Predictive medicine

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Predictive medicine is a field of medicine that entails predicting the probability of disease 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 or limiting morbidity). [1]

Contents

While different prediction methodologies exist, such as genomics, proteomics, and cytomics, 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) allows for the estimation of disease risk years to decades before any disease even exists, or even whether a healthy fetus 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. [2] 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 the probability of 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, an EKG and cardiology examination by a cardiologist if a patient is found to be at increased risk for a cardiac arrhythmia or alternating MRIs or mammograms every six months if a patient is found to be at increased risk for breast cancer. Predictive medicine is intended for both healthy individuals ("predictive health") and for those with diseases ("predictive medicine"), its purpose being to predict susceptibility to a particular disease and to predict progression and treatment response for a given disease.

A 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 in the BRCA1 gene has a 65% cumulative risk of breast cancer. [3] Additionally, new tests from Genetic Technologies LTD and Phenogen Sciences Inc. comparing non-coding DNA to a woman's lifetime exposure to estrogen can now determine a woman's probability of developing estrogen positive breast cancer also known as sporadic breast cancer (the most prevalent form of breast cancer). Genetic variants in the Factor V gene is associated with an increased tendency to form blood clots, such as deep vein thrombosis (DVTs). [4] Genetics tests are expected to reach the market more quickly than new medicines. Myriad Genetics is already generating revenue from genetic tests for BRCA1 and BRCA2. [5]

Aside from genetic testing, predictive medicine utilizes a wide variety of tools to predict health and disease, including assessments of exercise, nutrition, spirituality, quality of life, and so on. This integrative approach was adopted when Emory University and Georgia Institute of Technology partnered to launch the Predictive Health Institute. [6] Predictive medicine changes the paradigm of medicine from being reactive to being proactive and has the potential to significantly extend the duration of health and to decrease the incidence, prevalence and cost of diseases.

Types

Notable types of predictive medicine through health care professionals include:

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 health and 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 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, hypertension, and myocardial infarction. 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) and help early treatment. [7] 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 through 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 level, structure is less conserved than sequence. Therefore, in many diseases, having the faulty gene still does not necessarily mean someone will get the disease. [8] 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, diet and exercise, infection, and pollution; play important roles and can be more important than genetic make-up. [9] 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. [10] 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. [11] 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." [12] 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. [13]

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 (HIPAA) when health insurers come across it.

See also

Related Research Articles

<span class="mw-page-title-main">Genetic disorder</span> Health problem caused by one or more abnormalities in the genome

A genetic disorder is a health problem caused by one or more abnormalities in the genome. It can be caused by a mutation in a single gene (monogenic) or multiple genes (polygenic) or by a chromosomal abnormality. Although polygenic disorders are the most common, the term is mostly used when discussing disorders with a single genetic cause, either in a gene or chromosome. The mutation responsible can occur spontaneously before embryonic development, or it can be inherited from two parents who are carriers of a faulty gene or from a parent with the disorder. When the genetic disorder is inherited from one or both parents, it is also classified as a hereditary disease. Some disorders are caused by a mutation on the X chromosome and have X-linked inheritance. Very few disorders are inherited on the Y chromosome or mitochondrial DNA.

Penetrance in genetics is the proportion of individuals carrying a particular variant of a gene that also expresses an associated trait. In medical genetics, the penetrance of a disease-causing mutation is the proportion of individuals with the mutation that exhibit clinical symptoms among all individuals with such mutation. For example, if a mutation in the gene responsible for a particular autosomal dominant disorder has 95% penetrance, then 95% of those with the mutation will develop the disease, while 5% will not.

