular-dystrophy/Pages/Treatment.aspx</ref> Beta blockers and ACE&nbsp;inhibitors can also be used to treat heart failure. There can also be surgery to correct things such as scoliosis. However, these things are&nbsp;not cures, they are just things to help.<ref>http://www.nhs.uk/conditions/muscular-dystrophy/Pages/Introduction.aspx</ref>
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It is an X-linked recessive mutation and so is only passed on if the mother is a carrier. This is also why sufferers will usually be boys because they only have one X chromosome, and so if that is mutated they do not have another to compensate. It is very rare that a girl will show problems, as they have two X chromosome and the chance of both X chromosomes carrying a mutation is extremely small, but they can be a carrie<ref>https://www.nlm.nih.gov/medlineplus/ency/article/000705.htm</ref>.
  
Creatine can also be taken to help lessen the effects of the condition, it helps to improve muscle stregnth while causing very few side effects.<ref name="NHS">http://www.nhs.uk/Conditions/Muscular-dystrophy/Pages/Treatment.aspx</ref><br>
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=== Treatment ===
  
=== The Future  ===
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There is currently no permanent cure for muscular dystrophy; however, a wide range of treatments have been designed to help minimise the effects of the disease and increase the patients quality of life.
  
More recently, genetic treatments are being developed to try and cure the disease entirely, this has not yet been successfull but it is hoped that with continued research the dystrpohin gene can be replaced in it's entirety for a functioning copy.<ref name="PubMed">http://www.ncbi.nlm.nih.gov/pubmed/18422374</ref><br>
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Some of these treatments are changes to lifestyle, for example, light exercises such as swimming can help to lessen the effects. There are also some drugs that can be used to treat the condition, such as steroids. Steroids can help to reduce the rate of muscle loss and are effective for six months to two years<ref name="NHS">http://www.nhs.uk/Conditions/Muscular-dystrophy/Pages/Treatment.aspx</ref>. Beta blockers and ACE inhibitors can also be used to treat heart failure. There can also be surgery to correct things such as scoliosis. However, these treatments cannot cure the disease, and can only aid in increasing the patients quality of life<ref>http://www.nhs.uk/conditions/muscular-dystrophy/Pages/Introduction.aspx</ref>.
  
=== References: ===
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Creatine can also be taken to help lessen the effects of the condition, it does this by helping to improve muscle strength while causing very few side effects<ref name="NHS">http://www.nhs.uk/Conditions/Muscular-dystrophy/Pages/Treatment.aspx</ref>.
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A recent study from October 2015, has yielded positive results into the possibility of long-term treatment of sufferers of DMD. Genetically removing of the P2X purinoceptor 7 protein in DMD mice has resulted in the reduction of several symptoms of DMD 'In dystrophic muscles at 4 wk there was an evident recovery in key functional and molecular parameters such as improved muscle structure (minimum Feret diameter, p &lt; 0.001), increased muscle strength in vitro (p &lt; 0.001) and in vivo (p = 0.012), and pro-fibrotic molecular signatures. Serum creatine kinase (CK) levels were lower (p = 0.025), and reduced cognitive impairment (p = 0.006) and bone structure alterations (p &lt; 0.001) were also apparent'<ref>http://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.1001888</ref>. The removal of the protein was made possible by mating mdx Mice (affected) with mice that do not have the gene that codes for P2RX7, resulting in offspring with a non-functioning form of the protein. Although no clinical trials have taken place, there is hope that the use of P2RX7 antagonists may be able to increase the quality of life for DMD sufferers in the future<ref>http://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.1001888</ref>.
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=== The Future ===
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More recently, genetic treatments are being developed to try and cure the disease entirely, this has not yet been successful but it is hoped that with continued research the dystrophin gene can be replaced in its entirety for a functioning copy<ref name="PubMed">http://www.ncbi.nlm.nih.gov/pubmed/18422374&amp;amp;lt;/ref&amp;amp;lt;ref&amp;amp;gt;Anthony Sinadinos et al, Oct 2015) DOI: 10.1371/journal.pmed.1001888/</ref>.
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=== References: ===
  
 
<references />
 
<references />

Latest revision as of 12:03, 5 December 2017

Duchenne muscular dystrophy (DMD) is the most common and severe type of muscular dystroph[1]. It is a genetic condition that is characterised by the degeneration of muscle tissue and increased susceptibility to damage, it progressively worsens throughout a sufferers life.

