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Genetic Mutations and Down Syndrome

Biological Science 2013
by

Jessica Woods

on 29 April 2013

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Transcript of Genetic Mutations and Down Syndrome

Jessica Woods, Travis Langlois, Momena Sultani The Basics Future Research: Trisomy Mouse Models Future Research 5 Ways the Environment Can Damage DNA. (n.d.). Find Science & Technology Articles, Education Lesson Plans, Tech Tips, Computer Hardware & Software Reviews, News and More at Bright Hub. Retrieved March 22, 2013, from http://www.brighthub.com/science/genetics/articles/34904.aspx
Bailey, R. (n.d.). Gene Mutation. Biology. Retrieved March 22, 2013, from http://biology.about.com/od/basicgenetics/ss/gene-mutation.htmBianch, N. (n.d.). Control of Spontaneous Mutation Rates. Control of Spontaneous Mutation Rates. Retrieved March 21, 2013, from https://www.bio.cmu.edu/courses/03441/TermPapers/96TermPapers/spontaneous/spontaneous.htmlCures for Down Syndrome. (n.d.). Down Syndrome Home Page. Retrieved March 22, 2013, from http://down-syndrome.emedtv.com/down-syndrome/cures-for-down-syndrome.htmlDown Syndrome. (n.d.). Learn.Genetics. Retrieved March 22, 2013, from http://learn.genetics.utah.edu/content/disorders/whataregd/down/Down Syndrome . (n.d.). KidsHealth - the Web's most visited site about children's health. Retrieved March 22, 2013, from http://kidshealth.org/parent/medical/genetic/down_syndrome.htmlGoldman, S. (2010). Determing the amount, timing and causes of mortality among infants with Down syndrome. Journal of Intellecutal Disabilty Research, 55, 85-94.Leshin, L., M.D.., & F.A.A.P.. (n.d.). Down Syndrome: Health Issues - Medical Essays and Information. Down Syndrome: Health Issues - Medical Essays and Information. Retrieved March 22, 2013, from http://www.ds-health.comMohammad, A., Khan, I., & Khan, M. Q. (2012). HYPOTHYROIDISM IN CHILDREN WITH DOWNS SYNDROME: A HOSPITAL BASED STUDY. 10(1), 97. Retrieved March 21, 2013, from http://ehis.ebscohost.com/eds/detail?vid=4&sid=052ed13c-901f-4a3c-ad04-569cd301d604%40sessionmgr4&hid=5&bdata=JnNpdGU9ZWRzLWxpdmU%3d#db=a9h&AN=80214831Nagy, G. (2012). Lower risk for Down syndrome associated with longer oral contraceptive use: a case-control study of women of advanced maternal age presenting for prenatal diagnosis. Contraception, 87, 455-458.Nobelprize.org. (n.d.). Nobelprize.org. Retrieved March 22, 2013, from http://nobelprize.orgResearch FAQs - Down Syndrome Research and Treatment Foundation. (n.d.). Home - Down Syndrome Research and Treatment Foundation. Retrieved March 22, 2013, from http://www.dsrtf.org/page.aspx?pid=386 -A mutation is an error in DNA that causes a problem in the function of the proteins produced by a cell.

-Chemicals, random mutations, environmental influences, ultraviolet light from the sun, radiation, and errors during the replication process of DNA. Other factors that can be affected by mutations are protein synthesis which can dramatically change the function or ability of a cell.

-Gene mutations are alterations in the sequence of nucleotides in DNA and the segments of chromosomes located on the chromosomes are genes. Mutations can cause changes that affect single nucleotide pairs or segments of DNA chromosomes. In order to improve the lives of Down syndrome patients and their families researchers are looking to improve the cognitive function of patients by:
-determining what pathways in particular are affected
-identify compounds that could regulate the release of specific cells which cause a decrease in cognitive function.
- new teaching strategies Mice have an extra chromosome that is very similar to chromosome 21 in humans. With this information researchers are using chromosome engineering to generate new trisomy mouse models that will represent various stages of Down syndrome.
Possible results: discovery of better ways of treating the signs and symptoms
-discovery of ways to treat/ slow progression
Problem: high cost