Genetic counseling is the process of investigating individuals and families affected by or at risk of genetic disorders to help them understand and adapt to the medical, psychological and familial implications of genetic contributions to disease. This field is considered necessary for the implementation of genomic medicine. The process integrates:

<span class="mw-page-title-main">Genetic testing</span> Medical test

Genetic testing, also known as DNA testing, is used to identify changes in DNA sequence or chromosome structure. Genetic testing can also include measuring the results of genetic changes, such as RNA analysis as an output of gene expression, or through biochemical analysis to measure specific protein output. In a medical setting, genetic testing can be used to diagnose or rule out suspected genetic disorders, predict risks for specific conditions, or gain information that can be used to customize medical treatments based on an individual's genetic makeup. Genetic testing can also be used to determine biological relatives, such as a child's biological parentage through DNA paternity testing, or be used to broadly predict an individual's ancestry. Genetic testing of plants and animals can be used for similar reasons as in humans, to gain information used for selective breeding, or for efforts to boost genetic diversity in endangered populations.

<span class="mw-page-title-main">Prenatal testing</span> Testing for diseases or conditions in a fetus

According to the CDC, birth defects occur in approximately 3% of births in the United States every year. Prenatal testing is a tool that can be used to detect some of these abnormalities at various stages prior to birth. Prenatal testing consists of prenatal screening and prenatal diagnosis, which are aspects of prenatal care that focus on detecting problems with the pregnancy as early as possible. These may be anatomic and physiologic problems with the health of the zygote, embryo, or fetus, either before gestation even starts or as early in gestation as practicable. Screening can detect problems such as neural tube defects, chromosome abnormalities, and gene mutations that would lead to genetic disorders and birth defects, such as spina bifida, cleft palate, Down syndrome, Tay–Sachs disease, sickle cell anemia, thalassemia, cystic fibrosis, muscular dystrophy, and fragile X syndrome. Some tests are designed to discover problems which primarily affect the health of the mother, such as PAPP-A to detect pre-eclampsia or glucose tolerance tests to diagnose gestational diabetes. Screening can also detect anatomical defects such as hydrocephalus, anencephaly, heart defects, and amniotic band syndrome.

<span class="mw-page-title-main">Personalized medicine</span> Medical model that tailors medical practices to the individual patient

Personalized medicine, also referred to as precision medicine, is a medical model that separates people into different groups—with medical decisions, practices, interventions and/or products being tailored to the individual patient based on their predicted response or risk of disease. The terms personalized medicine, precision medicine, stratified medicine and P4 medicine are used interchangeably to describe this concept though some authors and organisations use these expressions separately to indicate particular nuances.

<span class="mw-page-title-main">Medical genetics</span> Medicine focused on hereditary disorders

Medical genetics is the branch of medicine that involves the diagnosis and management of hereditary disorders. Medical genetics differs from human genetics in that human genetics is a field of scientific research that may or may not apply to medicine, while medical genetics refers to the application of genetics to medical care. For example, research on the causes and inheritance of genetic disorders would be considered within both human genetics and medical genetics, while the diagnosis, management, and counselling people with genetic disorders would be considered part of medical genetics.

<span class="mw-page-title-main">Myriad Genetics</span> American biotechnology company

Myriad Genetics, Inc. is an American genetic testing and precision medicine company based in Salt Lake City, Utah, United States. 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. This information is used to guide the development of new products that assess an individual's risk for developing disease later in life, identify a patient's likelihood of responding to a particular drug therapy, assess a patient's risk of disease progression and disease recurrence, and measure disease activity.

<span class="mw-page-title-main">Roxana Moslehi</span> Genetic epidemiologist

Roxana Moslehi is an Iranian-born genetic epidemiologist.

Public health genomics is the use of genomics information to benefit public health. This is visualized as more effective preventive care and disease treatments with better specificity, tailored to the genetic makeup of each patient. According to the Centers for Disease Control and Prevention (U.S.), Public Health genomics is an emerging field of study that assesses the impact of genes and their interaction with behavior, diet and the environment on the population's health.

