Genetic Counseling Health Article

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 her 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 proportionally 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 actually occurring 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 of 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 persons to understand their risks, and explore how they feel about or will 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 ultra-sound 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 having a child with certain birth defects. This test can only provide information concerning the probability of a birth defect. The screening cannot diagnose an actual birth defect. CVS is a way of learning how many chromosomes are 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 15 and 20 weeks of pregnancy. There is a small risk of miscarriage associated with both of these tests. Genetic counseling regarding these procedures involves the careful explanation of benefits and limitations of each testing option. A genetic counselor also tries to explore how persons feel about prenatal testing and the impact of such testing on the pregnancy. Genetic counselors are supportive of any decision a person 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 a 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 providing 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.