genoma- cristian chiluisa.pdf

7/28/2019 genoma- cristian chiluisa.pdf

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Whatsa

Genome?

Tere are more than 6 billion people on our

planet each a massive collection o about

100 trillion cells.

How do these cells know what to do? What

tells them to work together to keep your heart

pumping, brain thinking and bones growing?

Te answer lies in a long, winding molecule

called deoxyribonucleic acid, or DNA.

Te DNA contained within each o your cellscarries the instructions needed to build and

maintain the many dierent types o cells that

make you, you. Researchers call this complete

set o DNA instructions a genome.

Is my genome unique?

Humans come in

many shapes and

sizes, but were all

very similar at the

DNA level. In act, the

genomes o any two

people are more than

99% the same.

Still, the tiny raction

o the genome that

varies among humans

is very important. DNA variations are part o what makes each o us

unique. Tey aect the color o your eyes, hair and skin. Whats more,

they inuence your risk o disease and your response to drugs.


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So, is everything determined by my genome?

No, your DNA is just one part o the amazing puzzle o who you are.

When it comes to your health, other pieces o the puzzle include

liestyle and environmental actors, such as the ood you eat and the

air you breathe. Once we learn more about how the human genome

interacts with these actors to cause disease, we may be able to change

our habits and adapt our environment to improve our health.

Our genomes also are likely to contribute to some o the ways we eel,

think and act. But keep in mind that many other things, such as howyou were raised and your access to medical care, can inuence your

behaviors and your health.

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What does my genome do?

I you could peer inside your cells, youd see your genome contained

in 46 tightly packed bundles o DNA 23 came rom your mother

and 23 rom your ather. Tese DNA bundles, called chromosomes,

provide the instructions that enable a one-cell embryo to develop into

a 100 trillion-cell adult.

But DNA isnt just about growth. It instructs cells

throughout your lie telling them how to respond

to the oods you eat, the germs you encounter and the

pollutants to which you are exposed. Ultimately, DNA

even inuences how you age.

o understand DNAs instruction manual, lets look at

its structure. I you unwind the DNA molecule packed

into each chromosome, it looks like a twisted

ladder. Te rungs o this ladder are made rom

our types o chemical building blocks. Tese

blocks adenosine, thymine, cytosine and

guanine are abbreviated with the

letters A, , C and G.

Depending on how many o these building blocks are stacked

together and the order in which they are arranged, DNA can produce

many dierent types o organisms.

It takes about 3 billion pairs o As, s, Cs and Gs to write the

instructions needed to build a human. So, every time the human body

produces a sperm or an egg, 3 billion DNA letters must be copied and

packaged so they can be passed along to uture ospring.

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Whats a gene?

An instruction manual isnt worth much until itis read and actually used to make something.

Te same goes or your genome.

Te DNA building blocks, or letters, in

your genome combine in dierent ways

to spell out specic instructions. Still,

the language o the genome doesnt

make much sense at rst glance.

ry reading this sequence o DNA letters:

ACAGGGCAAGACGG

But i you know how to decode the string

o letters and every cell does you can

begin to see three-letter words.

A CAG GG CA AG AC GG

Whats more, these words are strung

together to make sentences, or genes,

each o which tells the cell how to make a

specic protein.

Because tens o thousands o proteins are

needed to build an entire human, your

genome contains about 20,500 genes.

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Genes atWork

So, your genome provides instructions in the form ofgenes. But exactly how are these instructions used to build

proteins?

To make a protein, a genes DNA sequence is transcribedinto a molecule called messenger RNA (mRNA). Thismolecule leaves the nucleus and enters the outer region of

the cell, called the cytoplasm. There the mRNA is read. Tinymachines called ribosomes use the information to assemble

building blocks, known as amino acids, into a protein.


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What are genetic mutations? And how do they

cause disease?

Each o us contains many slight variations in our genomes that make

us unique. Most o these variations have little or no impact on our

health. But thats not always the case.

Sometimes i a DNA letter is missing or wrong in a genes instructions,

it may produce a damaged protein, extra protein or no protein at all.

Such changes in genes are called genetic mutations.

Genetic mutations can cause serious health problems becausethey aect proteins, which are the workhorses o your body. For

example, proteins orm special scaolds that help your cells keep their

shapes. Tey serve as enzymes that help your stomach digest ood.

Te molecule that carries oxygen in your blood is a protein, as are

estrogen, testosterone and other hormones.

Te transmission o genetic mutations rom one generation to the

next helps to explain why many diseases run in amilies. I a certaindisease runs in your amily, doctors say you have a amily history o the

condition.

What genetic tests are available for diseases?

Many rare diseases, such as cystic brosis and sickle cell anemia, are

caused by mutations in a single gene. Single genes also are responsible

or some o the rare, inherited types o cancer. Over the past couple odecades, researchers have developed genetic tests to detect mutations

or many single-gene disorders. Tis has led to ways to prevent or

reduce symptoms o some o these diseases.

Genetic tests also are available to help couples learn i they carry

genetic mutations or rare diseases and i they are likely to have a child

aected by the disease. I you are interested in such tests, a good place

to start is talking to a genetic counselor or an obstetrician.

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Most genetic tests involve taking a small sample o blood or saliva and

sending it to a lab. At the lab, technicians puriy DNA rom the sample

and use various technologies to see i it contains a specic geneticmutation. One approach involves placing DNA on tiny chips, called

microarrays, that resemble the chips used in computers.

Te situation is ar more complex or most common diseases, such as

cancer, diabetes and heart disease. Researchers are nding that multiple

genes along with liestyle and environmental actors interact

to determine the risk o these and many other disorders. Another

complication is that our genomes also contain genetic variations thatprotect us against certain diseases.

