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The availability and the integration of genetic information into our understanding of normal and abnormal growth and development are driving important changes in health care. These changes have fostered the hope that the availability of genetic information will promote a better understanding of disease etiology and permit early, even pre-symptomatic diagnosis and preventive intervention to avoid disease onset. Hence, our aim was to review and provide the insight into the role of genetics in public health and its scope as well as barriers. The use of genetics along with their goals and essential public health functions are discussed. From the era of eugenics to the present era, this area has seen many turns in which geneticists have put through their effort to tie together the strings of both molecular genetics and public health. Though still the dark clouds of eugenics, the predictive power of genes, genetic reductionism, non-modifiable risk factors, individuals or populations, resource allocation, commercial imperative, discrimination and understanding and education are hanging above. The technological and scientific advances that have fundamentally changed our perception of human diseases fuel the expectations for this proactive health.
The mission of health professionals is to “fulfill society’s interest in assuring conditions in which people can be healthy”. This mission requires that we respond to ever-changing priorities and advancements in the scientific world. The past few decades have witnessed major technological advances. Breakthroughs in human genetics provide great promise for improving the health of the public. Genetics has been heralded by some as the new “revolution” in health care,[1–4] suggesting a rapid, fundamental change to, or overthrow of, existing health paradigms. Discoveries in genetics are already impacting society’s health in numerous ways. Every day, health professionals and the general public are provided information about exciting discoveries in areas such as cancer, heart disease, and birth defects, creating expectations for better health services.
Earlier, the science of human genetics was focused on micro-level health influences, and clinical genetics on rare, single gene disorders, providing diagnosis, risk estimation, reproductive options, and some newborn screening. Present studies are clarifying previously unrecognized genetic and phenotypic heterogeneities and attempting to unravel the complex interactions between genes and environment by applying new statistical modeling approaches to twin and family data. Linkage studies using highly polymorphic DNA markers are providing a means of locating candidate genes, including quantitative trait loci (QTL). Apart from the host genome, considerations of the microbial genome have also impacted significantly on clinical practice.
In the decades to come, insights and techniques of molecular genetics will have great influence on prevention and health care. Health care providers should anticipate important new developments rather than just wait and see. For community doctors who can impossibly oversee all relevant developments in sufficient detail, close communication with the community and clinical genetic specialists is necessary to keep pace with the progress. With regard to genetic counseling and reproductive medicine, working agreements between primary care and specialist centers are important. Community-based genetic epidemiology has become a basic science in understanding the human genome. Hence, this review aims to have some insight into the role of genetics in public health and its scope as well as barriers. A bullion search showed 85 related articles in which only 42 relevant articles were consulted. Apart from this, other sources like the book and Google search were obtained.
There has been a historic association between public health and genetics, beginning in the 19th century, when public health and the eugenics movement shared common ground in values and ideas, programs, and personnel. In 1939, high profile geneticists were promoting improvement of the genetic constitution of the population through voluntary eugenics, facilitated by changing social conditions and human attitudes. Simultaneously, public health was focused on preventing disease primarily through the control of infection and malnutrition. There was an unspoken collaboration in place whereby public health could continue to prevent the deaths of the unfit so long as eugenics prevented the unfit from passing on their defects, thus counteracting “degeneration” of the population. In the 1940s, many people, including those who were involved with public health, withdrew their support for eugenics, as the ethics behind these practices were increasingly questioned. By the 1950s, human genetics had disentangled itself from eugenics and the practice of non-directive genetic counseling was introduced. This divergence was maintained throughout the second half of the 20th century with public health shifting focus from infectious diseases to complex, chronic diseases and geneticists concentrated on mapping the human genome. Effective presentation of well-researched science and expression of realistic views should facilitate a more comfortable convergence in time.[7–14]
Clinical epidemiological methodology can contribute a lot to the quality of molecular clinico-genetic studies. Long-term follow-up to evaluate predictions and interventions needs more attention and can easily be integrated into primary care medicine. Primary health care providers, motivated to learn complex materials and new skills in order to assist their patient’s genetics, can do so in a relatively short time period.
