Human Genetic Screening

Malay Chandan Saha

Copyright 1998


Genetics provide powerful knowledge that is changing humanity’s view of itself and its relation to rest of the universe. Genetic, cytogenetic and molecular genetic studies showed the relatedness of human being to other living things on the planet, including plants, fungi and bacterium (4). Little change in DNA contributes to human variations. So, genomic variations of human species are being studied through DNA analysis from populations, families, and individuals worldwide.

Human Genome Project (HGP) was proposed in the 1980s and was formally initiated in 1990. Its specific goals are to map and determine the chemical sequences of the three billion nucleotide base pairs that comprise the human genome. Completion of the HGP in the projected 15 years will provide a source book for biology and medicine (5). The Human Genome Diversity Project (HGDP) complements the HGP by examining the genomic variation of the human species, through analysis of DNA from populations, families and individuals worldwide. This will help us to understand the fundamental unity of humankind, human biological history, population movements, and susceptibility to resistance to various human diseases. HGDP ran into heavy fire on ethical grounds and fears that it might violate indigenous people’s rights, however, and it remains stalled for lack of funds (7).

A large proportion of human health has a genetic basis. Abnormal forms of a single or a group of genes that are passed from generation to generation causes inherited genetic diseases. Diseases like Alzheimer’s, familial breast cancer, cystic fibrosis are inherited as single gene and are characterized at molecular level (4). Many genes along with environmental interactions control diseases like hypertension, diabetes, and various forms of cancer and infections. These diseases are also being investigated using molecular approach. So, genomic information on human sp. will be a valuable tool to judge an individual, a family or a population, which ultimately help to genetic screening.

Genetic Screening

The national Academy of Sciences (NAS) defines genetic screening as the systematic search of populations for persons with latent, early, or a symptomatic disease. Some of the literature annotated for this Scope Note appears to use the terms ‘screening’ and ‘genetic testing’ interchangeable. Genetic screening, the systematic search for persons with a particular genotype in a defined population serves as an important adjunct of modern preventive medicine. Such screening has the potential to lessen the devastating impact of genetic disease. The usual purpose is to identify persons whose genotype places them or their offspring at risk for a genetic disease (9).

According to NAS, genetic screening can be used for medical intervention and research, for reproductive information, for enumeration, monitoring and surveillance, and for registries of genetic disease and disability. There are two classes of genetic screening- I) the detection of persons whose own health is threatened i.e. presymptomatic screening and ii) the detection of those healthy individuals whose genes threaten the health of their future offspring i.e. carrier screening. However, genetic screening usually include parental screening, newborn screening, carrier screening, forensic screening and susceptibility screening (8).

Parental screening discerns whether a fetus is at risk for various identifiable genetic diseases or traits. Parental screening began in 1966. Since then the number of metabolic defects and genetic disorders that can be diagnosed prenatally has expanded greatly. Preimplantation testing of embryos might ensure that those only embryos free of genetic disease or problem traits would be placed in the uterus.

Newborn screening involves the analysis of blood or tissue samples taken in early infancy in order to detect genetic diseases for which early intervention can avert serious health problems or death. Newborn screening first came into use in the early 1960s with the ability to test newborns for a rare metabolic disease, phenylketonuria (PKU). Two other examples of newborn screening are the testing of African American infants for sickle cell anemia and Ashkenazic Jews for Tay-Sachs disease. Requirements for this type of genetic screening are that it is economical, logistically possible, and reliable for the diagnosis of disease early enough to initiate a therapy that will prevent permanent and irreversible damage, even death (9).

Carrier screening identifies individuals with a gene or a chromosome abnormality that may cause problems either for offspring or the person screened. The testing of blood or tissue samples can indicate the existence of a particular genetic trait, changes in chromosomes, or changes in DNA that are associated with inherited diseases in asymptomatic individuals. Examples of carrier screening include sickle cell anemia and for Tay-Sachs disease. In last few years, screening tests have also been developed for cystic fibrosis, Duchenne muscular dystrophy, hemophilia, Huntington’s disease, and neurofibromatosis. Screening the susceptible population for Tay-Sachs has significantly lowered the number of newborns affected by this lethal disease in the United States.

Forensic screening seeks to discover a genetic linkage between suspects and evidence discovered in criminal investigations. Screening technologies accurately detect genetic differences between humans and are ‘new, powerful tools to clear the innocent and convict the guilty". Since DNA is unique, many people are reluctant to see such information become part of any national database, which might include information not only about identity but also about proclivity toward disease or behavior.

Susceptibility screening involves the screening of selected populations for genetic susceptibility to environmental hazards. This screening is used to identify workers who may be susceptible to toxic substances that are found in their workplace and may cause future disabilities. In 1986, Morton Hunt wrote in the New York Times Magazine that 390,000 workers become disabled by occupational illness each year; he thinks these illnesses are precipitated by genetic hypersusceptibility since co-workers are unaffected (8). The most common type of screening in the practice of a medical geneticist is family screening. Not infrequently, the pedigree analysis will identify others in the families who are ignorant of their potential risk.

Factors affecting the use of any routine screening:

Genetic Screening Controversy

Information obtained from genetic testing end genetic screening raises ethical and legal questions about its uses by society. Sensitivity to the needs of the groups screened and the inclusion of those groups in the planning of screening programs can frame the diagnosis and understanding of genetic disease with respect to issues of race, ethnicity, and gender. Patients, physicians, and genetic counselors must understand what these tests actually predict or diagnose in order to ensure that patients make fully informed autonomous decisions about the test results (6).