So, it will take some time

beore genetic tests are

developed to provide a

complete picture o your

risks or common diseases.

Until then, one important

thing you can do or

your health and your

amilys health is to

collect your amily history.

Knowing what diseases

have aected your blood

relatives can help yourhealth care provider

To organize and creategauge your risk or certain

your family health history, use theU.S. Surgeon Generals free Web tool at: diseases and suggest ways

www.surgeongeneral.gov/familyhistory to reduce that risk.

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http://www.surgeongeneral.gov/familyhistoryhttp://www.surgeongeneral.gov/familyhistory


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What will genome research mean for me?

Walk into any drugstore and youll nd drugs developed with the idea

that most drugs work pretty much the same way in all people. But

genome research has helped to reshape that thinking. Depending on

your genetic make-up, some drugs may work aster or slower or

produce more or ewer side eects in you than they do in others.

Tanks to genome research, doctors soon will be able to use

inormation about your genes to choose those drugs and drug dosages

that are most likely to work well in you.

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Tis research will also lead to the development o better drugs. Rather

than screening or chemicals with broad action against a disease,

researchers are now usinggenomic inormation to

design drugs targeted at

specic pathways involved

in the disease. Te hope is that

this new generation o drugs will

work better and cause ewer side

eects than current treatments. Sucheorts are already starting to pay o,

as seen by the success o gene-based

drugs in the treatment o leukemia and

other cancers.

But thats not all. Tis new, more

individualized approach to health care will

extend ar beyond the drugs you receive.Within the next decade, genetic tests are

expected to become available to predict your risk

or many common conditions. Such tests will signal

the end to the current one-size-ts-all approach to health

care. Based on the inormation contained in your genome, your health

care provider will develop more personalized strategies or detecting,

treating and preventing disease.I your genetic prole shows that you are at increased risk or colon

cancer, you might undergo more requent colonoscopy screening and

reduce the amount o meat in your diet. Or i your genome contains

variations that raise your risk o heart disease, you might exercise

more and take drugs that lower cholesterol.

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What

Lies

ahead?

Tere is bright promise on the horizon.

As researchers learn more about the

human genome, more and moregene-based tools and technologies will

appear everywhere rom the doctors

ofce to the crime lab. Progress is being

made aster than anyone ever dreamed

possible.

But is our society ully prepared

to handle these new tools andtechnologies?

Since the start o the Human Genome Project, the National

Human Genome Research Institute has devoted a signicant

part o its resources to addressing the ethical, legal and social

implications o genome research.

Among the many questions being tackled are: Who should have

access to your personal genetic inormation? What can be done

to make sure that genetic inormation is not used to discriminate

against individuals or groups? Will all sectors o society have access

to these new technologies?

On a personal level, you likely will ace some challenging issues and

decisions related to gene-based technologies and inormation over

the course o your lietime.

By learning more about your genome and what it may mean

or your uture, you have taken a major step towards preparing

yoursel or this exciting new era: Te Genome Era.

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Learn moreabout Your Genome & Your heaLth

Genetics and Rare Diseases Information Center

www.genome.gov/Health/GARD

E-mail: [email protected]

oll-ree phone (12 p.m-6 p.m. Eastern, Mon.-Fri.)

1-888-205-2311

Y: 1-888-205-3223

Tis ree service provides inormation about genetic and rare diseases.

Its Web site oers educational materials and reers people to reliable

sources o inormation. Inormation specialists are also available to

answer questions in English and Spanish.

Health Fact Sheets

www.genome.gov/Health/FactSheets

Tis series o act sheets helps health care consumers understandgenetic concepts and technologies. opics include genetic testing,

genetic counseling and overviews o specic genetic disorders.

Genetics Home Reference

http://ghr.nlm.nih.gov

Tis online reerence, created by the National Library o Medicine

at NIH, provides consumer-riendly inormation about the eects o

genetic variations on human health. It contains inormation on thegenetics o more than 200 conditions.

NHGRI Clinical Studies

www.genome.gov/ClinicalStudies

Learn about clinical studies being conducted by the National Human

Genome Research Institute (NHGRI). Tis online resource lists

eligibility criteria and contact inormation or each study.

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http://www.genome.gov/Health/GARDmailto:[email protected]://www.genome.gov/Health/FactSheetshttp:///reader/full/http://ghr.nlm.nih.govhttp://www.genome.gov/ClinicalStudieshttp://www.genome.gov/Health/GARDmailto:[email protected]://www.genome.gov/Health/FactSheetshttp:///reader/full/http://ghr.nlm.nih.govhttp://www.genome.gov/ClinicalStudies


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Learn moreabout the science of Your Genome

Talking Glossary

www.genome.gov/Education/Glossary

Tis online glossary eatures written denitions, audio explanations

and illustrations. It is designed to help people without scientic

backgrounds understand the terms and concepts used in genetic

research.

Understanding the Human Genome Project

www.genome.gov/Education/Kit

Tis multi-media, educational kit covers the basics o genomic science.

Interactive modules help high-school students to better understand

genetics, molecular biology and the Human Genome Project. It is

available online and as a CD-Rom, which can be requested by sendingan e-mail to [email protected].

Science Fact Sheets

www.genome.gov/Education/FactSheets

NHGRI oers a series o act sheets that explain complex genetic

concepts and research techniques to a non-scientic audience. opics

include cloning, DNA chip technologies and genome-wide association

studies.

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http://www.genome.gov/Education/Glossaryhttp://www.genome.gov/Education/Kitmailto:[email protected]://www.genome.gov/Education/FactSheetshttp://www.genome.gov/Education/Glossaryhttp://www.genome.gov/Education/Kitmailto:[email protected]://www.genome.gov/Education/FactSheets


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