Predictive medicine
Encyclopedia
Predictive medicine is a rapidly emerging field of medicine
Medicine
Medicine is the science and art of healing. It encompasses a variety of health care practices evolved to maintain and restore health by the prevention and treatment of illness....

 that entails predicting disease
Disease
A disease is an abnormal condition affecting the body of an organism. It is often construed to be a medical condition associated with specific symptoms and signs. It may be caused by external factors, such as infectious disease, or it may be caused by internal dysfunctions, such as autoimmune...

 and instituting preventive measures in order to either prevent the disease altogether or significantly decrease its impact upon the patient (such as by preventing mortality
Death
Death is the permanent termination of the biological functions that sustain a living organism. Phenomena which commonly bring about death include old age, predation, malnutrition, disease, and accidents or trauma resulting in terminal injury....

 or limiting morbidity). While different prediction methodologies exist, such as genomics
Genomics
Genomics is a discipline in genetics concerning the study of the genomes of organisms. The field includes intensive efforts to determine the entire DNA sequence of organisms and fine-scale genetic mapping efforts. The field also includes studies of intragenomic phenomena such as heterosis,...

, proteomics
Proteomics
Proteomics is the large-scale study of proteins, particularly their structures and functions. Proteins are vital parts of living organisms, as they are the main components of the physiological metabolic pathways of cells. The term "proteomics" was first coined in 1997 to make an analogy with...

, and cytomics
Cytomics
Cytomics is the study of cell systems at a single cell level. It combines all the bioinformatic knowledge to attempt to understand the molecular architecture and functionality of the cell system...

, the most fundamental way to predict future disease is based on genetics. Although proteomics and cytomics allow for the early detection of disease, much of the time those detect biological markers that exist because a disease process has already started. However, comprehensive genetic testing (such as through the use of DNA arrays or full genome sequencing
Full genome sequencing
Full genome sequencing , also known as whole genome sequencing , complete genome sequencing, or entire genome sequencing, is a laboratory process that determines the complete DNA sequence of an organism's genome at a single time...

) allows for the estimation of disease risk years to decades before any disease even exists, or even whether a healthy fetus
Fetus
A fetus is a developing mammal or other viviparous vertebrate after the embryonic stage and before birth.In humans, the fetal stage of prenatal development starts at the beginning of the 11th week in gestational age, which is the 9th week after fertilization.-Etymology and spelling variations:The...

 is at higher risk for developing a disease in adolescence or adulthood. Individuals who are more susceptible to disease in the future can be offered lifestyle advice or medication with the aim of preventing the predicted illness. Current genetic testing guidelines supported by the health care professionals discourage purely predictive genetic testing of minors until they are competent to understand the relevancy of genetic screening so as to allow them to participate in the decision about whether or not it is appropriate for them. Genetic screening of newborns and children in the field of predictive medicine is deemed appropriate if there is a compelling clinical reason to do so, such as the availability of prevention or treatment as a child that would prevent future disease.

The Goal

The goal of predictive medicine is to predict future disease so that health care professionals and the patient themselves can be proactive in instituting lifestyle modifications and increased physician surveillance, such as bi-annual full body skin exams by a dermatologist or internist if their patient is found to have an increased risk of melanoma
Melanoma
Melanoma is a malignant tumor of melanocytes. Melanocytes are cells that produce the dark pigment, melanin, which is responsible for the color of skin. They predominantly occur in skin, but are also found in other parts of the body, including the bowel and the eye...

 or an EKG and cardiology examination by a cardiologist if a patient is found to be at increased risk for a cardiac arrhythmia. Predictive medicine is intended not for patients but more so for healthy individuals, its purpose being to determine whether susceptibility to a particular disease is increased or not.

