Genetic counseling is a communication process by which personal genetic risk information is translated into practical information for families. Genetic counselors are health care professionals with specialized training and experience in the areas of medical genetics and counseling. Genetic counselors are able to assist families by:
- Helping families understand information about birth defects or genetic disorders. This includes explaining patterns of inheritance, recurrence risks, natural history of diseases, and genetic testing options.
- Providing nondirective supportive counseling regarding emotional issues related to a diagnosis or testing options.
- Helping individuals or families make decisions that they are comfortable with based on their personal ethical and religious standards.
- Connecting families with appropriate resources, such as support groups or specific types of medical clinics, locally and nationally.
Types of genetic counseling
Genetic counselors work with people concerned about the risk of an inherited disease. These patients represent several different patient populations. Prenatal genetic counseling is provided to couples that have an increased risk for birth defects or inherited conditions and are expecting a child or planning a pregnancy. Pediatric genetic counseling is provided to families with children suspected of having a genetic disorder or with children previously diagnosed with a genetic disorder. Adult genetic counseling is provided to adults with clinical features of an inherited disease or a family history of an inherited disease. Cancer genetic counseling is provided to those with a strong family history of certain types of cancer.
Prenatal genetic counseling
There are several different reasons a person or couple may seek prenatal genetic counseling. If a woman is age 35 or older and pregnant, there is an increased chance that the fetus may have a change in the number of chromosomes present. Changes in chromosome number may lead to mental retardation and birth defects. Down syndrome is the most common change in chromosome number that occurs more often in the fetuses of older women. Couples may seek prenatal genetic counseling because of abnormal results of screening tests performed during pregnancy. A blood test called the alpha fetal protein (AFP) test is offered to all pregnant women. This blood test screens for Down syndrome, open spine defects (spina bifida) and another type of mental retardation caused by a change in chromosome number called Trisomy 18. When this test is abnormal, further tests are offered to get more information about the chance of these conditions in the fetus. Another reason that people seek prenatal genetic counseling is a family history of birth defects or inherited diseases. In some cases, blood tests on the parents may be available to indicate if their children would be at risk of being affected. Genetic counselors assess risk in each case, help patients understand their risks and explore how patients feel about or cope with these risks.
Prenatal tests that are offered during genetic counseling include level II ultrasounds, maternal serum AFP screening, chorionic villus sampling (CVS), and amniocentesis. Level II ultrasound is a detailed ultrasound surveying fetal anatomy for birth defects. Ultrasound is limited to detection of structural changes in anatomy and cannot detect changes in chromosome number. The maternal serum AFP screening is used to indicate if a pregnant woman has a higher or lower chance of certain birth defects. This test can only change the chances for a birth defect. The screening cannot diagnose a birth defect. CVS is a way of learning how many chromosomes is present in a fetus. A small piece of placental tissue is obtained for these studies during the tenth to twelfth weeks of pregnancy. Amniocentesis is also a way of learning how many chromosomes are present in a fetus. Amniotic fluid is obtained for these studies, usually between 16 and 18 weeks of pregnancy. There is a small risk for miscarriage with both of these tests. Genetic counseling regarding these procedures involves the careful explanation of benefits and limitations of each testing option. The counselor also tries to explore how patients feel about prenatal testing and the impact of such testing on the pregnancy. Genetic counselors are supportive of any decision a patient makes about whether or not to have prenatal tests performed.
Pediatric genetic counseling
Families or pediatricians seek genetic counseling when a child has features of an inherited condition. Any child who is born with more than one birth defect, mental retardation, or dysmorphic features has an increased chance of having a genetic syndrome. A common type of mental retardation in males for which genetic testing is available is fragile X syndrome. Genetic testing is also available for many other childhood illnesses such as hemophilia and muscular dystrophy. Genetic counselors work with medical geneticists to determine if a genetic syndrome is present. This process includes a careful examination of family history, medical history of the child, review of pertinent medical records in the family, a physical examination of the child, and sometimes blood work or other diagnostic tests. If a diagnosis is made, then the medical geneticist and genetic counselor review what is known about the inheritance of the condition, the natural history of the condition, treatment options, further examinations that may be needed for health problems common in the diagnosed syndrome and resources for helping the family. The genetic counselor also helps the family adjust to the diagnosis by emotional support and counseling. Many families are devastated by receiving a diagnosis, learning of the likely outcome for the child, and by the loss of the hoped-for healthy child. There would also be a discussion about recurrence risks in the family and who else in the family may be at risk.
Adult genetic counseling
Adults seek genetic counseling when a person in the family decides to be tested for a known genetic
condition in the family, when an adult begins exhibiting symptoms of an inherited condition or when there is a new diagnosis of someone with an adult onset disorder in the family. In addition, sometimes the birth of a child with obvious features of a genetic disease leads to diagnosis of a parent who is affected more mildly. Genetic counseling for adults may lead to the consideration of presymptomatic genetic testing. Testing a person to determine if they will be symptomatic for a condition before the symptoms occur is an area of controversy. Huntington disease is an example of a genetic disease for which presymptomatic testing is available. Huntington disease is a neurological disease resulting in dementia. Onset of the condition is between 30 to 50 years of age. Huntington disease is inherited in an autosomal dominant pattern. If a person has a parent with the disease, their risk of being affected is 50%. Would presymptomatic testing relieve or create anxiety? Would a person benefit from removal of doubt about being affected? Would knowing help a person with life planning? Genetic counselors help patients sort through their feelings about such testing and whether or not the results would be helpful to them.