Professor Leo ten Kate rejects the term “public health genetics”, and proposes to use “community genetics” instead, because the latter refers to values that are not safe with the first. The term “public health genetics” has been introduced to denote the interface between genetics and public health, and is used in titles of training courses and names of research groups. It reflects attempts of the public health profession to cope with, and make best use of, the rapid advances in genetics. Genetic tests can, for example, be used in screening programs for disease or for targeting health promotion interventions. “Community genetics”, on the other hand, reflects attempts of clinical geneticists to apply their counseling methods to the whole population. According to ten Kate, clinical genetics embodies a non-directive approach that is badly needed when genetics is applied at a population-wide level. The public health approach is seen to be too directive, and to have an undue focus on achieving health gains for the population as a whole, instead of helping individuals to make autonomous choices, for example, when it comes to the reproductive options that they face when presented with genetic information.
It is evident that genetics will become a fundamental component of the policy and practice roles of public health agencies by 2010,[17,18] making careful consideration of the framework and process for meeting this essential challenge. A larger challenge for state and local public health officials is setting standards for the role of genetics within the broad scope of core public health functions. Public health officials may be expected to provide criteria for 1) using genetic tests to predict the probability of disease and impact of interventions; 2) using genetic screening and services throughout the life span; and 3) preventing inappropriate uses of genetic testing.
The three core public health functions and genetics are discussed below.
To improve health, it is important to understand how genetics interacts with other factors. Therefore, it is necessary to regularly collect, analyze, and share information, including genetic information and environmental interactions related to health conditions, risks, and community resources. The surveillance is needed to determine:
Establishing criteria for genetic testing recommendations may involve reassessing data using additional vital statistics or other factors. Other factors include the availability of quality genetic resources in the community, the appropriateness of genetic technologies offered to the community, the accessibility of clinical and genetic services, the costs and benefits of using genetic technology, and the community’s knowledge of the use of genetics to improve health. This information is necessary for state health officials and others responsible for providing health policy guidance, to enact policies and programs that are best for their communities.
Public health policies also provide members of the public with objective guidance and information to empower them in decision making regarding the use of genetic technologies. Issues such as health insurance discrimination, population screening, and privacy and confidentiality require guidance from State Health Officials to ensure the public’s health and minimize potential harm.
Agencies may collaborate with other public and private entities and educate public health staff and private health-care workers about the use of genetic information to improve health. Programmatically, the incorporation of up-to-date genetic information in areas such as maternal and child health, occupational health, and disease prevention programs will improve outcomes by providing better prevention information. This information should be available in formats that are appropriate to the target audience in terms of reading level and cultural competence. Enhancement of data systems to include genetic information, with appropriate privacy protections, can be part of ongoing considerations for program improvement. Outcome evaluations that include genetic information will create an opportunity to develop more effective policies and practices. Some health agencies may find it necessary to assure the availability and quality of laboratory and clinical genetic services in their state through licensing and certification activities.
The development and maintenance of a strong health data collection system with the capacity to monitor genetic factors that affect health status and identify health problems is one of the essential public health services. Data collected in these systems could include genetic variants, health status, demographics, interventions, environmental triggers, and safety and efficacy of genetic technologies. They provide new insights into prevention.
Applied public health research into the causes of health problems, including relevant genetic factors, is the key to understand how diseases can be prevented and to reduce their burden in the community.
There are many barriers to effective convergence and approach to prevention and management of complex diseases from a multidisciplinary perspective. They are as follows.
The main objective for using genetic information in public health today is not to enhance, change, or remove one’s genes, but to promote their optimal expression. Neither the possibility of a new eugenics era nor the changes in social values and economic influences can be ruled out.
Not all genetic variants found to be associated with disease are clinically useful. Genetic tests should be introduced only when the predictive power is established within particular populations, and with knowledge of the “number needed to screen” (analogous to the “number needed to treat” concept) to prevent one case of disease Cost-benefit analyses and rigorous evaluation of genetic screening programs is essential.
Some public health professionals are concerned that at a time when there are moves to address inequalities in socioeconomic and political factors affecting health identification of genetic risk might move us back toward the “single cause for single disease” paradigm (analogous to the “germ theory” of the 19th–20th century). A reductionist approach can be useful for identifying genetic associations with disease and elucidating etiological pathways in a research setting, but does not reflect the way genes operate in complex biological systems.
The term “individualistic fallacy” has been used to describe the situation where the major population determinants of health are ignored and the focus is on individual level variables – a criticism of genetic as well as other individual risk factor epidemiology. The challenge that has been presented to epidemiologists is to embrace multiple levels of risk, from the molecular to the population and societal level, and new statistical techniques are being designed to integrate these levels of risk.