A tremendous number of association studies have been published in scientific literature that show associations between specific genetic variants in a person's genetic code and a specific disease. Association and correlation studies have found that a female individual with a mutation
Mutation
In molecular biology and genetics, mutations are changes in a genomic sequence: the DNA sequence of a cell's genome or the DNA or RNA sequence of a virus. They can be defined as sudden and spontaneous changes in the cell. Mutations are caused by radiation, viruses, transposons and mutagenic...

 in the BRCA1
BRCA1
BRCA1 is a human caretaker gene that produces a protein called breast cancer type 1 susceptibility protein, responsible for repairing DNA. The first evidence for the existence of the gene was provided by the King laboratory at UC Berkeley in 1990...

 gene has a 65% cumulative risk of breast cancer. Genetic variants in the Factor V
Factor V
Factor V is a protein of the coagulation system, rarely referred to as proaccelerin or labile factor. In contrast to most other coagulation factors, it is not enzymatically active but functions as a cofactor...

 gene is associated with an increased tendency to form blood clots, such as deep vein thrombosis
Deep vein thrombosis
Deep vein thrombosis is the formation of a blood clot in a deep vein. Deep vein thrombosis commonly affects the leg veins or the deep veins of the pelvis. Occasionally the veins of the arm are affected...

 (DVTs). Genetics tests are expected to reach the market more quickly than new medicines. Myriad Genetics
Myriad Genetics
Myriad Genetics, Inc. is a molecular diagnostic company based in Salt Lake City, Utah. Myriad employs a number of proprietary technologies that permit doctors and patients to understand the genetic basis of human disease and the role that genes play in the onset, progression and treatment of disease...

 is already generating revenue from genetic tests for BRCA1 and BRCA2
BRCA2
BRCA2 is a protein that in humans is encoded by the BRCA2 gene.BRCA2 orthologs have been identified in most mammals for which complete genome data are available....

.

Predictive medicine changes the fundamental paradigm of medicine from being reactive to being proactive and has the potential to significantly decrease the incidence and prevalence of both common and rare diseases.

Examples of Predictive Medicine

Available types of predictive medicine through health care professionals include:
  • Newborn screening
    Newborn screening
    Newborn screening is the process by which infants are screened shortly after birth for a list of disorders that are treatable, but difficult or impossible to detect clinically. Screening programs are often run by state or national governing bodies with the goal of screening all infants born in the...

    : Newborn screening is conducted just after birth to identify genetic disorders that can be treated early in life. This testing of infants for certain disorders is one of the most widespread uses of genetic screening - all US states currently test infants for phenylketonuria
    Phenylketonuria
    Phenylketonuria is an autosomal recessive metabolic genetic disorder characterized by a mutation in the gene for the hepatic enzyme phenylalanine hydroxylase , rendering it nonfunctional. This enzyme is necessary to metabolize the amino acid phenylalanine to the amino acid tyrosine...

     and congenital hypothyroidism
    Hypothyroidism
    Hypothyroidism is a condition in which the thyroid gland does not make enough thyroid hormone.Iodine deficiency is the most common cause of hypothyroidism worldwide but it can be caused by other causes such as several conditions of the thyroid gland or, less commonly, the pituitary gland or...

    . US state law mandates collecting a sample by pricking the heel of a newborn baby to obtain enough blood to fill a few circles on filter paper labeled with names of infant, parent, hospital, and primary physician.
  • Diagnostic testing: Diagnostic testing is conducted to aid in the specificity diagnosis or detection of a disease. It is often used to confirm a particular diagnosis when a certain condition is suspected based on the subject's mutations and physical symptoms. The diversity in diagnostic testing ranges from common consulting room tests such as measuring blood pressure
    Blood pressure
    Blood pressure is the pressure exerted by circulating blood upon the walls of blood vessels, and is one of the principal vital signs. When used without further specification, "blood pressure" usually refers to the arterial pressure of the systemic circulation. During each heartbeat, BP varies...

     and urine tests
    Urinalysis
    A urinalysis , also known as Routine and Microscopy , is an array of tests performed on urine, and one of the most common methods of medical diagnosis...

     to more invasive protocols such as biopsies.
  • Medical bioinformatics: Medical bioinformatics involves determining individual cell molecular parameters by cytomics and single cell-based microarrays. A challenge remains to efficiently extract relevant predictive medicine parameters. This information is frequently extracted by computer-assisted identification and characterization of a few cell populations or gene clusters of interest.
  • Prenatal testing: Prenatal testing is used to look for diseases and conditions in a fetus or embryo
    Embryo
    An embryo is a multicellular diploid eukaryote in its earliest stage of development, from the time of first cell division until birth, hatching, or germination...