Cancer genetic counseling
A family history of early onset breast, ovarian, or colon cancer in multiple generations of a family is a common reason a person would seek a genetic counselor that works with cancer patients. While most cancer is not inherited, there are some families in which a dominant gene is present and causing the disease. The genetic counselor is able to discuss with a patient the chance that the cancer in the family is related to a dominantly inherited gene. The counselor can also discuss the option of testing for the breast and ovarian cancer genes, BRCA1 and BRCA2. In some cases the person seeking testing has already had cancer, and in others they have not. Therefore, presymptomatic testing is also an issue in cancer genetics. Emotional support is important for these patients as they have often lost close relatives from cancer and are fearful of their own risks. For families in which a dominant form of cancer is detected through genetic testing, a plan for increased surveillance for the disease can be made.
In all types of genetic counseling, an important aspect of the genetic counseling session is information
In taking a family history, a genetic counselor asks the patient's ethnicity or ancestral origin. There are some ethnic groups that have a higher chance of being carriers of some genetic diseases. For instance, the chance that an African American is a carrier of a gene for sickle cell disease is 1/10. People of Jewish ancestry are more likely to be carriers of several conditions including Tay-Sachs disease, Canavan disease and cystic fibrosis. People of Mediterranean ancestry are more likely to be carriers of a type of anemia called thalassemia. Genetic counselors discuss inheritance patterns of these diseases, carrier risks, and genetic screening or testing options.
Another question a genetic counselor asks in taking a family history is if the couple is related to one another by blood. The practice of marrying or having children with relatives is infrequent in the United States, but is more common in some countries. When two people are related by blood, there is an increased chance for their children to be affected with conditions inherited in a recessive pattern. In recessive inheritance, each parent of a child affected with a disease carries a single gene for the disease. The child gets two copies, one from each parent, and is affected. People who have a common ancestor are more likely than unrelated people to be carriers of genes for the same recessively inherited genes. Depending on family history and ethnic background, blood tests can be offered to couples to get more information about the chance for these conditions to occur.
Exposures during pregnancy
During prenatal genetic counseling, the counselor will ask about pregnancy history. If the patient has taken a medication or has had a harmful exposure (like radiation), the genetic counselor can discuss the possibility of harmful affects. Ultrasound is often a useful tool to look for some affects of exposures.
Ethical issues in genetic counseling
Prenatal diagnosis of anomalies or chromosomal abnormalities leads to a decision about whether or not a couple wishes to continue a pregnancy. Some couples chose to continue a pregnancy. Prenatal diagnosis gives them additional time to emotionally prepare for the birth of the child and to gather resources. Others choose not to continue a pregnancy in which problems have been diagnosed. These couples have unique emotional needs. Often the child is very much a desired addition to the family and parents are devastated that the child is not healthy. Presymptomatic testing for adult onset disorders and cancer raise difficult issues regarding the need to know and the reality of dealing with abnormal results before symptoms. The National Society of Genetic Counselors has created a Code of Ethics to guide genetic counselors in caring for patients. The Code of Ethics consists of four ethical principles:
- Beneficience is the promotion of personal well being in others. The genetic counselor is an advocate for the patient.
- Nonmaleficience is the idea of doing no harm to a patient.
- Autonomy is recognizing the value of the individual, the person's abilities and their point of view. Important aspects of autonomy are truthfulness with patients, respecting confidentiality, and practicing informed consent.
- Justice is providing equal care for all, freedom of choice, and providing a high quality of care.
Perhaps the main ethical principle of genetic counseling is the attempt to provide nondirective counseling. This principle again points to a patient centered approach to care by focusing on the thoughts and feelings of the patient. Five percent of the Human Genome Project budget is designated to research involving the best way to deal with ethical issues that arise as new genetic tests become available. Genetic counselors can help patients navigate through the unfamiliar territory of genetic testing.
Baker, Diane. A Guide to Genetic Counseling. New York: John Wiley and Sons, Inc., 1998.
Harper, Peter S. Practical Genetic Counseling. Oxford: Butterworth Heinmann, 1998.
American Society of Human Genetics. 9650 Rockville Pike, Bethesda, MD 20814-3998. (301) 571-1825. <http://www.faseb.org/genetics/ashg/ashgmenu.htm>.
March of Dimes Birth Defects Foundation. 1275 Mamaroneck Ave., White Plains, NY 10605. (888) 663-4637. firstname.lastname@example.org. <http://www.modimes.org>.
National Society of Genetic Counselors. 233 Canterbury Dr., Wallingford, PA 19086-6617. (610) 872-1192. <http://www.nsgc.org/GeneticCounselingYou.asp>.
Sonja Rene Eubanks, MS, CGC