Causes of down syndrome

A genetic disorder that causes permanent mental retardation and developmental delays, among other problems, Down Syndrome, affects people in different ways; meaning it can be very severe in one individual, and not so severe in another. It is the most common cause of severe learning disabilities in children. Since experts have been studying this condition for a very long time, there are great interventions that can be done early on so a difference can be made in the lives of those affected by Down Syndrome. There are known causes to the condition.


A little science lesson: human cells generally contain 23 pairs of chromosomes; one chromosome from each pair comes from your mother, and the other comes from your father. That’s where we get our genes. In the case of Down Syndrome, there are three genetic variations that can result in this abnormality. All of the problems stem from chromosome 21; also in all three, there is some degree of extra genetic material from this chromosome 21. It’s this extra DNA that results in the characteristic features of Down Syndrome. The cause isn’t any more difficult than that; it’s a matter of understanding the genes and their distribution. Also, Down Syndrome is not typically inherited; it is just due to a spontaneous mistake during cell division. It is important to pay attention to your risk factors for having a child with Down Syndrome: advanced maternal age, having had one child already with the condition, and one parent being a carrier of the genetic translocation for Down Syndrome, are all factors that can increase the risk.

Trisomy 21. The majority of Down Syndrome cases, about 90%, are caused by trisomy 21. What happens is, the child affected by it has 3 copies (instead of 2) of chromosome 21 in all of their cells. It is due to the abnormal cell division during the development of the sperm cell or egg cell.

Mosaic Down Syndrome. This is a rare form of Down Syndrome. A child affected may have only some cells with an additional copy of chromosome 21. It is due to atypical cell division after fertilization.

Translocation Down Syndrome. This type of Down Syndrome occurs when part of chromosome 21 becomes attached (translocated) onto another chromosome, before or at conception. These children have the normal 2 copies, but with some additional material from chromosome 21 stuck to the pair. This form is also very uncommon, but it is the only form that can (not necessarily that it will) be passed from parent to child.

Physical characteristics are very obvious when it comes to identifying a child or an adult with Down Syndrome. There are common facial features—flattened facial features, protruding tongue, small head, upward slanting eyes, unusually shaped ears, poor muscle tone, broad/short hands, relatively short fingers, and excessive flexibility—that one with Down Syndrome will have.

Living with Down Syndrome
It is possible that complications could result from an individual having Down Syndrome: heart defects, risk of developing leukemia, risk for getting infectious diseases, dementia, sleep apnea, and obesity are among them. Mental retardation, usually mild, is also not at all uncommon. On the other hand, if the complications are few in number for any given individual, life expectancy is not deterred to a large extent. Many people with Down Syndrome can live to age 50 and beyond (which is way ahead of what it used to be), due to early interventions and having better care available. Getting specialized help from different medical fields—pediatric cardiologist, pediatric gastroenterologist, pediatric endocrinologist, developmental pediatrician, audiologist, physical therapist, speech pathologist, and an occupational therapist—will be very beneficial if done as soon as possible.

Last updated on Nov 20th, 2010 and filed under Mental Health. Both comments and pings are currently closed.

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