Down's syndrome

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Down's syndome is disorder caused by having an extra [[Chromosome|chromosome]] on chromosome 21 (referred to as [[Trisomy 21|trisomy 21]]), giving a total of 47 chromosomes instead of the normal 46 in humans.&nbsp;<span style="font-size: 13.28px; line-height: 19.92px;">Most cases of Down's syndrome are a result of a random chromosomal defect during the formation of reproductive cells, especially egg cells. An error during [[Gamete|gamete]] cell division, [[Nondisjunction|non-disjunction]], results in the cell with an abnormal number of chromosomes.&nbsp;</span><span style="line-height: 1.5em; font-size: 13.28px;">This extra chromosome copy disrupts the normal course of&nbsp;[[Brain|brain]] and body development, thus affecting both physical development and intellectual ability. Although individuals with Down's syndrome behave and look similar, their intellectual capability varies from mild to moderately low. As sufferers age (often about the age of 50), they may often experience a progressive decline in cognitive function, which can result in an increased risk of </span>[[Alzheimer's|Alzheimer's]]<span style="line-height: 1.5em; font-size: 13.28px;">, a [[Neurodegeneration|neurodegenerative]] disease that causes </span>[[Dementia|dementia]]<span style="line-height: 1.5em; font-size: 13.28px;">: a gradual loss of memory, motor skills, and judgement.&nbsp;</span>  
 
Down's syndome is disorder caused by having an extra [[Chromosome|chromosome]] on chromosome 21 (referred to as [[Trisomy 21|trisomy 21]]), giving a total of 47 chromosomes instead of the normal 46 in humans.&nbsp;<span style="font-size: 13.28px; line-height: 19.92px;">Most cases of Down's syndrome are a result of a random chromosomal defect during the formation of reproductive cells, especially egg cells. An error during [[Gamete|gamete]] cell division, [[Nondisjunction|non-disjunction]], results in the cell with an abnormal number of chromosomes.&nbsp;</span><span style="line-height: 1.5em; font-size: 13.28px;">This extra chromosome copy disrupts the normal course of&nbsp;[[Brain|brain]] and body development, thus affecting both physical development and intellectual ability. Although individuals with Down's syndrome behave and look similar, their intellectual capability varies from mild to moderately low. As sufferers age (often about the age of 50), they may often experience a progressive decline in cognitive function, which can result in an increased risk of </span>[[Alzheimer's|Alzheimer's]]<span style="line-height: 1.5em; font-size: 13.28px;">, a [[Neurodegeneration|neurodegenerative]] disease that causes </span>[[Dementia|dementia]]<span style="line-height: 1.5em; font-size: 13.28px;">: a gradual loss of memory, motor skills, and judgement.&nbsp;</span>  
  
=== Types  ===
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== '''Types''' ==
  
There are three main types of Down's syndrome  
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There are three main types of Down's syndrome:
  
=== Causes ===
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=== Trisomy 21 ===
  
=== Typical characteristics  ===
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=== Mosaic trisomy 21 ===
  
*Flat face  
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=== Translocation trisomy 21  ===
*Short neck  
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== '''Causes'''  ==
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== '''Typical characteristics'''  ==
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*Flattened face and nose
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*Short neck with excess skin at the back
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*Small hands and feet
 
*Abnormally shaped ears  
 
*Abnormally shaped ears  
 
*Poor muscle tone (hypotonia)
 
*Poor muscle tone (hypotonia)
*Small hands and feet
 
  
=== Symptoms  ===
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== '''Symptoms'''  ==
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=== Physical  ===
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*[[Heart disease|Heart disease]]
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*Congenital heart defects
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*Coeliac disease<br>
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*Almond-shaped eyes: upward slanting eyes with a skin fold from upper eyelid that covers inner corner of the eye
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*Brushfield spots: white spots on coloured part of the eye&nbsp;
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*Hearing problems
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*[[Hypothyroidism|Hypothyroidism]]
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Young children are more susceptible to developmental delay. This may be a consequence of poor muscle tone, which impacts the ability to stand, balance, and sit normally, so they may rewach these milestones slower than other children,
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=== Intelletual and behavioural<br> ===
  
*Heart disease
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*Dementia
*Coeliac disease
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*Eye problems
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*Hearing problems
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*Skeletal intestinal problems
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*Dementia  
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*Underactive thyroid
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=== Diagnosis  ===
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== '''Diagnosis''' ==
  
=== Treatment&nbsp;  ===
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== '''Treatment&nbsp;''' ==
  
=== Related conditions and disorders  ===
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== '''Related conditions and disorders''' ==
  
=== References<br>  ===
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== '''References'''<br>  ==
  
 
<references /><br>
 
<references /><br>

Revision as of 00:10, 1 December 2015

Down's syndome is disorder caused by having an extra chromosome on chromosome 21 (referred to as trisomy 21), giving a total of 47 chromosomes instead of the normal 46 in humans. Most cases of Down's syndrome are a result of a random chromosomal defect during the formation of reproductive cells, especially egg cells. An error during gamete cell division, non-disjunction, results in the cell with an abnormal number of chromosomes. This extra chromosome copy disrupts the normal course of brain and body development, thus affecting both physical development and intellectual ability. Although individuals with Down's syndrome behave and look similar, their intellectual capability varies from mild to moderately low. As sufferers age (often about the age of 50), they may often experience a progressive decline in cognitive function, which can result in an increased risk of Alzheimer's, a neurodegenerative disease that causes dementia: a gradual loss of memory, motor skills, and judgement. 

Contents

Types

There are three main types of Down's syndrome:

Trisomy 21

Mosaic trisomy 21

Translocation trisomy 21

Causes

Typical characteristics

Symptoms

Physical

Young children are more susceptible to developmental delay. This may be a consequence of poor muscle tone, which impacts the ability to stand, balance, and sit normally, so they may rewach these milestones slower than other children,

Intelletual and behavioural

Diagnosis

Treatment 

Related conditions and disorders

References


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