Ultimately researchers would like to get samples of brain tissue from Down syndrome patients in order to test their theories. Current research states that scientists have found the genes that are believed to be the cause of Down syndrome.
Future research objectives are to be focused on defining, in detail, the abnormalities in brain structure as well as the function that could be responsible for cognitive problems in Down syndrome patients and explaining their genetic and cellular basis of this disease Genetic Mutations and Down syndrome Translation When DNA is transcribed into RNA, the RNA then translates it to make the proteins. During translation, many nucleotide sequences can get altered which can often lead to non-functioning proteins. Types of gene mutations -Point Mutations
-Base-pair insertions of deletions Point Mutations -Includes silent mutations, missense mutations, and nonsense mutations Silent mutations -Do not change the protein that is being produced
-Harmless Missense mutations -Alter nucleotide sequences
-Causes a change in the amino acid that is made
Alters protein production and function Nonsense mutations -Alters the nucleotide sequence to produce a stop codon
-stop codon stops the process of translation
-results in a nonfunctional protein Factors causing mutations in DNA Gene mutations Environmental effects on Mutations -Environment can affect DNA due to different forms of radiation
-Sunlight and UV radiation
-Environmental chemicals
-Environmental tobacco smoke -The human body needs sunlight for making proteins such as Vitamin D
-Exposure to long periods of sunlight can cause damage to the cellular systems and the DNA
-Environmental ties in because humans are always exposed to harmful environmental conditions such as butadiene from rubber factories and vinyl chloride
-Tobacco smoke damages the DNA in humans because it has a tar phenolic compound that causes the DNA to have breaks Down Syndrome -Also referred as as trisomy 21
-When a child gains an extra chromosome during development
-Occurs more frequently with older woman around the ages of 35 and older
-Affects how a child develops mentally and physically
-Screening tests and diagnostic tests are used to detect Down Syndrome in a fetus.
-Diagnostic- if fetus has the condition
Screening-estimates the risk for the fetus having DS History of Down Syndrome -First discovered in 1866 by a man named John Langdon Down
-Down noticed a set of similarities in a group of children
-originally called "mongoloid" but was changed to down syndrome in the early 1960's
-Waardenburg and Bleyer were the first to speculate that is might be due to chromosomal abnormalities
- Jerome Lejeune and Patricia Jacobs discovered that trisomy 21 was affected in 1959
- Most prevalent cause is non-disjunction Non-Disjunction -Occurs during cell division
- Occurs when an egg or sperm has a unusual amount of chromosomes merges with a normal chromosome
- Cause of 95% of Down syndrome cases Current Research: Down Syndrome Down syndrome occurs in 1 in 800 live births. It also is the most common genetic cause of mental retardation. Current research is focused more on the prevention and understanding of the disease. They also aim to improve the overall life of people affected by down syndrome. Current Research: Prevention of
Down Syndrome If the mother is over the age of 35 then the risk of having a baby with Down syndrome is greatly increased. This is due to the accumulation of trisomy 21 oocytes on reserved in elderly women.
Purpose of study: to prove that lowering the number of unnecessary ovulations in women each month could allow more unaffected oocytes to be saved, reducing the chances of a Down syndrome baby.
Process: perform a genetic amniocentesis in 5222 pregnancies
- collect data, regarding factors that effect the number of ovulations, from 37 patients where fetal Down syndrome was confirmed
Conclusion: patients with "trisomic fetuses" did not use contraceptives as long as mothers that did not, and that in fact the number of ovulations was higher in mothers with affected babies. Current Research: Hypothyroidism in Children with Down Syndrome Hypothyroidism: is a medical disorder in which your thyroid gland doesn't produce enough of certain important hormone. This is commonly found in Down syndrome patients.
A recent study was done at the Lady Reading Hospital in Peshawar, Pakistan.
Purpose: to figure out the frequency of hypothyroidism in Down syndrome patients.
Process: 50 affected individuals were used
Conclusion: 3 out of these 50 patients had hypothyroidism

This study can aid in better treatment options. Hypothyroidism may also have an effect on
the function of the central nervous system , which may lead to other medical conditions.
The following chart shows the ages of perticipants in the study and the ages of their mothers. Current Research: Mortality among Infants with Down Syndrome - Done by researchers at the Tennessee Department of Health.
Purpose: to examine the amount, timing and causes of death among infants with Down syndrome
Process: included analyzing and comparing birth and death records from 1990-2006
- Used 1305 infants: 54.8% were male and 45.2% were female
Conclusion: many affected infants die within the "neonatal period" (between 28 days and 1 year)
-Down syndrome babies are 8.3 times as likely to die than unaffected infants
- 97 out of 1305 infants died: 26.8% within the first day, 17.5% within 28days compared to the unaffected population: 66.6% died within the first month, and 37% of deaths on day one.
- most of Down syndrome deaths were related to heart and respiratory conditions

This study could lead to better infant care and understanding of this disorder. Future Research:
Cognitive Function Future Research: Prevention In order to aid in prevention, three primary prevention strategies are suggested:
1) Avoid reproduction at advanced maternal age: after the age of 30 your chances become doubled
2) pre-implantation genetic diagnosis for couples who are at high risk: produces a reasonably high pregnancy rate with an extremely lower risk
3) Folic acid supplementation: use of sufficiently high dose of folic acid

All three strategies are used but the most affective one is maternal age. History of Genetic Mutations -In 1859 Darwin published "The Origin of Species" in which he postulated the new theory of survival of the fittest.

-Gregor Mendel is referred to as the father of genetics and he paved way to predicting the characteristics of offspring.

-In 1869 DNA was discovered from cells in pus from open wounds from a scientist named Friedrich Miescher. The scientist Miescher separated the cells into a protein and an acid molecule by 1874 which was known as nucleic acid.

-Miescher succeeded in isolating nuclein from salmon spermatozoa, similar in properties to the nuclein of leukocytes from pus, except that it was combined in salt-like form with a basic protein he called "protamin", still known by that name to-day. History of Genetic Mutations -Muller was called the father of radiation genetics
-He formulated in 1918, 1920, 1921, and 1926 where the chief principles of spontaneous gene mutations were recognized
-By 1926 Muller had hard evidence of the increased production of chromosome and gene mutation changes by X-rays.
-Published by 1927
-The information opened the door for several new types of research which includes the studies of gene mutation effect and their structural changes
-Gene mutation is not always hereditary & many devastating disorders have come from random mutations. References
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