The Committee of Ministers of the Council of Europe thinks that the public generally recognizes the benefits and the potential usefulness of genetic testing. Screening for individuals, for families, and for the population as a whole, but it says that there is an accompanying anxiety that genetic testing and screening arouses. The Danish Council of Ethics views genetic information as different from other private information since it reveals knowledge not only about an individual, but also the individual’s relatives. Thus the screening provides information useful either to the individual or to public health officials, but this information is not concerned with treatment. From a public health point of view, testing may prevent costly treatment of a disease, protect third parties, and give the person the option of treatment. However, from the individual’s point of view, there may be ambivalence about the possibility of a relative’s potential disease (8).

The potential problem raised both by those who favor testing and screening and those who oppose it are similar, but one faction thinks that regulatory or legislative solutions to the problems can be found while concerned opponents find the knowledge itself less valuable and the problems unsolvable. Opponents of widespread genetic testing and screening regard the acceptance of eugenic theories and scientists inability to control outcomes of their genetic research as dangerous. They foresee a need to outlaw technologies that threaten privacy or civil rights and a need to protect against genetic discrimination. Lowe (1991) points out that genetic testing will not create more illness than presently exists, and it could lead to a reduction in costs due to early treatment. Lippman (1992) suggested that control over genetics would create an elite who could control the general populace, particularly if mandatory testing or intervention were viewed as a community good. Other potential adverse effects of such screening include the development of prejudice against those tested and found at risk and the feeling of tested persons that they are predetermined victims of fate or are being branded as ‘abnormal’.

Fletcher and Wertz have surveyed geneticists throughout the world. They stated that ‘the dangers of isolation, loss of insurance, educational, and job opportunities for persons diagnosed with incurable and costly disorders known from early childhood are real to many who are concerned about potential clinical uses and abuses of the new genetics.’

According to the Privacy Commission of Canada, genetic privacy has two dimensions: protection from the intrusions of others and protection from one’s own secrets. It concludes that privacy is an explicit constitutional right that includes respect for genetic privacy and is protected by legislation. So, general population screening, even in the Ashkenazi community, is not considered desirable or appropriate. Any program or research project must have ethical approval. No screening within family’s should be undertaken without full and proper consideration of the effects of any potential result. Counseling must be available prior to any screening (2).

In nationwide survey, 80% of the public indicates that it expects genetic technology to be beneficial, 71% thought that it would pose risks to them and their family, and 62% thought the benefits outweighed the risks. Louis Harris poll in 1992 found that 68% of the persons questioned knew little or nothing about genetic testing, but 79% would undergo testing prior to having children to learn whether a child might inherit a fatal genetic disease. Strict regulations are favored by 75% of those polled.

In any genetic screening, guidelines should be established governing its aim, limitations, scope, and ethical aspects, as well as the storage and registration of data or material, the need for follow-up (including social consequences), and the risk of side effects. Genetic screening should always be voluntary, not mandatory, according to 99% of those surveyed by the OTA with reference to cystic fibrosis screening.

The U.S. Department of Energy (DOE) and the National Institutes of Health (NIH) have devoted 3% to 5% of their annual Human Genome Program budgets toward studying the ethical, legal, and social issues surrounding availability of genetic information. Some ethical, legal, and social issues (ELSI) raised by the increased availability of genetic information are (1):


As the time progresses, knowledge on genetic of human genome advances. Collaborative effort have been made by many countries to get complete human genetic sequence. As a consequence genetic screening is also progressing to measure the diversity of human species. The benefits are being seen principally in medical area. Many diseases like Alzheimer disease, familial breast cancer, cystic fibrosis etc. can be detected at an early stage. Early detection opens the door for early treatment.

On the contrary, a series of ethical and social dilemmas are arising due to genetic screening. Any genetic disorder of a fetus clearly can influence abortion, which is a broadly discussed issue for different religion. Genetic screening will also be used for discrimination against by health insurance and employers. To ensure the benefits of genetic screening the pitfalls should be eliminated. Genetic screening guidelines should be established governing its aim, limitations, scope and ethical aspects of a particular population. Data storage and registration should be protected properly. Progressive development has been achieved in this respect. The President’s Commission recommended that information stored in computers should be coded and that compulsory genetic screening cannot be justified to create a health gene pool or to reduce health costs. Recently US Senate approved unanimously a health reform bill that explicitly bars insurers from using genetic information to deny coverage of applicants, which will protect people from losing health insurance. Rightly or wrongly, many people are now convinced that genes are special, that they contain and reveal a person’s, or a people’s, essence, which has enormous value, spiritual and commercial. This exaggerated emphasis on the importance of individual genetic variation makes human genomic research particularly sensitive (1).

Genetic screening has been bringing much useful information for human being, on the other hand creates many controversy. Though it is difficult but not impossible to solve those controversies. We cannot ignore the benefits of genetic screening. Personally I am in favor of it and I do believe that by protecting the human rights and privacy through legislation the benefits of genetic screening can be effectively applied for human welfare.


1. Ethical, Legal, and Social Issues (ELSI). Obtained from WWW. 11/02/98.

2. Genetic screening and Counseling. Obtained from WWW. 11/03/98.

3. Greely, Henry T. 1998. Genomic Research and human Subjects. Science. 282(5389): p 625.

4. Griffiths, An introduction to Genetic Analysis.

5. Human Genome Project Information. Obtained from WWW. 10/08/98.

6. Markel, Howard> Final Report of the Tasj Force on Genetic Testing, Appendix 7. Obtained from WWW. 11/03/98.

8. Marshall, Eliot. 1998. DNA Studies Challenge the Meaning of Race. Science. 282(5389): pp 654-655.

9. Mc Carrick, Pat Milmoe. Genetic Testing and Genetic Screening. Obtained from WWW. 10/19/96.

10. Britannica On-line. The Principles of Genetics and Heredity. Obtained from WWW. 11/02/98.

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