Genetic Counseling & Screening
by Yael Rosenberg, RN
• Genetic Screening – An Overview
• Genetic Counseling
• Genetic Screening and Testing – A Directory
Genetic Screening – An Overview
The first step towards unraveling the mysteries behind genetic disorders is to find the problem genes. Many defective genes have been identified and work is ongoing to discover feasible methods for "cures". While investigations of genetic treatments continue, people are in a position to begin using the current facts for their benefit.
Gene tests (also called DNA-based tests), the newest and most sophisticated of the techniques used to test for genetic disorders, involve direct examination of the DNA molecule itself. Other genetic tests include biochemical tests for such gene products as enzymes and other proteins and for microscopic examination of stained or fluorescent chromosomes. Genetic tests are used for several reasons, including:
• Carrier screening, which involves identifying unaffected individuals who carry one copy of a gene for a disease that requires two copies for the disease to be expressed;
• Prenatal diagnostic testing;
• Newborn screening;
• Pre-symptomatic testing for predicting adult-onset disorders;
• Pre-symptomatic testing for estimating the risk of developing adult-onset genetic disorders, cancers, and Alzheimer's disease;
• Confirmational diagnosis of a symptomatic individual; and
• Forensic/identity testing.
In gene tests, scientists scan a patient's DNA sample for mutated sequences. A DNA sample can be obtained from any tissue, including blood. For some types of gene tests, researchers design short pieces of DNA called probes, whose sequences are complementary to the mutated sequences. These probes will seek their complement among the three billion base pairs of an individual's genome. If the mutated sequence is present in the patient's genome, the probe will bind to it and flag the mutation. Another type of DNA testing involves comparing the sequence of DNA bases in a patient's gene to a normal version of the gene. Cost of testing can range from hundreds to thousands of dollars, depending on the sizes of the genes and the numbers of mutations tested.
There are hundreds of genetic diseases, but a select group is known to affect people of Jewish descent in particular. If you are planning to have a baby, it is recommended that you speak with a Genetic Counselor, if for no other reason than becoming informed and making intelligent decisions.
Genetic Counselors are health professionals with specialized master's degrees and experience in the areas of medical genetics and counseling. Genetic counselors work as members of a health care team, providing information and support to families who have members with birth defects or genetic disorders and to families who may be at risk for a variety of genetic conditions. They identify families at risk, investigate problems present in the family, interpret information about the inheritance patterns and risks of recurrence and review available options with the family.
Genetic counselors also provide supportive counseling to families, serve as patient advocates, and refer individuals and families to community or state supported services. They serve as educators and resource people for other health care professionals and for the general public. Many counselors also engage in research activities related to the field of genetic counseling and/or medical genetics (National Society of Genetic Counselors).