Saturday, 19 May 2012

Down Syndrome


Down Syndrome
Down Syndrome is a chromosomal condition characterized by the addition of either half or whole of an extra chromosome. Chromosomes are strands of DNA (deoxyribonucleic acid) and proteins which are present in every cell of the body and make up our individual genetic material. Down Syndrome affects 1 in every 800 babies born. The extra genetic material can impair the mental and physical development in a child although the extent of this impairment varies from patient to patient (Gavin, 2012). With current research continuing, the possibilities of minimizing the risk of Down Syndrome will increase.
Down Syndrome is the most common chromosomal disorder in the world. Our cells divide in two ways, firstly is ordinary cell division which is called mitosis in which our body needs to grow. Secondly is in the ovaries and testicles where meiosis occurs. This cell division consists of one cell splitting into two creating sperm and egg cells (refer to figure 1).

Figure 1: Mitosis and Meosis

Normally during conception 23 chromosomes from the mother and 23 chromosomes from the father are inherited, totaling to 46 chromosomes, and these chromosome contain genetic information. Recent research suggests that in the majority of Down Syndrome cases there is an ovarian nondisjunction during meiosis and he child will obtain an extra chromosome 21 for a total of 47 chromosomes rather than 46 as mentioned earlier (refer to figure 2). A possible cause for this is maternal age although the exact cause is not yet known (Gavin, 2012). 





                                                Figure 2: Down Syndrome Chromosomes

The life expectancy of an individual with Down Syndrome is usually around 50 years of age. This is quite low due to almost every system in their bodies being at risk from the effects of Down Syndrome (Schoenstadt, 2012). The exact effects of Down Syndrome are still not known as chromosome 21 codes for approximately 360 proteins although there are some common health problems, such as decreased brain size, congenital heart disease and lens defects. Individuals with Down Syndrome also suffer from increased purine levels which can lead to mental retardation and immune deficiencies. Purine is an organic compound that contributes to the contents of RNA and DNA. As well as health problems there are some physical attributes that are common in Down Syndrome patients for example slanted eyes, shorter neck and shorter limbs (Cunningham, 2008).
There are treatment and therapies available for Down Syndrome patients including physiotherapy to help strengthen muscles, surgery for heart disease  and regular check ups and screening to prolong the life of the individual (Cifra-Bean, 2012). Research in the field of genetics is very promising although it must only be considered in the future as the genes need to be identified and their function be determined before any radical medical procedures are recommended. Interactions between genes can also be a key factor to help minimizing Down Syndrome (Cifra-Bean, 2012).
It is a very promising time in research in Down Syndrome as the advent of the completion of the human genome project is more understood and practiced than ever before. Future research could help improve life expectancy, symptoms and possibly even help repair the chromosome 21 in this devastating chromosomal disorder.

Reference List

Cifra-Bean. L, 2012 National Down Syndrome Congress, Current Research in Down Syndrome, 13th March 2012. <http://www.ndsccenter.org/resources/documents/current.php>
Cunningham. C, 2008, Down Syndrome for New Parents, “What are the Physical Characteristics of Down Syndrome?” , 12th March 2012. <http://www.downsyn.com/whatphys.php>
Gavin, M.L, 2012, Kids Health, “About Down Syndrome”, 13th March 2012. <http://kidshealth.org/parent/medical/genetic/down_syndrome.html#>
Kola. I, 1989 “Reproduction, fertility, and development,” vol. 1, no. 1, pp. 81-82

Leshin.L, 2003, Down Syndrome: Health Issues, “Trisomy 21: The Story of Down Syndrome”, 16th March 2012. < http://www.ds-health.com/trisomy.htm>
Schoenstadt. A, 2006, eMed TV, “ Down Syndrome Effects”, 14TH March 2012. <http://down-syndrome.emedtv.com/down-syndrome/down-syndrome-effects.html>

by Holly Roberts-Simmonds


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