<span class="mw-page-title-main">Hereditary breast–ovarian cancer syndrome</span> Medical condition

Hereditary breast–ovarian cancer syndromes (HBOC) are cancer syndromes that produce higher than normal levels of breast cancer, ovarian cancer and additional cancers in genetically related families. It accounts for 90% of the hereditary cancers. The hereditary factors may be proven or suspected to cause the pattern of breast and ovarian cancer occurrences in the family. The name HBOC may be misleading because it implies that this genetic susceptibility to cancer is mainly in women. In reality, both sexes have the same rates of gene mutations and HBOC can predispose to other cancers including prostate cancer and pancreatic cancer. For this reason, the term "King syndrome" has recently come into use. The new name references Mary-Claire King who identified the genes BRCA1 and BRCA2.

Joseph Daniel Schulman is a physician, medical researcher, and biomedical entrepreneur in the fields of genetic diseases and human reproduction.

<i>BRCA</i> mutation Medical condition

A BRCA mutation is a mutation in either of the BRCA1 and BRCA2 genes, which are tumour suppressor genes. Hundreds of different types of mutations in these genes have been identified, some of which have been determined to be harmful, while others have no proven impact. Harmful mutations in these genes may produce a hereditary breast–ovarian cancer syndrome in affected persons. Only 5–10% of breast cancer cases in women are attributed to BRCA1 and BRCA2 mutations, but the impact on women with the gene mutation is more profound. Women with harmful mutations in either BRCA1 or BRCA2 have a risk of breast cancer that is about five times the normal risk, and a risk of ovarian cancer that is about ten to thirty times normal. The risk of breast and ovarian cancer is higher for women with a high-risk BRCA1 mutation than with a BRCA2 mutation. Having a high-risk mutation does not guarantee that the woman will develop any type of cancer, or imply that any cancer that appears was actually caused by the mutation, rather than some other factor.

For preventing Tay–Sachs disease, three main approaches have been used to prevent or reduce the incidence of Tay–Sachs disease in those who are at high risk:

<span class="mw-page-title-main">Hereditary cancer syndrome</span> Inherited genetic condition that predisposes a person to cancer

A hereditary cancer syndrome is a genetic disorder in which inherited genetic mutations in one or more genes predispose the affected individuals to the development of cancer and may also cause early onset of these cancers. Hereditary cancer syndromes often show not only a high lifetime risk of developing cancer, but also the development of multiple independent primary tumors.

<span class="mw-page-title-main">Molecular diagnostics</span> Collection of techniques used to analyze biological markers in the genome and proteome

Molecular diagnostics is a collection of techniques used to analyze biological markers in the genome and proteome, and how their cells express their genes as proteins, applying molecular biology to medical testing. In medicine the technique is used to diagnose and monitor disease, detect risk, and decide which therapies will work best for individual patients, and in agricultural biosecurity similarly to monitor crop- and livestock disease, estimate risk, and decide what quarantine measures must be taken.

A variant of uncertainsignificance (VUS) is a genetic variant that has been identified through genetic testing but whose significance to the function or health of an organism is not known. Two related terms are "gene of uncertain significance" (GUS), which refers to a gene that has been identified through genome sequencing but whose connection to a human disease has not been established, and "insignificant mutation", referring to a gene variant that has no impact on the health or function of an organism. The term "variant' is favored in clinical practice over "mutation" because it can be used to describe an allele more precisely. When the variant has no impact on health, it is called a "benign variant". When it is associated with a disease, it is called a "pathogenic variant". A "pharmacogenomic variant" has an effect only when an individual takes a particular drug and therefore is neither benign nor pathogenic.

<span class="mw-page-title-main">L1 syndrome</span> Medical condition

L1 syndrome is a group of mild to severe X-linked recessive disorders that share a common genetic basis. The spectrum of L1 syndrome disorders includes X-linked complicated corpus callosum dysgenesis, spastic paraplegia 1, MASA syndrome, and X-linked hydrocephalus with stenosis of the aqueduct of Sylvius (HSAS). It is also called L1CAM syndrome and CRASH syndrome, an acronym for its primary clinical features: corpus callosum hypoplasia, retardation, adducted thumbs, spasticity, and hydrocephalus.

