Friday, March 31, 2006

Genetic Counseling

If you and your partner are newly pregnant, you may be amazed at the number and variety of prenatal tests available to you. Blood tests, urine tests, monthly medical exams, diet questionnaires, and family history forms crowd your schedule and your desk, but each of these tests helps to assess the health of you and your baby - and to predict any potential health risks.
Unlike your parents, you may also have the option of genetic testing. These tests identify the likelihood of passing certain genetic diseases or disorders (those caused by a defect in the genes - the tiny, DNA-containing units of heredity that determine the characteristics and functioning of the entire body) to your children.
Some of the more familiar genetic disorders are:
Down syndrome
cystic fibrosis
sickle cell anemia
Tay-Sachs disease (a fatal disease affecting the central nervous system)
If your history suggests that genetic testing would be helpful, you may be referred to a genetic counselor. Or, you might decide to seek out genetic counseling yourself.
But what do genetic counselors do, and how can they help your family-to-be?
What Is Genetic Counseling?
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 genetic conditions, such as Down syndrome, are not inherited. In general, they result from an error (mutation) 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. more...

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