Genetic Testing and Genetic Screening

In recent years there has been an enormous expansion in the knowledge that may be gleaned from the testing of an individual's genetic material to predict present or future disability or disease either for oneself or one's offspring. The Human Genome Project, which is currently mapping the entire human gene system, is identifying progressively more genetic sequencing information (see Scope Note 17, The Human Genome Project). Information obtained from genetic testing raises ethical and legal questions about its uses by society. The ethical dilemmas were foreseen two decades ago by bioethicists who asked whether questionable applications could stop "legitimate pursuits" (IV, Gaylin 1972) and whether genetic disease might come to be viewed as "transmissible" in the sense of being contagious (IV, Veatch 1974).

Not only has knowledge expanded, but the practice of genetic testing and screening has greatly increased as well. For example, in the case of testing for cystic fibrosis (CF), the U.S. Congress' Office of Technology Assessment (OTA) estimates that instances of screening jumped from 9310 tests in 1991 to 63,000 tests in 1992 (I, OTA [Cystic Fibrosis] 1992). In addition, the OTA estimates that within the next few years, the six million women who become pregnant each year routinely will be informed of available CF carrier tests (I, OTA [Cystic Fibrosis] 1992).

Following the recent identification of a gene linked to breast cancer, Dr. Francis Sellers Collins, director of the National Center for Human Genome Research, said that "it is not inconceivable that every woman in America may want to be screened for this gene. The economic, ethical, and counseling issues will be very daunting." Dr. Collins opines that in the near future physical examinations for 18-year-olds will include DNA testing for diseases with genetic components and that physicians, in the interests of preventive medicine, will make risk-based recommendations for a healthy life-style (IV, Breo 1993). The U.S. President's Commission for the Study of Ethical Problems in Medicine and Biomedical and Behavioral Research predicted as early as 1983 that before the end of the century genetic screening and counseling would become major components of both public health and individual medical care (I, U.S. President's Commission 1983).

The OTA defines genetic testing as "the use of specific assays to determine the genetic status of individuals already suspected to be at high risk for a particular inherited condition. The terms genetic test, genetic assay, and genetic analysis are used interchangeably to mean the actual laboratory examination of samples." In contrast, genetic screening usually uses the same assays employed for genetic testing but is distinguished from genetic testing by its target population (I, OTA [Genetic Monitoring] 1990). The National Academy of Sciences (NAS) defines screening as the systematic search of populations for persons with latent, early, or asymptomatic disease (III, NAS 1975). Some of the literature annotated for this Scope Note appears to use the terms "testing" and "screening" interchangeably.

Philip Boyle of the Hastings Center points out that the language used to describe genetic variation is important and asks what words should be used: "Defects, flaws, deleterious genes, disorders, or the more neutral conditions? Using words such as normal—and its corollary, abnormal—is likely to foster stigmatization and discrimination" (III, Genetic Grammar, Boyle 1992).

Areas of focus in genetic testing include: prenatal diagnosis, newborn screening, carrier screening, forensic screening, and susceptibility screening.

Prenatal diagnosis discerns whether a fetus is at risk for various identifiable genetic diseases or traits. Prenatal diagnosis is made using amniotic fluid, fetal cells, and fetal or maternal blood cells obtained during amniocentesis testing; alpha fetoprotein assays or chorionic villus sampling; or ultrasound tomography, which creates fetal images on a screen. Another method, known as fetoscopy, uses a camera on a needle inserted in the uterus to view the fetus. Since prenatal screening began in 1966 (I, U.S. President's Commission 1983), the number of metabolic defects and genetic disorders that can be diagnosed prenatally has expanded greatly. There is also discussion of requiring testing for parents who are participating in an in vitro fertilization program and are at genetic...