Genetic Screening

Kelly Miller

Copyright 1999

There are numerous genetic disorders present in today's society that produce handicaps and threaten longevity. Genetic determinants are at the root of many cases of infertility, miscarriage, stillbirths, neonatal deaths, multiple malformations, retardation in growth and development, mental illness, and mental retardation. Estimates of the problem's magnitude have been made from data provided by the Department of Health, Education, and Welfare, which suggest that genetic factors are involved in one fifth of infant deaths, one fourth of the institutionalized mental retardates, almost one half of individuals with IQs less than fifty, and half of first trimester abortions (Finley 1982). Genetic screening is the systematic search within a population for persons possessing particular genotypes, which are either associated with disease, predisposing to disease, or leading to disease in descendants (Committee for the study of Inborn Errors of Metabolism 1975; Schriver 1980: as cited by Gitzelmann 1982). Genetic screening is a public health measure of the first order not only because of the huge demand for health care information by large numbers of families with affected members, but because despite this challenge it currently affects the lives of thousands of individuals (Gitzelmann 1982; Finley 1982).

Genetic screening is conducted for the same basic reasons as nongenetic screening, and that is for the care of the ill and prevention of disease. There are several goals of genetic screening, which include medical management or treatment, the provision of reproductive information, enumeration, and research. The main goal is medical management or treatment. Unlike traditional management, which is concerned with the treatment of symptoms and the patient's social adjustment, medical management through genetic screening can actually be preventative in nature. It prevents disease manifestation by helping patients cope with environmental conditions in the face of inadequate genetic endowment. This type of screening began in the early 1960's with the screening for phenylketonuria (PKU) and is currently the most widely practiced. Over the years, more tests have been added for other diseases that like PKU could be discovered by simple tests and treated by following a strict diet (Gitzelmann 1982).

The second goal of genetic screening is the provision of reproductive information. Through simple techniques such as serum enzyme determinations and hemoglobin electrophoresis it is possible to identify individuals possessing genes that will cause serious disease in their offspring. Screening is most efficient if it is conducted to discover couples who are carriers of recessive disease inducing genes that can be diagnosed through amniocentesis. Examples of such diseases are Tay-Sachs disease, Beta thalassemia, and possibly sickle-cell anemia. It was specifically the screening for the Tay-Sachs trait, which began in 1971 that became the model for all carrier screening to follow (Gitzelmann 1982).

The third goal of genetic screening, enumeration, has less immediate application, but serves in future developments. Enumeration (or counting) involves the estimation of the prevalence of mutant alleles, their distribution and biological significance. This type of information will add to the knowledge of human genetic variation and serve as the basis for clarification of the pathogenesis, natural cause, and possibly the treatment of various disorders (Gitzelmann 1982).

The final goal is that of genetic screening for research. Within the category of research, surveys may be done to uncover gene frequencies, polymorphisms, and the genetic heterogeneity of humans as it relates to physical variation. Obviously, safeguards against the risks linked to screening are in greater need in this category as none of the work is done in the interest of an individual patient or their family (Gitzelmann 1982).

Human risks are involved in all genetic screening programs. These risks include labeling, discrimination, loss of self-esteem, prevention or damage to parent-child bonding, stigmatization, unnecessary anxieties and invasion of privacy. For this reason genetic screening is a very powerful approach, which requires careful planning and implementation to avoid abuse (see Figure 1 page 12 for the procedure for evaluating a proposed genetic screening program). The decision to enact a proposed screening program is based on what disease will be the focus of the screening, who should be included in the studies, and what will be the impact on the individual and the family. The usefulness and cost of obtaining the information and the availability of facilities and personnel are also considerations (Finley 1982). Priority of screening programs is assigned based on the incidence of the threatened condition and its severity, as well, as the availability of techniques for discovery, diagnosis, control, and perhaps prevention (Gitzelmann 1982).

