Magazine article National Forum

Secretary's Advisory Committee on Genetic Testing

Magazine article National Forum

Secretary's Advisory Committee on Genetic Testing

Article excerpt

Its Emerging Role in Public Policy Deliberation on Genetic Tests

The Secretary's Advisory Committee on Genetic Testing (SACGT) was established by the U.S. Secretary of Health and Human Services, Donna E. Shalala, to provide a public forum for the formulation of policy advice in the complex and growing area of genetic testing. After a careful nomination and selection process, the Secretary announced the appointment of thirteen advisors to the SACGT in June 1999. The first meeting of the SACGT was held June 30, 1999. This article describes the purpose, formation, and function of the SACGT. Before addressing these questions about the role of the SACGT, we first will explain what genetic testing is, how it is currently used, and what new uses it may be put to in the future.

WHAT IS GENETIC TESTING?

Genetic testing is the analysis of genes or gene products to detect mutations that result in genetic disease or increase a person's susceptibility to disease. A mutation is the omission, addition, or alteration of one or more nucleotides, the building blocks of genes. When a mutation occurs, the gene may not be able to produce the protein it is meant to make or may produce an altered form or too much or too little of the protein. Sometimes an entire gene is absent, and the protein it is programmed to produce cannot be made. In other instances, genes switch locations and are inappropriately or permanently turned on or off. When such events occur, chemical processes or reactions in which the protein is involved may happen incorrectly or not at all, leading to a genetic disease.

Mutations can be inherited or develop throughout one's lifetime. Inherited mutations are found in every cell of the body, whereas acquired mutations occur sporadically in individual cells. Currently, more than 4,000 diseases are thought to stem from inherited gene mutations. Some of these diseases, such as sickle cell anemia and cystic fibrosis, are caused by a single gene mutation while others, such as heart disease and most cancers, arise from a complex interplay between multiple genes and between genes and environmental factors.

Genetic testing detects mutations in several ways. DNA and its nucleotides, taken from cells in a sample of blood or from other body fluids and tissues, can be analyzed to detect alterations in the biochemical composition of DNA, in chromosomes, or in gene sequences, indicating the possibility of genetic disease. Genetic tests can also use RNA (DNA directs the production of RNA, which directs the production of proteins) to detect inheritable disease-related mutations. In addition, mutations can be detected by biochemical testing for the presence or absence of key proteins or metabolites that signal aberrant genes.

Newborn screening, which is mandated by law in most states, is currently the most common form of genetic testing. Every infant born in the United States today is screened for phenylketonuria and congenital hypothyroidism, and those born in certain states are screened for additional disorders. Genetic testing is also performed for other purposes, including to establish prenatal and clinical diagnoses, to determine paternity, and to aid forensic investigations. Increasingly, it is used to predict an individual's risk of developing a genetic disease in the future and to identify carriers, individuals who will not develop the disease themselves but may conceive a child who will have the disease. In addition, genetic tests are used to test for genetic defects arising from acquired diseases such as genetic cancers.

According to GeneTests(TM), a directory of clinical laboratories providing testing for genetic disorders, genetic testing is clinically available for 339 diseases, and more than 216 laboratories in the United States perform such tests. Testing is available for an additional 325 diseases on a research basis only;194 laboratories conduct these research tests. Most of these tests are for rare, single or contiguous gene disorders and are used to make or confirm a diagnosis. …

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