     before it is born. This type of testing is offered for couples who have an increased risk of having a baby with a genetic or chromosomal disorder. Screening can determine the sex of the fetus. Prenatal testing can help a couple decide whether to abort
    Abortion
    Abortion is defined as the termination of pregnancy by the removal or expulsion from the uterus of a fetus or embryo prior to viability. An abortion can occur spontaneously, in which case it is usually called a miscarriage, or it can be purposely induced...

     the pregnancy. Like diagnostic testing, prenatal testing can be noninvasive or invasive. Non-invasive techniques include examinations of the woman's womb through ultrasonography or maternal serum screens. These non-invasive techniques can evaluate risk of a condition, but cannot determine with certainty if the fetus has a condition. More invasive prenatal methods are slightly more risky for the fetus and involve needles or probes being inserted into the placenta
    Placenta
    The placenta is an organ that connects the developing fetus to the uterine wall to allow nutrient uptake, waste elimination, and gas exchange via the mother's blood supply. "True" placentas are a defining characteristic of eutherian or "placental" mammals, but are also found in some snakes and...

     or chorionic villus sampling
    Chorionic villus sampling
    Chorionic villus sampling , sometimes misspelled "chorionic villous sampling", is a form of prenatal diagnosis to determine chromosomal or genetic disorders in the fetus. It entails sampling of the chorionic villus and testing it...

    .
  • Carrier testing: Carrier testing is done to identify people who carry one copy of a gene mutation that, when present in both copies, causes a genetic disorder. This type of testing is offered to individuals who have genetic disorder in their family history or to people in ethnic groups with increased risk of certain genetic diseases. If both parents are tested, carrier testing can provide information about a couple's risk of having a child with a genetic disorder.
  • Preconception testing: Preconception testing is conducted on a person or two potential parents before a child is even conceived. This allows prospective parents to understand the risk of diseases and likelihood of traits in their future offspring. Companies have already started to apply preconception testing through sperm banks and egg donation services. A company called Existence Genetics announced in 2010 that it has invented a new patent-pending preconception testing technology that they call the Pythia Approach (it's scientific name is Offspring Projections Through the Combined Analysis of Different Individuals, or OP-CADI) that uses a computer system to combine the genetic makeup of two potential parents in-order to predict the risk of a large number of common and rare diseases, as well as the likelihood of specific traits, in future offspring if those two potential parents were to have a child.

Health Benefits

The future of medicine's focus may potentially shift from treating existing diseases, typically late in their progression, to preventing disease before it sets in. Predictive medicine is based on probabilities: while it evaluates susceptibility to diseases, it is not able to predict with 100% certainty that a specific disease will occur. Unlike many preventive interventions that are directed at groups (e.g., immunization programs), predictive medicine is conducted on an individualized basis. For example, glaucoma
Glaucoma
Glaucoma is an eye disorder in which the optic nerve suffers damage, permanently damaging vision in the affected eye and progressing to complete blindness if untreated. It is often, but not always, associated with increased pressure of the fluid in the eye...

 is a monogenic disease whose early detection can allow to prevent permanent loss of vision. Predictive medicine is expected to be most effective when applied to polygenic multifactorial disease that are prevalent in industrialized countries, such as diabetes mellitus
Diabetes mellitus
Diabetes mellitus, often simply referred to as diabetes, is a group of metabolic diseases in which a person has high blood sugar, either because the body does not produce enough insulin, or because cells do not respond to the insulin that is produced...

, hypertension
Hypertension
Hypertension or high blood pressure is a cardiac chronic medical condition in which the systemic arterial blood pressure is elevated. What that means is that the heart is having to work harder than it should to pump the blood around the body. Blood pressure involves two measurements, systolic and...

, and myocardial infarction
Myocardial infarction
Myocardial infarction or acute myocardial infarction , commonly known as a heart attack, results from the interruption of blood supply to a part of the heart, causing heart cells to die...

. With careful usage, predictive medicine methods such as genetic screens can help diagnose inherited genetic disease caused by problems with a single gene (such as cystic fibrosis
Cystic fibrosis
Cystic fibrosis is a recessive genetic disease affecting most critically the lungs, and also the pancreas, liver, and intestine...

