The Different Types Of Gene Testing Biology Essay


Gene testing is a complex process of examining and analyzing individual genes in cases like there is a family history of one specific disease, or if the person shows symptoms of a genetic disorder, or even if the person is concerned about passing on a genetic problem to this/her children.

It involves examining a person's DNA taken from cells in a sample of blood or, from other body fluids or tissues -and requires techniques to examine the genes for some abnormality that is related or marks a disease or disorder.

What are different types of gene testing?

Preimplantation genetic diagnosis

(check the blue box, Screening Embryos for Disease)

Prenatal diagnostic testing

It is genetic testing of a fetus, and it is done when there is a risk of giving birth of a child with genes associated with mental retardation or physical deterioration.

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Newborn screening

Late-onset testing

What are some of the advantages of gene testing?

Clarify a diagnosis and direct a physician toward appropriate treatments

Allow families to avoid having children with devastating diseases

Identify people at high risk for conditions that may be preventable.

What are some genetic diseases that are very common in our days ?

1)Huntington's disease

Huntington's disease is a rare neurodegenerative, genetic disorder that severely affects the brain. Huntington's disease results in the destruction of certain cells in the brain. Huntington's disease is a seriously disabling and devastating disorder that progressively damages and destroys a person's ability to think, move voluntarily, and function independently


The Common Symptoms

poor memory

depression and convulsion

uncontrolled movements

Some Important Statistics

Prevalance of Huntington's Disease: estimated 3-7 per 100,000 people of European ancestry suffer from Huntington disease, Genetics Home Reference website

Prevalance Rate: approx 1 in 33,333 or 0.00% or 8,160 people in USA [about data]

Incidence Rate: approx 1 in 175,390 or 0.00% or 1,550 people in USA [about data]

Prevalance of Huntington's Disease: About 30,000 Americans have HD and about 150,000 more are at risk of inheriting the disease from a parent. (Source: Genes and Disease by the National Center for Biotechnology)


2)Down syndrome

A genetic chromosomal syndrome affecting physical features and usually causing mental retardation. It is caused by having an extra third copy of chromosome 21, usually by a random error in the mother's egg, it can be termed as a developmental disorder which results from an additional copy of chromosome and It is more common in babies whose mothers gave birth at an older age - that is, 35 years and above


The Common Symptoms

Physical abnormalities:

Flattened face

Snub nose

Flattened nasal bridge

Upward slanting eyes

Short neck

Enlarged tongue

Protruding tongue

Abnormally shaped ears

Deep palm crease - a single

Deep transverse crease of the palm of the hand

Poor muscle coordination

Short stubby hands

Short stubby feet

Slow physical growth

Infant not crying much

Thyroid symptoms :

Congenital hypothyroidism

Enlarged thyroid

Autonomic disturbances

Mental symptoms:

Mental retardation

Developmental delay


Some Important Statistics

The following are statistics from various sources about the complications of Down Syndrome:

40 to 50% of children with Down syndrome have congenital heart defects in the US (Association for Children with Down Syndrome)


The following are statistics from various sources about the survival rate for Down Syndrome:

People with Down syndrome typically live to about 55 years or longer in the US (Association for Children with Down Syndrome)


3) Sickle Cell disease

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Sickle cell disease is a genetic disorder in which the red blood cells that freely transport oxygen from the lungs to the rest of the body become shaped like sickles rather than disks. As the hemoglobin molecules do not form properly, oxygen is restricted from reaching the organs such as lungs, heart, spleen, liver and kidneys. Sickle cell disease is caused when both parents pass on a defective copy of the gene to their offspring.

The Common Symptoms

Abdominal or chest pain or pressure

Bone pain

Delayed puberty

Excessive thirst


Frequent urination

Loss of vision of changes in vision

Rapid heart rate (tachycardia)

Spontaneous, painful and persistent erections (priapism)

Symptoms of anemia, such as dizziness, headaches, and poor circulation

Ulcers of the legs and skin

Serious symptoms that might indicate a life-threatening condition

Chest pain, chest tightness, chest pressure, palpitations

Confusion or loss of consciousness for even a brief moment

Difficulty breathing or rapid breathing

Garbled or slurred speech or inability to speak

High fever (higher than 101 degrees Fahrenheit)

Loss of vision or changes in vision

Severe abdominal pain

Severe fatigue, weakness, or shortness of breath

Some Important Statistics

SCD affects an estimated 70,000 to 100,000 Americans.

The disease occurs in about 1 out of every 500 African Americans births.

The disease occurs in about 1 out of every 36,000 Hispanic Americans births.

Sickle cell trait occurs in about 1 in 12 African Americans.


Sickle cell-related death among African-American children less than 4 years of age fell by 42% during 1999 to 2002. This coincides with the introduction of a vaccine that protected against invasive pneumococcal disease in 2000. [Read summary]

Relative to the rate for 1983-1986, the SCD mortality rate for 1999-2002 decreased by:

68% at age 0 to 3 years

39% at age 4 to 9 years

24% at age 10 to 14 years

4)Alzheimer's disease

Alzheimer's disease is a seriously disabling neurodegenerative disease of the brain. Alzheimer's disease progressively damages and destroys such cognitive processes as memory, orientation, and speech. Alzheimer's disease is not curable and is the most common cause of dementia, a progressive and permanent loss of cognitive and mental performance. the disease strikes the person around the age 65 years . , There is no cure for Alzheimer's. .

