Genetics: A photo of a fetus with trisomy 21 shows a subcutaneous fluid collection at the back of the neck. gfmer.ch
Down syndrome, or trisomy 21, is a chromosome irregularity caused by a genetic mutation in one in every 800 live births in all races and economic groups.
It is also the most frequent genetic cause of mild to moderate mental retardation and associated medical problems, and while people with Down syndrome are able to lead fulfilling and productive lives, there are many associated medical problems.
Individuals with the syndrome have a lower than average cognitive ability – often ranging from mild to moderate developmental disabilities – and often have problems registering and communicating coherent speech. A smaller number of sufferers have severe to profound mental disability.
Other health concerns for individuals with Down syndrome include a higher risk of congenital heart defects, recurrent ear infections, gastroesophageal reflux disease, thyroid dysfunctions, sleep apnea, and higher risk of spinal injury.
Individuals with the syndrome are identifiable by a number of physical characteristics, especially facial, including microgenia (a smaller than average chin), a very rounded face, macroglossia (protruding or oversized tongue), an epicanthic fold of the eyelid, up- slanting palpebral fissures (the separation between the upper and lower eyelids), a simian crease (a single instead of a double crease across one or both palms), a larger than normal space between the big and second toes, shorter limbs, poor muscle tone, and a higher propensity to be overweight.
Degrees of the disability vary, however, and while some individuals are very physically disabled, others are very able and even athletic. Similarly, degrees of mental disability vary, and the speed at which one can learn and complete tasks varies person to person.
It may difficult for some people with Down syndrome to complete simple tasks, such as feeding themselves, but others can perform more complex tasks, such as competitive sports, arts and dance.
While individuals with the genetic condition often have difficulties with verbal short-term memory, recent studies by Francis Connors and colleagues in the UK show that parental training programs can improve the working memory of those with Down syndrome.
It is therefore important for those with the syndrome to be in challenging and stimulating environments to allow their cognitive functions to improve, rather than deteriorate.
Since 2006, March 21 has been earmarked as World Down Syndrome Awareness Day (WDSD).
The date was chosen to signify the uniqueness of Down syndrome in the triplication of the 21st chromosome. The annual observance of this day aims to create awareness and understanding of the syndrome.
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