Screening programs for sickle-cell disease have shown how negative outcomes can be without proper planning and attention to detail (Karp 1980: as cited by Gizelmann 1982). The genetic screening programs of the 1970's employed the "Sickledex" test, which failed to distinguish between the disease and carrier status. This caused inflation of the estimated numbers affected by the disease, thereby accentuating the problem (Wertz 1996). These programs have become examples of what not to do. They were originally generated through public demand and political pressure. They were begun prematurely, with little regard for potential harmful effects (Hampton et al. 1974: as cited by Gitzelmann 1982). Public education was not provided, counseling was insufficient, and prenatal diagnosis was unavailable (Gitzelmann 1982).

Legal liability issues have arisen with the scientific advances in genetic screening. Malpractice litigation has exploded reflecting the increased expectations of high-quality, disappointment-free medical care (Wright and Shaw 1981). The legal principles not only require a well-planned screening program, but as a report from the National Academy of Science reasons, all the stipulations of informed consent in the doctor-patient relationship must be met (Fletcher 1981).

In order to develop an informed decision-making client, counseling for genetic disorders becomes necessary (Headings 1982). Genetic counseling involves the advisement of patients on the difficulties that may arise from genetic disease. Patients must be informed of the medical facts, severity and prognosis of the genetic disorder, the risk of its reoccurrence, and the options available for the management of the disorder. Indications for referral to a genetic counseling center according to the Council on Scientific Affairs (1982) are as follows:

"...1) genetic or congenital anomaly in a family member, 2) family history of an inherited disorder, 3) abnormal somatic or behavioral development, 4) mental retardation of unknown etiology in a child born previously, 5) pregnancy in an older woman (> 35 years), 6) specific ethnic background that may suggest a high rate of genetic abnormality, 7) drug-use or long-term exposure to teratogens or mutagens, 8) three or more spontaneous abortions, early infant deaths or both, and 9) infertility."

While the sole purpose of genetic screening is to cure disease, it has the potential to strongly influence our society (Blank 1982). Often the options selected by patients are influenced by the numerous social and ethical issues that surround genetic screening (Council on Scientific Affairs 1982). For this reason there are many social, moral and ethical concerns over the public policy for the use of genetic screening. A few of the major issues include the debate over mandatory versus voluntary screening, screening in the workplace, and the most controversial type of screening, prenatal screening.

The debate over mandatory genetic screening is based on the disagreement over both the necessity and right of society to intervene in affected individuals' rights to procreate. So, the major question is whether genetic screening should be considered under the domain of public health policy or remain a private responsibility. The prominent assumption is that a trade-off must exist between the rights of individuals and the rights of society. Since society's concern for the genetic welfare of the population is based on the danger of genetic deterioration is yet unfounded cost/benefit analyses are often employed as strictly utilitarian criteria to determine trade-offs (Blank 1982).

It was determined through prenatal diagnosis that approximately 21,000 babies with chromosomal abnormalities alone are born each year in the USA. Estimates of the worldwide monetary cost of caring for such births worldwide equaled at least $40 billion over 20 years. The cost per resident, as of 1972, in public mental institutions equaled $6,509. Hypothetical situations have been constructed in order to estimate the increased productivity to society if a normal person was born to replace a genetically diseased fetus which, was aborted. Examples are presented in Table 1 (page 12) for selected conditions. Social benefits in this table were measured entirely by savings in medical, educational, and other related costs to society. These types of analyses along with the fears of genetic deterioration often form the basis of advocacy of societal intervention in child-bearing decisions, denial of medical care to congenitally damaged, and sterilization of carriers (Blank, 1982).

Two types of mandatory screening have been established. The first type detects affected individuals so treatment can be provided. The screening of newborns for PKU is the best example of this type. The second type is designed to identify carriers of recessive deleterious genes (Blank 1982).

