Prenatal Genetics, Diagnosis and Counseling

Our genetic counselors help patients:

• Understand when to screen for inherited diseases;
• Interpret the results of genetic and chromosome tests;
• Help determine the best approach for chromosome screening and diagnostic testing;
• Review family histories of concern;
• Provide in-depth information concerning exposures during pregnancy;
• Organize care for pregnancies with genetic conditions, chromosome abnormalities or birth defects.

Before a genetic counseling appointment, patients are encouraged to speak with their family members and their partner’s family members about the following:

• Pregnancies or children born with birth defects such as heart defects, cleft lip and/or palate, clubfeet;
• Pregnancies or children with chromosome abnormalities;
• Genetic conditions such as cystic fibrosis, blood disorders, hemophilia, muscular conditions, neurologic conditions;
• Learning disabilities, intellectual disabilities or autism;
• Reproductive history including premature ovarian failure/insufficiency, multiple (more than three) miscarriages, stillbirths or infant deaths;
• Ethnicity or countries of origin prior to the United States.

If there is a specific genetic condition in the family, it is important to obtain copies of evaluations and genetic testing results.

Our team offers comprehensive diagnostic testing for patients during their pregnancy when an increased risk for a genetic condition is identified, including:

Screening Tests
Tests such as maternal serum screening or cell-free DNA may be performed to identify an increased risk for a chromosome condition such as Down syndrome.

Genetic Carrier Testing
Genetic carrier testing can identify whether a couple is at risk for have a children with an inherited genetic condition.

Ultrasound
Ultrasound may be performed during pregnancy to identify a birth defect.

In situations like these, our team provides education and support to patients to determine further testing and management options. In some cases, patients may choose to have additional diagnostic testing, such as:

Amniocentesis
During amniocentesis a small sample of the fluid that is around the baby (amniotic fluid) is removed from the uterus for testing.

Chorionic Villus Sampling
During chorionic villus sampling (CVS) a small piece of the placenta (chorionic villi) is removed from the placenta for testing.

Percutaneous Umbilical Blood Sampling (PUBS)
Percutaneous umbilical blood sampling is performed under ultrasound guidance to remove a sample of fetal blood.

If an amniocentesis, chorionic villus sampling or PUBS is planned:

• Patients who regularly take aspirin or a blood thinner should discuss with their health care provider if the medication should be stopped temporarily;
• Allow time for both the counseling appointment and procedure. A genetic counseling appointment is generally one hour and a diagnostic procedure can require an additional hour including the ultrasound time and the procedure itself;
• Patients should be able to drive home after the procedure;
• For 24 hours after the procedure, patients should restrict physical activity such as exercise programs, strenuous work and lifting over 15 pounds; bed rest is not needed.

Typically, diagnostic testing is performed to obtain fetal cells for genetic testing of the chromosomes or DNA. Chromosomes are made up of DNA and groups of DNA in specific patterns are called genes. Diagnostic testing may include:

Karyotype
A picture of the chromosomes that detects whole extra or missing chromosomes or large chromosome variations.

Chromosomal Microarray
DNA testing of the chromosomes that detects extra or missing chromosomal material in greater detail than a karyotype. Chromosome microarray does not test for single-gene conditions or provide information about how genes work.

Single Gene Conditions
Targeted DNA testing may be performed to look at a specific gene associated with a constellation of birth defects. Decisions about single gene testing are made based on the clinical information and known genetic causes. In some cases, further genetic testing can involve examination of specific panels of genes or the exome.

For families expecting the birth of a child with a birth defect or genetic condition, coordinated care including high risk obstetric care, neonatology and pediatric subspecialty care are arranged.

After a pregnancy loss or delivery of a child with birth defects, families have questions about why such an event happened and the impact for future pregnancies. While there are many causes for birth defects and pregnancy loss, genetic testing may detect a specific genetic cause. Additional genetic testing may be suggested to understand recurrence risks in future pregnancies.

Chromosome testing through chromosome microarray is recommended. Even if this testing is normal, it does not rule out an underlying genetic cause. Innovative genetic testing including single-gene testing, directed gene panels and exome sequencing may provide additional information.

Based on clinical information and genetic testing, our team can review testing options for a future pregnancy. If a known genetic cause is identified, diagnostic testing such as CVS or amniocentesis can be offered in a future pregnancy. There may also be an option for pre-implantation genetic diagnosis (PGD), detailed below. Even if there is no known genetic cause, screening by ultrasound or other imaging, such as an MRI or echocardiogram, may also be beneficial.

Pre-implantation genetic diagnosis (PGD) allows for genetic testing of embryos following in-vitro fertilization. PGD increases the probability that the embryos transferred will be unaffected for the disease tested. PGD is only possible for conditions where there is a known genetic cause. Genetic counselors work in conjunction with the fertility specialists in the BWH Center for Infertility and Reproductive Surgery to coordinate this testing.

Our genetic counselors provide educational programs and support to physicians and their office staff. Advances in the decoding of the human genome often places genetic testing, as well as the interpretation and application of these tests, in the physician’s office. Programs taught by genetic counselors can support implementation of prenatal genetic services to the obstetric community.

To schedule an appointment or to learn more about our services, please contact us at (617) 732-4840.

Our offices are located at:

Brigham and Women’s Hospital
CWN-3
75 Francis Street
Boston, MA 02115

Prenatal Genetics, Diagnosis and Counseling Program Leaders

Louise E. Wilkins Haug, MD, PhD
Division of Maternal-Fetal Medicine

Rosemary E. Reiss, MD
Division of Maternal-Fetal Medicine