Down Syndrome
Genetic disorders are caused by anormalities in the DNA
By. Isabella Endara, Emilia Sosa, Adam Finnegan
Table of Contents
Description of Down syndrome ............................................................................................................ 3
Symptoms ..................................................................................................................................................... 3
Types of Down syndrome ....................................................................................................................... 3
Who can be affected by Down syndrome? ........................................................................................ 3
Treatments ................................................................................................................................................... 4
Interesting Facts......................................................................................................................................... 4
Bibliography ............................................................................................ Error! Bookmark not defined.
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Description of Down syndrome
Down syndrome is a genetic condition in which a person has 47 chromosomes instead
of 46. An individual with Down syndrome inherits all or part of an extra copy of
chromosome 21. John Langdon Down, a British physician, discovered Down syndrome.
When karyotype techniques were discovered in 1950, the observation and study of
abnormalities in chromosomal number or shape became possible. Down syndrome causes
delays in physical and intellectual development and also health issues. There is a possibility
of 1 in 800 to 1 in 1000 born infants of having this genetic disorder (Slightham, 2012) (Leja,
2010).
Symptoms
Symptoms include mental retardation, unique facial characteristics, and health
problems. All these symptoms can range from mild to severe. Mental retardation issues can
include delayed development as an individual. For example, people with Down syndrome
have attention problems, compulsive behaviors and bad speech skills. Children with Down
syndrome have distinct features like: short neck, Protruding tongue, small ears, poor muscle
tone, short hands, short height and flattened face. Some of the health problems include heart
failure, and digestive abnormalities; moreover, they can develop leukemia and Alzheimer
(Conditions Down syndrome, 2012) (Mayo Clinic Staff, 2014).
Types of Down syndrome
There are three types of Down syndrome: trisomy 21, translocation and mosaicism.
Trisomy 21 means there is an extra 21 chromosome in each cell; ninety-five per cent of
people with Down syndrome have trisomy 21. In translocation, during cell division, a part of
the number 21 chromosome breaks off and attaches to another chromosome, usually the
number 14 chromosome. Three per cent of people with Down syndrome have translocation
pattern. Approximately two per cent of people with Down syndrome have mosaicism. In this
case, a faulty cell division occurs in one of the early cell divisions after conception. This
happens because of nondisjunction, a malfunctioning during meiosis. In this error
homologous chromosomes or sister chromatids fail to separate causing that some cells have
46 chromosomes and others have 47. (The Canadian Down Syndrome Society, 2009).
Who can have Down syndrome?
Down syndrome cases are not inherited; however, there are certain parents that have a
greater risk of giving birth to a child with Down syndrome. For example, women age 35 and
older, males 50 and older, people with a family history of Down’s syndrome, people who
carry the genetic translocation. As the age of the mother increases the possibility of having a
Down syndrome child also increases. At age 30, for example, a woman has about a 1 in 1,000
chance of conceiving a child with Down syndrome, then increases to about 1 in 400 by age
35. (Nemours, 2008)
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Treatments
There is no specific treatment for Down syndrome, but patients need medical
treatments because of their diseases. Treatments available for patients with Down syndrome
are physical and educational therapies and heart surgeries. Many babies who have Down
syndrome do not have good muscle tone, which makes it harder for them to roll over and
walk. Physical therapy can help with these problems. Babies born with Down syndrome have
a heart defects. Therefore, all newborns with Down syndrome have their heart checked. If the
infant is detected with a severe heart condition then early surgical repair may be done. Down
syndrome individual tend to have a slow development of areas such as, language, intellectual
abilities, and social and adaptive skills educational therapies help reinforcing these skills
(Leja, 2010).
Interesting Facts
 People with Down syndrome were killed, abandoned or ostracised from society
in the 19th century and now they attend to normal schools and have jobs (Crnic, 2008).
 In 1983, the average life expectancy of a person with Down syndrome was a mere 25years-old. Today, it’s 60 (Crnic, 2008).
 People with Down syndrome have physical and intellectual delays from birth but
there is a wide variety of abilities within the population that are impossible to predict
ahead of time (Crnic, 2008).
Bibliography
Conditions Down syndrome. (2012, June). Retrieved March 8, 2015, from Genetics Home
Reference: http://ghr.nlm.nih.gov/condition/down-syndrome
Crnic, L. (2008). Facts and FAQ About Down Syndrome. (Global Down Syndrome
Foundation) Retrieved March 9, 2015, from Global Down Syndrome Foundation:
http://www.globaldownsyndrome.org/about-down-syndrome/facts-about-down-syndrome/
Leja, D. (2010, June 12). Down Syndrome (Trisomy 21). Retrieved March 9, 2015, from
National Human Genome Research Institute:
http://www.genome.gov/dmd/img.cfm?node=Photos/Graphics&id=85155
Nemours. (2008). Down Syndrome. (The Nemours Foundation) Retrieved from Kids Health:
http://kidshealth.org/parent/medical/genetic/down_syndrome.html#
Mayo Clinic Staff. (2014). Diseases and Conditions. (Mayo Foundation for Medical
Education and Research) Retrieved from Mayo Clinic: http://www.mayoclinic.org/diseasesconditions/down-syndrome/basics/symptoms/con-20020948
Slightham, C. (2012, July 2). Overview Down Syndrome. Retrieved March 8, 2015, from
Healthyline: http://www.healthline.com/health/down-syndrome#Overview1
The Canadian Down Syndrome Society. (2009, June 9). Types of Down syndrome. Retrieved
March 9, 2015, from Canadian Down Syndrome Society:
http://www.cdss.ca/information/general-information/types-of-down-syndrome.html
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