Public health evolved on the premise that genes could not be modified, effectively disqualifying them as targets for intervention. However, for complex diseases, genetic information may be used either pre-symptomatically or after the disease onset, for targeted interventions including diet, medication, and lifestyle modifications. Genetic information may motivate people to improve their health behavior, or, at the other extreme, it may lead to a fatalistic view of genetic risk with people shunning preventive behaviors or treatments. The use of genetic information to improve risk identification may emphasize the high risk approach to public health.
Public health, which seeks to improve the health of populations, has to recognize the importance of the individual. These changes offer challenges to public health practitioners and epidemiologists to encompass the individual view while maintaining efforts to promote the health of populations through a collective approach. This may be facilitated via informed consent and also the provision to opt out of public health programs, such as the one now in place for newborn screening.
Imbalance in distribution of public resources in health care has been the cry of every public health professional. A major area of concern is the prioritization of competitive research funding in favor of genetics. Another area of concern is the predicted investment in health services required for new genetic technologies and tests. A symposium on community genetics in developing countries was held in India in 2002. An estimated half million babies are born every year in India with a birth defect, and birth defects have overtaken infection as a cause of perinatal mortality. Therefore, government support of existing, integrated local and district health centers and practitioners has been strongly advocated. The symposium discussed the establishment of community-controlled prenatal and newborn screening programs, hand in hand with education and awareness campaigns. To seriously impact on health in developing countries through genomics, a global approach with “innovative financing mechanisms” is required.
Commercial laboratories may bypass recommended pre-test genetic counseling when offering “over the counter” genetic testing. There are over 100 websites worldwide offering genetic testing for a variety of purposes, for example, parentage, identity, forensic, immigration, health-related genetic tests, and DNA banking. Significantly, 12 commercial organizations have been identified that offer adult genetic susceptibility testing. Any promotion of this type of testing will have ramifications for the public purse because of the increased need for follow-up health services. It may also exacerbate inequalities in access and there are concerns about privacy, safety, and quality. It is unclear how often patents for gene sequences related to susceptibility genes for complex conditions will be granted and then enforced, but they potentially have much greater public health implications.
Genetically susceptible population subgroups may be identified, marginalized, or discriminated against in various ways – the creation of a “genetic underclass”. Family relationships, insurance (life, travel, and health), employment, finance, adoption, migration, forensic, and legal settings (paternity testing) are all examples of where genetic discrimination may occur. In reality, there have not been widespread cases of genetic discrimination yet, but possibilities do exist. After many years of negotiation, the US Senate passed the Genetic Information Nondiscrimination Act of 2003 and it now remains to be seen if the House of Representatives will pass it. This bill would prevent health insurers and employers from using genetic information to determine eligibility, set premiums, or hire and fire people.
The complexity of genetics dictates the need for specialized languages and bodies of information. Genetic literacy assumes that the average person can evaluate the credibility of information that has implications for personal and public health, but most do not have this skill. Multidisciplinary education programs for health professionals are needed on the scientific, ethical, legal, and social issues related to public health genetics, as are programs on bioinformatics and statistical genetics, cultural anthropology, and health behavior.
A greater use of family history information to stratify individuals into average, moderate, and high risk for common diseases has been proposed, to guide prevention strategies. Those who are already identified as high risk based on family history are benefiting from predictive testing for single gene disorders (for example, some cancers), with those at moderate risk next in line. In time, testing might be broadened to those at average risk of common complex disorders. There is an urgent need for the integration of genetic screening into the public health services in India.
It will take time but will clarify uncertainties and most importantly affirm that research and development in genetics need not diminish the importance of social and environmental determinants of health, and can in fact render the interventions more effective than before. The Massachusetts Department of Public Health (MDPH) has identified the following areas of focus for statewide public health genetics initiatives (2003–2005).
The first international conference on community genetics, which was held in Canada in June 2000 (Jonquière, Québec), offered the opportunity for common reflection and discussion on a definition of community genetics. The real challenge now facing genetics is how to devise and deliver appropriate services so that individuals, families, and communities are sufficiently empowered and supported to make informed decisions about their genetic health. Community-based genetic counseling and education are the central components of the infrastructure that would deliver those services.
In view of the current developments, community practitioners must integrate community genetics into their daily routine and critically anticipate possibly relevant innovations. The convergence of public health and genetics holds the possibility of improved understanding of the etiology, prevention, and management of complex diseases such as diabetes, dementia, heart disease, cancer including oral cancers, dental diseases, and syndromes.
Source of Support: Nil
Conflict of Interest: None declared.