Wendy K. Chung is an American clinical and molecular geneticist and physician. She currently directs the clinical genetics program at NewYork–Presbyterian Hospital / Columbia University Medical Center in New York City and serves as the Kennedy Family Professor of Pediatrics. She is the author of 600 peer-reviewed articles and 75 chapters and has won several awards as a physician, researcher, and professor. Chung helped to initiate a new form of newborn screening for spinal muscular atrophy which is used nationally and was among the plaintiffs in the Supreme Court case which banned gene patenting.

Elective genetic and genomic testing are DNA tests performed for an individual who does not have an indication for testing. An elective genetic test analyzes selected sites in the human genome while an elective genomic test analyzes the entire human genome. Some elective genetic and genomic tests require a physician to order the test to ensure that individuals understand the risks and benefits of testing as well as the results. Other DNA-based tests, such as a genealogical DNA test do not require a physician's order. Elective testing is generally not paid for by health insurance companies. With the advent of personalized medicine, also called precision medicine, an increasing number of individuals are undertaking elective genetic and genomic testing.

References

Citations

  1. ↑ "Predictive medicine: Genes indicate diseases before symptoms do". Archived from the original on 2010-12-27. Retrieved 2009-02-24.
  2. ↑ Borry P; Evers-Kiebooms G; Cornel MC; Clarke A; et al. (June 2009). "Genetic testing in asymptomatic minors: background considerations towards ESHG Recommendations". Eur. J. Hum. Genet. 17 (6): 711–9. doi:10.1038/ejhg.2009.25. PMC   2947094 . PMID   19277061.
  3. ↑ Antoniou A; Pharoah PD; Narod S; et al. (May 2003). "Average risks of breast and ovarian cancer associated with BRCA1 or BRCA2 mutations detected in case Series unselected for family history: a combined analysis of 22 studies". Am. J. Hum. Genet. 72 (5): 1117–30. doi:10.1086/375033. PMC   1180265 . PMID   12677558.
  4. ↑ "Recurrent episodes of deep vein thrombosis in a young man | DocGuide".
  5. ↑ "BRCA Gene Mutations: Cancer Risk and Genetic Testing Fact Sheet - National Cancer Institute". 25 November 2020.
  6. ↑ "Emory-Georgia Tech Predictive Health Institute".
  7. ↑ "Genetics and 'Predictive Medicine': Selling Pills, Ignoring Causes". 23 January 2003.
  8. ↑ Vineis P; Schulte P; McMichael AJ (March 2001). "Misconceptions about the use of genetic tests in populations". Lancet. 357 (9257): 709–12. doi:10.1016/S0140-6736(00)04136-2. PMID   11247571. S2CID   34364675.
  9. ↑ Baird P (2001). "The Human Genome Project, genetics and health". Community Genet. 4 (2): 77–80. doi:10.1159/000051161. PMID   12751482. S2CID   13399004.
  10. ↑ Marteau TM; Lerman C (April 2001). "Genetic risk and behavioural change". BMJ. 322 (7293): 1056–9. doi:10.1136/bmj.322.7293.1056. PMC   1120191 . PMID   11325776.
  11. ↑ Dausset J (March 1997). "[Predictive medicine and its ethics]". Pathol. Biol. (in French). 45 (3): 199–204. PMID   9296063.
  12. ↑ GeneWatch UK (2001), Genetic Testing in Insurance and Employment: A New Form of Discrimination. Briefing 15, June 2001.
  13. ↑ Schulte PA; Lomax GP; Ward EM; Colligan MJ (August 1999). "Ethical issues in the use of genetic markers in occupational epidemiologic research". J. Occup. Environ. Med. 41 (8): 639–46. doi:10.1097/00043764-199908000-00005. PMID   10457506.

Sources

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