The law in 43 states mandated PKU screening, as of 1975. Parental objection for any reason was permitted in five of those states, and objection based on religious beliefs was permitted in 30 states (Faden et al. 1982). A majority of individuals with PKU suffer from a deficiency of phenylalanine hydroxlase enzyme, which can lead to mental retardation (Finley 1982). The negative effects of PKU can be avoided if afflicted infants are placed on low phenylalanine diets as early in life as possible. Detection of infants at risk is accomplished through biochemical screening. Blood samples for this type of screening are collected from heel pricks, which are currently the lowest risk medical intervention possible (Faden et al. 1982). The cost of the test is minimal and the blood is sent to the central laboratory on a blotter. This tiny blood sample can also be used for several other tests. The frequency of PKU occurrence is 1 in 20,000 births. The benefits of preventing one case of PKU are easy to estimate when considering the reduction of impact on the family and to the cost of institutionalization of one patient per year. PKU screening can be justified as a public health measure because it meets several criteria defined by the National Research Council and other agencies. These criteria include public benefit and acceptance, the benefits of screening outweigh the costs, appropriate and available public education, satisfactory test methods, lab procedures, reporting procedures, counseling and evaluation (Finley 1982). This type of screening can be supported by the doctrine that the state can act to protect those that can't protect themselves (Blank 1982).

Unlike the mandatory screening for PKU and other similar diseases, which is conducted for the early treatment of individuals already affected by disease, there is little evidence that screening for carriers of genetic disease can meet public health grounds for justification. This type of screening has implications for influencing reproductive decisions. It is only effective "if carriers refrain from reproduction or make use of prenatal diagnosis followed by abortion where appropriate" (Blank 1982). This is all controversial and questionable on the basis of ethics and legality and presents few benefits from the high costs (Blank 1982).

I believe that genetic screening and diagnosis should be conducted on a voluntary basis. While there is a good case for compulsory screening for diseases such as PKU in which the inborn errors in metabolism can effectively be treated, I concede that this type of screening could still potentially interfere with the "respect for individual choice in child-rearing matters" (National Academy of Science 1975: as cited by Blank 1982). Despite the fact that parents may have the freedom of choice after screening that freedom will most definitely be constrained by the results.

In a survey conducted by Faden et al. (1982) parental consent as public policy for neonatal screening was evaluated. This survey followed the 1976 decision by the state of Maryland to adopt a regulation designed to respect the parents' right to refuse neonatal screening. Consent was obtained in Maryland through a standard disclosure form. Prior to reviewing the disclosure form only 53% of the control women had heard of a screening that test for diseases causing retardation, and only 52% reported that they had heard about PKU or other related screening. These numbers along with one of the major reasons for refusal of screening being a poor understanding of it, indicate to me that there is a major problem present in public health education. Rather than establishing mandatory genetic screening to avoid public education, efforts should be made to improve public health education so patients can make informed and voluntary decisions. This study also revealed that there was little evidence that the new regulation resulted in additional costs to the health care system in terms of hospital staff time or in loss of efficiency in the number of infants screened.

Another major issue involves the possibility of including genetic screening as a part of pre-placement and periodic post-employment examinations which are currently recommended or required in the Occupational Safety and Health (NIOSH) criteria documents. Genetic factors are listed in these documents as relevant information for many chemical exposures. The development and use of these tests would be to identify genetic predisposition to workplace health hazards (Omenn 1982). To date, the only widespread use of pre-employnment genetic screening was designed to screen African-American individuals for sickle cell anemia (Wertz 1996).

An example of a potential genetic predisposition due to differences in metabolism would be single gene differences affecting N-acetyl-transferase activity in the liver. "N-acetyl-transferase is known to be involved in acetylation and thus inactivation of arlyamines that are potent bladder carcinogens" (Omenn 1982). Examples of these types of compounds, which are among the most certain occupational carcinogens are Beta -naphthyamine, benzidine (4,4-diaminobiphenyl), 4-aminobiphenyl, and 4-nitrobiphenyl (Omenn 1982).

Another example of a potential genetic predisposition, in this case due to tissue sensitivity, would be hemolysis resulting from a G6PD deficiency. This is an X-linked genetic abnormality, which predisposes affected males to hemolytic crisis from oxidizing drugs, naphthalene, and fava beans. Because such individuals are susceptible to oxidizing agents in the form of drugs there is reason to believe that they may also be susceptible to oxidizing chemicals in the workplace (Omenn 1982).

