Genetic Testing and Counseling Services

Genetic counseling involves educating families and individuals about their risk of passing on certain inherited diseases to their offspring. If a pregnancy is already underway, genetic counselors can determine if a fetus has an inherited disease or disability. Certified by the American Board of Genetic Counseling, each member of our staff has an advanced degree in medical genetics and counseling. These knowledgeable, caring professionals provide:

• Information and guidance for women who want a baby but are at an elevated risk for passing on a genetic abnormality
• Pre-pregnancy education and counseling
• Interpretation of test results
• Guidance to prepare for raising a child with a physical or mental disorder
• Referrals to other medical services

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Inherited diseases

Genetic counseling begins with a detailed family history, followed by specialized testing. This includes an analysis of blood, amniotic fluid or tissue samples to determine the biochemical, chromosomal or genetic markers that can designate the presence or absence of specific inherited diseases.

In most cases, prenatal tests indicate only the potential for a certain disease, not the certainty. Currently, there are about 250 birth defects that can be diagnosed in fetuses, including:

• Cystic fibrosis
• Down syndrome
• Huntington's disease
• Sickle cell anemia
• Spina bifida
• Tay-Sachs disease
• Thalassemia

Risk Factors

Both genetics and the environment in which a fetus develops play a critical role in whether a baby will be born with physical or mental defects. There are a number of common factors that, statistically, place a baby at greater risk, including:

• Family history of genetic disorders
• Mothers who are over age 35 at time of conception
• Mothers with a history of miscarriages or infertility
• Mothers with chronic diseases
• The presence of two or more fetuses

Genetic Testing

The board-certified medical geneticists at UC Irvine Medical Center offer a variety of prenatal tests to determine genetic and physical development. Many of these involve DNA screening, while others examine the baby’s physical structure. A few of the more common procedures include:

• Amniocentesis. This is the most frequently used genetic test, particularly in women over age 35, when the risk of having a Down syndrome baby outweighs the risk of miscarriage. It is performed when enough fluid has accumulated in the sac surrounding the fetus—usually between the 14th and 20th week of gestation. Using a thin needle, a physician extracts a small sample of fluid, which contains DNA from the fetus’s skin cells, as well as other cells. Analysis of the sample determines whether the genetic markers for Down syndrome and/or other genetic abnormalities exist.
• Chorionic villus sampling (CVS). Because it can be performed earlier than amniocentesis—at the 10th to 13th week of gestation—this procedure is becoming increasingly popular. CVS involves retrieval of a small sample of the placenta, which carries the same DNA as that of the fetus.
• Combined first trimester screening (CFTS). This test for the risk of chromosomal defects offers a distinct advantage over amniocentesis and CVS: It is totally noninvasive. Results of a blood test and an ultrasound scan of the fluid under the skin of the fetus’s neck are reviewed to determine—with approximately 90 percent accuracy—whether or not the developing baby may carry the genes for Down syndrome or trisomy-18.
• Maternal Blood Screening/Triple Screen/Quadruple Screen. This test measures the level of alpha-fetoprotein (AFP) in the mother’s blood. Produced by the fetus, AFP can indicate a problem when it is above or below normal limits. The triple screen also detects estriol and human chorionic gonadotropin (HCG), while the quadruple screen includes inhibin-A. The more markers, the greater the accuracy of the screening, which can detect Down syndrome and spina bifida.
• Prenatal ultrasound. This noninvasive diagnostic tool uses sound waves to produce an image of the infant. While ultrasound is quite useful as a means to examine the physical structure of the baby, it provides few, if any, clues about genetic development. But it is valuable in detecting structural defects such as spina bifida and anencephaly, a defect of the neural tube.
• Fetal echocardiography. This specialized ultrasound test examines the functioning of the developing baby’s heart.

Genetic Counseling

Although genetic testing cannot indicate the severity of a disease, it can sometimes be very helpful for potential parents. If a test for a disease-related gene is negative, there is comfort in knowing it is not a problem---and never will be. If the result is positive, patients may choose not to become pregnant. If already pregnant, they can make decisions based on test results, including preparing themselves and their families for the arrival of a sick or disabled child. During this complex process, our genetic counselors provide support and education, helping patients interpret the information available to them.

Coordination of Care

UC Irvine Medical Center’s multidisciplinary team of physicians, nurses, technologists and others offers a continuum of care throughout the entire obstetrical experience, from genetic counseling and pregnancy planning through postpartum care. In the case of genetic testing, patients are referred to appropriate resources inside the hospital and in the community when genetic abnormalities are detected. Throughout this process, emphasis is placed on close communication between various team members and the patient and her significant others.