The Common Symptoms

As the disease destroys brain cells patients start:

losing their ability to think clearly.

forget even the simplest things such as their names and address

difficulty learning and remembering new information,

deterioration in personal hygiene and appearance,

Progressive difficulty in communication and severe deterioration in memory, language, and motor function result in a loss of coordination and an inability to write or speak.

Some Important Statistics

Each day on average, 1,252 people are diagnosed with Alzheimer's disease.

Alzheimer's disease was the sixth leading cause of death across

all ages in the United States in 20065.4 million people have Alzheimer's disease.

Alzheimer's disease is the fifth-leading cause of death for those aged 65 and older.

Further Links

40% . . . Why?

Genetics Research Funding Proposal

Sci-Thinking project 2011

Our proposal | Funding Reasonings | About Us

Our Proposal


What IS cloning?

It is a process by which anything from a cell to a whole organism is identically replicated.

Potential benefits, implications & Solutions

Therapeutic cloning ( a process in which embryonic clones are produced from DNA) can use embryos to grow stem cells which are often referred to as “ human repair kits” [ Source: How Stuff Works] since they are used to generate healthy organs and neurons to cure severe diseases such as heart & liver failures and even Alzheimer's. This process would be less risky compared to organ replacement by a donor since the possibility of tissue rejection is completely eliminated.

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Reproductive cloning can aid infertile couples since technology would allow them to produce children who have similar DNA and therefore similar characteristics to them. Although most evidence suggests that reproductive human cloning poses dangers to children produced in the process, there are many solutions underway to create more reliable techniques. Improved research and technological advancement make it easier to identify the defective embryos before implantation into mother's uterus. However, further funding is needed in order to boost research trials which would secure the process and make it safer.

Cloning means that hybrids with specific desirable characteristics can be formed. These hybrids would assist in advancing the search for cures for diseases like Parkinson's & Alzheimer's.

Would assist in other aspects of genetics such as genetic testing and genetic engineering.

It is obvious why funding is needed in this field of research. This research area is still in its infancy and the potential benefits reaped would be countless. Therefore it is of extreme importance to provide it with sufficient financial backup. That is why we have decided to allot 30%.

30% . . .. .Why?

Genetics Research Funding Proposal

Sci-Thinking project 2011

Our proposal | Funding Reasonings | About Us

Our Proposal

Preserving Biodiversity

According to the genetic changes that always happen during the life of living organisms, biodiversity plays a very important role to keep the variety of genes on the earth. This field of research concerns about preserving the variations of genes in order to give the chance for the living organisms to live and adapt with the environmental and climatic changed that happen gradually. It gives reasoning for the decrease that might happen in the population of certain animal. It also gives ways to increase the endangered living organisms. One example about endangered organisms, the giant panda which has low possibility to live and it has few members exist. This animal would extinct unless something is done! There are also threatened living organisms that face a problem of decreasing its population and it may become endangered soon. All these animals face a genetic adaptation problem and it wouldn't be solved unless having a research field like preserving biodiversity.

Another idea to be mentioned is that people take different approaches when making the case forpreserving biodiversity. Some argue that biodiversity is important to ensure access to new medications, while others emphasize the importance of maintaining healthy ecosystems for recreational purposes such as fishing or camping. Of course, many people use more than one argument when calling for biodiversity protection.

Five major categories of these arguments are as follows:

Economic: It can help people make lots amounts of money or keep them from losing money.

Recreational: People love outdoor activities like fishing and backpacking, which would not be possible if ecosystems were destroyed.

Human health: Biodiversity can help people find better cures for illnesses.

Human rights: If biodiversity is protected, indigenous people can continue to live in their native lands.

Spiritual/intrinsic value: Biodiversity should be preserved for its own sake," "Animals and plants have a right to live," and "People rely on wild places and creatures for spiritual fulfillment

That is why we have decided to allot 15%.

Further Link:

15% . . . Why?