) and help early treatment. Some forms of cancer and heart disease are inherited as single-gene diseases and some people in these high-risk families may also benefit from access to genetic tests. As more and more genes associated with increased susceptibility to certain diseases are reported, predictive medicine becomes more useful.

Direct-to-Consumer Genetic Testing

Direct-to-Consumer (DTC) genetic testing enables a consumer to screen his or her own genes without having to go though a health care professional. They can be ordered without the permission of a physician. Variety in DTC tests range from those testing for mutations associated with cystic fibrosis to breast cancer alleles. DTC tests make the applicability of predictive medicine very real and accessible to consumers. Benefits of DTC testing include this accessibility, privacy of genetic information, and promotion of proactive health care. Risks of obtaining DTC testing are the lack of governmental regulation and the interpreting of genetic information without professional counseling.

Limitations of Predictive Medicine

On a protein
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...

 level, structure is more conserved than sequence. Therefore, in many diseases, having the faulty gene still does not necessarily mean someone will get the disease. Common, complex diseases in the wider population are affected not only by heredity, but also by external causes such as lifestyle and environment. Therefore, genes are not perfect predictors of future health; individuals with both the high risk form of the gene and those without are all candidates to get the disease. Multiple factors in the environment, particular smoking
Smoking
Smoking is a practice in which a substance, most commonly tobacco or cannabis, is burned and the smoke is tasted or inhaled. This is primarily practised as a route of administration for recreational drug use, as combustion releases the active substances in drugs such as nicotine and makes them...

, diet and exercise, infection
Infection
An infection is the colonization of a host organism by parasite species. Infecting parasites seek to use the host's resources to reproduce, often resulting in disease...

, and pollution
Pollution
Pollution is the introduction of contaminants into a natural environment that causes instability, disorder, harm or discomfort to the ecosystem i.e. physical systems or living organisms. Pollution can take the form of chemical substances or energy, such as noise, heat or light...

; play important roles and can be more important than genetic make-up. This makes the results and risks determined by predictive medicine more difficult to quantify. Furthermore, the potential false positives or false negatives that may arise from a predictive genetic screen can cause substantial unnecessary strain on the individual.

Targeting medication to people who are genetically susceptible to a disease but do not yet show the symptoms of it can be a questionable measure. In large populations, there is concern that likely most of the people taking preventative medications would never have developed the disease anyway. Many medications carry undesirable side effects that high risk individuals must then cope with. In contrast, several populations-based prevention measures (such as encouraging healthy diets or banning tobacco advertising) carry a far lower likelihood of adverse effects and are also less expensive.

Another potential downfall of commercially available genetic testing lies within the psychological impacts of accessibility to such data. For single-gene inherited diseases, counseling and the right to refuse a test (the right "not to know") have been found to be important. However, adequate individual counseling can be difficult to employ to the potentially large proportion of the population likely to be identified as at high risk of common complex disease. Some people are vulnerable to adverse psychological reactions to genetic predictions of stigmatized or feared conditions, such as cancer or mental illness.

Ethics and Law

Predictive medicine ushers in a number of sensitive legal and ethical issues. There is a delicate balance that presides over predictive medicine and occupational health: if an employee were dismissed because he was found to be at risk of a certain chemical agent used in his workplace, would his termination be considered discrimination or an act of prevention? Several organizations believe that legislation is needed to prevent insurers and employers from using predictive genetic test results to decide who gets insurance or a job: "Ethical considerations, and legal, are fundamental to the whole issue of genetic testing. The consequences for individuals with regard to insurance and employment are also of the greatest importance, together with the implications for stigma and discrimination." In the future, people may be required to reveal genetic predictions about their health to their employers or insurers. The grim prospect of discrimination based on a person's genetic make-up can lead to a "genetic underclass" which does not receive equal opportunity for insurance and employment.