Some see occupational genetic screening as a potential method of recognizing highly susceptible individuals so that preventive and diagnostic care would be enhanced and more attention would be given to the environment of the workplace. I disagree with mandatory occupational screening based on the risk that responsibility for disease or injury may be shifted to the worker making it possible for them to fall victim to discrimination. If responsibility is shifted to the worker it is also possible that the establishment's need to improve working conditions will be diminished. Occupational genetic screening should be voluntary and conducted under a strict contract, which would eliminate the possibility of dismissal or hiring discrimination based on the results. Strict regulations must also be enforced to ensure that health hazards continue to be managed with the utmost efficiency.

The final issue to be discussed is prenatal diagnosis, which could possibly be the most controversial form of screening. Currently prenatal detection of genetic disorders is accomplished mainly through amniocentesis. This procedure includes the withdrawal of fluid from the amniotic sac and the analysis of the sample through a 12-18 day culturing process. Chromosomal, as well as, biochemical tests can also be run on the amniotic cells. The probability of risk to the fetus with this procedure is less than 0.5%, and no maternal mortality has occurred. At this time there is no large threat that this type of screening will become mandatory as, "there is no evidence that the state has any compelling interest to warrant intrusion into the procreation process on genetic grounds" (Blank 1982). So, the debate is mostly moral in origin.

It is the moral dilemma over abortion that often causes controversy in the practice of prenatal diagnosis. To some, prenatal diagnosis is controversial because the results may be used to justify abortion, which in and of itself is a controversial issue in today's society. Those in opposition consider it to be contrary to the goal of medicine, which is to save lives. Those who support selective abortion do so because they wish to prevent suffering and disease (Fletcher 1981).

Another moral problem involving prenatal diagnosis is the request for amniocentesis in order to determine sex. The reasons for opposition to diagnosis are numerous. These reasons include "sex discrimination, wasting scarce resources, trivialization of the serious reasons required for abortion, and misuse of a tool to be used only for medical indications" (Blank 1982). Those who support this type of screening rely on the fact that an abortion policy exists that protects the freedom of women to control reproduction with the advice of a physician and under this policy there can be no absolute opposition to such requests (Fletcher 1981).

I support prenatal genetic screening, but based on religious and moral beliefs I do not support the use of abortion. The prenatal detection of genetic disease should be used to prepare parents for the important decisions to be made after the birth of the child. Because the techniques used in prenatal diagnosis present low risk to the child and mother and as long as public education and counseling are up-to-date and available, I see no reason why the practice should not be continued.

Genetic screening promises to be an ever-increasing part of health care, because predictive medicine is an important part of preventive medicine. However, proper safeguards are necessary to protect or alleviate the human risks involved. Legislators, health officials, and society representatives must determine appropriate guidelines to ensure health measures, while considering moral and ethical issues. It is also essential that the public understand the aims of screening (Finley 1982).


Blank, R.H. 1982. Public policy implications of human genetic technology: genetic screening. The Journal of Medicine and Philosophy 7: 355-374.
Council on Scientific Affairs. 1982. Genetic counseling and prevention of birth defects. Journal of the American Medical Association 248(2): 221-223.
Faden, R., J. Chwalow, N. Holtzman, and S. Horn. 1982. A survey to evaluate parental consent as public policy for neonatal screening. American Journal of Public Health 72(12): 1347-1352.
Finley, W.H. 1982. Genetic screening: an overview. The Alabama Journal of Medical Sciences 19(2): 147-150.
Fletcher, J.C. 1981. Ethical issues in genetic screening and antenatal diagnosis. Clinical Obstetrics and Gynecology 24(4): 1151-1169.
Gitzelmann, R. 1982. Rationales for genetic screening. Human genetics, Part B: Medical Aspects pp. 425-436.
Headings, V.E. 1982. Educating physicians in the art of counseling for genetic disorders. Perspectives in Biology and Medicine 25(3): 428-435.
Omenn, G.S. 1982. Predictive identification of hypersusceptible individuals. Journal of Occupational Medicine 24(5): 369-374.
Wertz, D. 1996. Sickle Cell Testing: Past and Present. Obtained from the WWW:
Wright, E.E., and M.W. Shaw. 1981. Legal liability in genetic screening, genetic counseling, and prenatal diagnosis. Clinical Obstetrics and Gynecology 24(4): 1133-1149.

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