Genetics Research Funding Proposal

Sci-Thinking project 2011

Our proposal | Funding Reasonings | About Us

Our Proposal

Genetically Engineered Food

Genetically engineered food

Genetically engineered food is the process of transferring genes to the plant that will allow it to grow during droughts, low soil fertility and produce large amount of crops without being affected by any pests. With the growing in the world's population there wouldn't be enough food to feed everyone. Kenya for example needs to produce three times more maize to feed its population in 2050 than it does today. These genetically engineered crops will be able to grow in harsh conditions whether it's too hot or cold. Moreover, genetically modified plants can produce drugs that are too expensive to manufacture and contain nutrients in them they lacked before, such as increasing the level of vitamin A in rice which is a critical nutrient in preventing diseases. In addition, with the future development the GM plants they can reduce the levels of allergens in crops that caused allergies such as in peanuts or potatoes. Furthermore, there won't be the necessity of using pesticides, as these modified plants can have a gene that kills the pest, so this will be better for the environment as the insecticide contaminates the soil, water and other creatures including humans. For example the BT is a protein extracted from a bacteria that is inserted in the plant and injures the gut of the insect (European borer), keep in mind that the BT breaks down quickly so it won't harm the environment nor does it harm any other insect or mammals including humans. In addition, BT saves a lot of money as the farmer doesn't need to get pesticides. By reducing the amount of the European borer using GN plants we would save a lot of money and increase crop yield, as in 1996 the corn borer cost farmers 1 billion dollars out of 25 billion dollars in crops. So the plants with the resisting gene to pests, kills only the pest not the predator for these pests, beneficial pests, fish and mammals.

On the other hand there are some limitations that prevent genetic engineering to be fully utilized and benefited from. DNA and genetic engineering are issues, humans are constantly discovering. For example If we insert the protein in the DNA of the plant we won't know if the protein is in the active part of the DNA or not, as most of the DNA is inactive and we lack the knowledge today that will enable us to successfully insert the gene in the plants DNA. Moreover we can accidently cause certain genes that are inactive to be active; these genes may have harmful effects on humans as they may produce toxins that wouldn't of been there if we wouldn't of intervened. We may also cause unexpected allergies that may be more allergenic than proteins produced by the original DNA sequences.cannot predict whether the GM crops will cause any harmful side effects, we cannot test it by giving an overdose such as in drugs, as it will cause imbalance within the diet but if we know more about the DNA we can predict what the future holds. With understanding the DNA and genetic engineering we can overcome these limitations and we can have more promising outcomes than today. The triumph of having genetically modified crops with no defects is important as there are countries who are in need for the GM crops to feed its ever demanding population, with harsh conditions, as the world is having more trouble with fresh water. The following points are the advantages if the modified crops defects are eliminated by extensive researches.

More food and its essential for survival

Helps in medicine as plants can produce expensive drugs

Plants growing in harsh conditions were water is scarce, poor soil and extreme cold or hot weather.

Having more nutrients that was had before

More crop yield as genes can cause the plant to produce more

No need to use insecticides as there are anti resisting plants, benefiting the environment and reducing cost for pesticides.

Reduce allergens in fruits.

That is why we have decided to allot 15%.

Further Links

15% . . . Why?

Funding Reasoning

About Us

Genetics Research Funding Proposal

Sci-Thinking project 2011

Our proposal | Funding Reasonings | About Us

Funding Reasoning

Our Proposal

About Us

We are a group of students in enrolled in the Scientific Thinking course in the American University in Cairo. We worked together on a project of framing a funding proposal in favour of funding different research fields related to genetics.

Team Members:

Ahmed Shalaby

Hadeer AbdelSamad

Sara Fawzy

Rana Mohamed Farid Hegazi

Genomic research

“The role of genomic research is indispensable in the ever challenging fields of diagnosis and treatment of genetic disorders, infectious diseases and non communicable diseases. Main areas of genomics research include genetic testing, gene therapy, reproductive genomics, genetic databanks and pharmacogenomics. Researchers and policy makers alike are continuously assessing the value of this research in terms of its utility and cost-effectiveness for public health.”….. WHO

Genetic Testing for Diseases


Preserving Biodiversity

Genetically Engineered Food

“Aproximately 3 to 4 percent of all babies are born with a genetic disease or birth defect, according to information provided by Net Wellness”

Screening Embryos for Disease Preimplantation genetic diagnosis (PGD)

is a test that screens for genetic flaws among embryos used in in vitro fertilization. With PGD, DNA samples from embryos created in-vitro by the combination of a mother's egg and a father's sperm are analyzed for gene abnormalities that can cause disorders. Fertility specialists can use the results of this analysis to select only mutation-free embryos for implantation into the mother's uterus.

Before PGD, couples at higher risks for conceiving a child with a particular disorder would have to initiate the pregnancy and then undergo chorionic villus sampling in the first trimester or amniocentesis in the second trimester to test the fetus for the presence of disease. If the fetus tested positive for the disorder, the couple would be faced with the dilemma of whether or not to terminate the gnancy. With PGD, couples are much more likely to have healthy babies, Although PGD has been practiced for years, only a few specialized centers worldwide offer this procedure.

In gene tests, scientists scan a patient's DNA sample for mutated sequences. A DNA sample can be obtained from any tissue, including blood. For some types of gene tests, researchers design short pieces of DNA called probes, whose sequences are complementary to the mutated sequences. These probes will seek their complement among the three billion base pairs of an individual's genome. If the mutated sequence is present in the patient's genome, the probe will bind to it and flag the mutation. Another type of DNA testing involves comparing the sequence of DNA bases in a patient's gene to a normal version of the gene. Cost of testing can range from hundreds to thousands of dollars, depending on the sizes of the genes and the numbers of mutations tested.