Currently in the United States, health insurers do not require applicants for coverage to undergo genetic testing. Genetic information is under the same protection of confidentiality as other sensitive health information under the Health Insurance Portability and Accountability Act
Health Insurance Portability and Accountability Act
The Health Insurance Portability and Accountability Act of 1996 was enacted by the U.S. Congress and signed by President Bill Clinton in 1996. It was originally sponsored by Sen. Edward Kennedy and Sen. Nancy Kassebaum . Title I of HIPAA protects health insurance coverage for workers and their...

 (HIPAA) when health insurers come across it. In the United States, the Genetic Information Nondiscrimination Act
Genetic Information Nondiscrimination Act
The Genetic Information Nondiscrimination Act of 2008 , is an Act of Congress in the United States designed to prohibit the improper use of genetic information in health insurance and employment...

, signed into law by President Bush on May 21, 2008; prohibits health insurers from denying coverage or charging differentials in premiums, and bars employers from making job placement or hiring/firing decisions based on individuals' genetic predispositions.

Literature Resources

In 2010, Penguin Publisher's published Outsmart Your Genes, by Brandon Colby, MD
Brandon Colby
Brandon Colby, MD, MBA is an American physician, geneticist, entrepreneur and writer on topics of predictive medicine and genetic testing.He's the author of Outsmart Your Genes and the founder and CEO/Medical Director of Existence Genetics, which is headquartered in Los Angeles, California...

. This book is written for the lay reader and discusses the new field of predictive medicine and genetic testing from the perspective of a physician, and includes a number of pop-culture references such as to Sergei Grinkov
Sergei Grinkov
Sergei Mikhailovich Grinkov was a Russian pair skater. Together with partner Ekaterina Gordeeva, he was the 1988 and 1994 Olympic Champion and four-time World Champion.-Biography:...

, David Bloom
David Bloom
David Bloom was an NBC journalist until his sudden death in 2003 at the age of 39 from deep vein thrombosis...

, and the NFL. In the second half of Outsmart Your Genes
Outsmart Your Genes
In 2010, Penguin published the hardcover book Outsmart Your Genes by Brandon Colby MD. The paperback edition, which contained updated content and a new chapter on on a gene-based cure to HIV infection, was then published in 2011. This book is written for the lay reader and discusses the new field...

, Dr. Colby provides specific examples of how genetic testing can be utilized to lower a person's risk of a large number of diseases, including Alzheimer's, cancer, heart disease, stroke, multiple sclerosis, asthma, and many others.

In 2010, Harper published The Language of Life: DNA and the Revolution in Personalized Medicine, by Francis S. Collins. The book is also written for the lay reader and discusses how genetic testing may be utilized to usher in personalized medicine. Dr. Collins describes general concepts of how genetics may be utilized to combat a large number of diseases, including Alzheimer's and heart disease.

Practitioners of Predictive Medicine

-Brandon Colby, MD
Brandon Colby
Brandon Colby, MD, MBA is an American physician, geneticist, entrepreneur and writer on topics of predictive medicine and genetic testing.He's the author of Outsmart Your Genes and the founder and CEO/Medical Director of Existence Genetics, which is headquartered in Los Angeles, California...

: Existence Health, located in California
-Steven Murphy, MD: The Gene Sherpa, located in Connecticut

See also

  • Newborn screening
    Newborn screening
    Newborn screening is the process by which infants are screened shortly after birth for a list of disorders that are treatable, but difficult or impossible to detect clinically. Screening programs are often run by state or national governing bodies with the goal of screening all infants born in the...

  • Full genome sequencing
    Full genome sequencing
    Full genome sequencing , also known as whole genome sequencing , complete genome sequencing, or entire genome sequencing, is a laboratory process that determines the complete DNA sequence of an organism's genome at a single time...

  • Personalized medicine
    Personalized medicine
    Personalized medicine is a medical model emphasizing in general the customization of healthcare, with all decisions and practices being tailored to individual patients in whatever ways possible...

  • Molecular imaging
    Molecular imaging
    Molecular imaging originated from the field of radiopharmacology due to the need to better understand the fundamental molecular pathways inside organisms in a noninvasive manner.- Overview :...

  • Theranostics
    Theranostics
    Theranostics is the term used to describe the proposed process of diagnostic therapy for individual patients - to test them for possible reaction to taking a new medication and to tailor a treatment for them based on the test results...

  • The Singularity

External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
x
OK