Genetic Counseling

Genetic counseling is a service to help individuals and families translate scientific knowledge into practical information. A genetic counselor works with a person or family that may be at risk for an inherited disease or abnormal pregnancy outcome, discussing their chances of having children who are affected.

Genetic counseling is the process of:

- evaluating family history and medical records
- ordering genetic tests
- evaluating the results of this investigation
- helping parents understand and reach decisions about what to do next

Genetic tests are done by analyzing small samples of blood or body tissues. They determine whether you, your partner, or your baby carry genes for certain inherited disorders.

Genes are made up of DNA molecules, which are the simplest building blocks of heredity. They're grouped together in specific patterns within a person's chromosomes, forming the unique "blueprint" for every physical and biological characteristic of that person.

Humans have 46 chromosomes, arranged in pairs in every living cell of our bodies. When the egg and sperm join at conception, half of each chromosomal pair is inherited from each parent. This newly formed combination of chromosomes then copies itself again and again during fetal growth and development, passing identical genetic information to each new cell in the growing fetus. Current science suggests that human chromosomes carry from 25,000 to 35,000 genes. An error in just one gene (and in some instances, even the alteration of a single piece of DNA) can sometimes be the cause for a serious medical condition.

Some diseases, such as Huntington's disease (a degenerative nerve disease) and Marfan syndrome (a connective tissue disorder), can be inherited from just one parent. Most disorders cannot occur unless both the mother and father pass along the gene. Some of these are cystic fibrosis, sickle cell anemia, and Tay-Sachs disease. Other non-disjunction genetic conditions, such as Down syndrome, are not inherited. In general, they result from an error in the cell division process during conception or fetal development. Still others, such as achondroplasia (the most common form of dwarfism), may either be inherited or the result of a genetic mutation.

Genetic tests don't yield easy-to-understand results. They can reveal the presence, absence, or malformation of genes or chromosomes. Deciphering what these complex tests mean is where a genetic counselor comes in.

Who Are Genetic Counselors?

Genetic counselors are professionals who have completed a master's program in medical genetics and counseling skills. They then pass a certification exam administered by the American Board of Genetic Counseling. Genetic counselors can help identify and interpret the risks of an inherited disorder, explain inheritance patterns, suggest testing, and lay out possible scenarios. (They refer you to a doctor or a laboratory for the actual tests.) They will explain the meaning of the medical science involved, provide support, and address any emotional issues often raised by the results of the genetic testing.

Who Should See One?

Most couples planning a pregnancy or who are expecting don't need genetic counseling. About 3% of babies are born with birth defects each year, according to the U.S. Centers for Disease Control and Prevention - and of the malformations that do occur, the most common are also among the most treatable. Cleft palate and clubfoot, two of the more common birth defects, can be surgically repaired, as can many heart malformations.

The best time to seek genetic counseling is before becoming pregnant, when a counselor can help assess your risk factors. But even after you become pregnant, a meeting with a genetic counselor can still be helpful. For example, several babies have been diagnosed with spina bifida before birth. Recent research suggests that delivering a baby with spina bifida via cesarean section (avoiding the trauma of travel through the birth canal) can minimize damage to the baby's spine - and perhaps reduce the likelihood that the child will need a wheelchair.

You should consider genetic counseling if any of the following risk factors apply to you:

- if a standard prenatal screening test (such as the alpha fetoprotein test) yields an abnormal result
- if an amniocentesis yields an unexpected result (such as a chromosomal defect in the unborn baby)
- if either parent or a close relative has an inherited disease or birth defect
- if either parent already has children with birth defects or genetic disorders
- if the mother-to-be has had two or more miscarriages or babies that died in infancy
- if the mother-to-be will be 35 or older when the baby is born (Chances of having a child with Down syndrome increase with the mother's age: a 35-year-old woman has a one in 350 chance of conceiving a child with Down syndrome. This chance increases to one in 110 by age 40 and one in 30 by age 45.)
- if parents are concerned about genetic defects that occur frequently in their ethnic or racial group (For example, couples of African descent are most at risk for having a child with sickle cell anemia; couples of central or eastern European Jewish (Ashkenazi) or Cajun descent may be carriers of Tay-Sachs disease; and couples of Asian, Italian, Greek, or Middle Eastern descent may carry the gene for thalassemia, a red blood cell disorder.)

What Happens at a Genetic Counseling Appointment?

When you go to see a genetic counselor, he or she:

- Will record your family history (for instance, if your parents, grandparents or siblings had heart disease, diabetes, etc.) and your own medical background.
- May arrange appointments for blood tests, physical exams, or amniocentesis.
- Will try to put together a picture of how your family's health may affect your children.
- Will help you interpret medical information about any risks present and explain the role of genetics in these conditions. Often genetic counselors can determine the risk of occurrence or recurrence of a condition and the availability of tests for it.

Evaluation of tests results usually is coordinated between the genetic counselor, the person or couple and the doctor. In the occasional case of troubling results, the counselor will provide information to help you make decisions. The counselor or the doctor can refer you to resources in your community that deal with a specific genetic condition, or to medical specialists, educational specialists or family support groups