Genetic Techniques in Public Health

Recent advances in human genetics have brought high expectations for implementing prevention strategies among genetically susceptible individuals. Yet the clinical use of this information poses risks as well. It is the role of public health to develop intervention strategies for diseases with a genetic component, implement pilot demonstration programs, and evaluate the impact of the intervention on reducing morbidity and mortality in the population. This evaluation includes conducting a needs assessment of genetic services, studying the impact of genetic counseling on public health, and applying prevention-effectiveness principles to genetics programs. Policy analysis of informed consent to genetic testing, stigmatization of individuals and groups, discrimination in employment, and access to insurance need to be considered.

The two recently identified susceptibility genes BRCA1 and BRCA2, which are associated with a high risk of developing breast and ovarian cancers, illustrate some of the complexities individuals from high-risk families face. Studies to determine the efficacy of prophylactic surgeries, chemoprophylactic strategies, and other preventive measures have not been conclusive, leaving individuals from high-risk families—and those who are carriers of mutations—with complex decisions concerning genetic testing and medical intervention.

Newborn screening illustrates the evolution of effective genetic-screening programs. Recognizing the potential importance of phenylketonuria screening over forty years ago, the Children's Bureau (now called the Maternal and Child Health Bureau) sponsored a multistate urine-screening program. The initial outcome was that 30 percent of infants remained untested due to inadequate specimen-collection and delivery. There was sometimes a false-positive reading. Improvements were made, and today a single drop of blood, rather than a urine sample, is sufficient for eight to ten assays for metabolic-disease indicators, along with genetic and infectious information about the mother.

Another example of an evolving genetic-screening program involves the common abnormal hemoglobin "S," or sickle hemoglobin, detected in newborn-screening programs in the United States. This hemoglobin is the defining characteristic for sickle cell disease. The first statewide screening program was established in 1975. Widespread acceptance and implementation was lacking until after a 1986 study showed the efficacy of daily oral penicillin prophylaxis in preventing infection among young children with sickle cell anemia. The efficacy of sickle cell screening was demonstrated through epidemiological efforts to evaluate pediatric outcomes after newborn screening, by demonstrating that mortality rates declined from 1968 to 1992, particularly in cohorts of sickle cell patients.