Contents

Symptoms

Signs of DMD can be spotted from early infancy, usually between the age of 2 and 3, and weakness most often begins in the upper legs and pelvis. Sufferers are usually unable to walk by the age of 12, and around 20 problems with the heart and breathing start to occ[2].Symptoms would typically include:

Cause

DMD, in the majority of cases, is caused by deletion mutations[4] in the dystrophin gene. This is the largest known gene in the human genome, and it is known that the mutation leads to a non-functional dystrophin protein being synthesised[5].

Dystrophin is essential in muscles and without the protein, the muscles will deteriorate. This is accompanied by an increase in amounts of fatty and connective tissue[6]. This usually leads to death within the third or fourth decade of a sufferers life, due to how quickly muscle deterioration progresses. Death is caused by cardiac and respiratory muscles eventually failing.

It is an X-linked recessive mutation and so is only passed on if the mother is a carrier. This is also why sufferers will usually be boys because they only have one X chromosome, and so if that is mutated they do not have another to compensate. It is very rare that a girl will show problems, as they have two X chromosome and the chance of both X chromosomes carrying a mutation is extremely small, but they can be a carrie[7].

Treatment

There is currently no permanent cure for muscular dystrophy; however, a wide range of treatments have been designed to help minimise the effects of the disease and increase the patients quality of life.

Some of these treatments are changes to lifestyle, for example, light exercises such as swimming can help to lessen the effects. There are also some drugs that can be used to treat the condition, such as steroids. Steroids can help to reduce the rate of muscle loss and are effective for six months to two years[8]. Beta blockers and ACE inhibitors can also be used to treat heart failure. There can also be surgery to correct things such as scoliosis. However, these treatments cannot cure the disease, and can only aid in increasing the patients quality of life[9].

Creatine can also be taken to help lessen the effects of the condition, it does this by helping to improve muscle strength while causing very few side effects[8].

A recent study from October 2015, has yielded positive results into the possibility of long-term treatment of sufferers of DMD. Genetically removing of the P2X purinoceptor 7 protein in DMD mice has resulted in the reduction of several symptoms of DMD 'In dystrophic muscles at 4 wk there was an evident recovery in key functional and molecular parameters such as improved muscle structure (minimum Feret diameter, p < 0.001), increased muscle strength in vitro (p < 0.001) and in vivo (p = 0.012), and pro-fibrotic molecular signatures. Serum creatine kinase (CK) levels were lower (p = 0.025), and reduced cognitive impairment (p = 0.006) and bone structure alterations (p < 0.001) were also apparent'[10]. The removal of the protein was made possible by mating mdx Mice (affected) with mice that do not have the gene that codes for P2RX7, resulting in offspring with a non-functioning form of the protein. Although no clinical trials have taken place, there is hope that the use of P2RX7 antagonists may be able to increase the quality of life for DMD sufferers in the future[11].

The Future

More recently, genetic treatments are being developed to try and cure the disease entirely, this has not yet been successful but it is hoped that with continued research the dystrophin gene can be replaced in its entirety for a functioning copy[12].

References:

  1. https://www.nichd.nih.gov/health/topics/musculardys/conditioninfo/pages/types.aspx
  2. https://www.nlm.nih.gov/medlineplus/ency/article/000705.htm
  3. https://www.mayoclinic.org/diseases-conditions/muscular-dystrophy/basics/symptoms/con-20021240
  4. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3730798/
  5. http://jp.physoc.org/site/misc/editorinterviews.xhtml#kdavies
  6. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4651452/
  7. https://www.nlm.nih.gov/medlineplus/ency/article/000705.htm
  8. 8.0 8.1 http://www.nhs.uk/Conditions/Muscular-dystrophy/Pages/Treatment.aspx
  9. http://www.nhs.uk/conditions/muscular-dystrophy/Pages/Introduction.aspx
  10. http://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.1001888
  11. http://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.1001888
  12. http://www.ncbi.nlm.nih.gov/pubmed/18422374&amp;lt;/ref&amp;lt;ref&amp;gt;Anthony Sinadinos et al, Oct 2015) DOI: 10.1371/journal.pmed.1001888/
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