The Fetal Precision Genetics Program at Boston Children’s Hospital identifies potential genetic conditions in a pregnancy by looking for changes or abnormalities in the fetal DNA.
As part of the Maternal Fetal Care Center (MFCC), in affiliation with Brigham and Women’s Hospital, the Fetal Precision Genetics Program plays a significant role in Boston Children’s comprehensive approach to maternal-fetal and perinatal care.
Our multidisciplinary team includes doctors and genetic counselors from Boston Children’s Hospital, Brigham and Women’s Hospital, and Beth Israel Deaconess Medical Center who specialize in clinical genetics and genomics, genetic counseling, maternal-fetal medicine, and pediatrics.
Why choose fetal genetic testing?
If your prenatal ultrasound shows an abnormal finding, the Fetal Precision Genetics Program can help you navigate the genetic testing process. Our goal is to provide you with information and support to make informed decisions about your pregnancy and fetus.
Our team reviews your ultrasound results, medical information, and family history to determine the most appropriate genetic testing for you. We also work with you to understand your genetic testing results, and work with you to navigate care during and after your pregnancy.
Genetic testing may include noninvasive screening and/or invasive diagnostic procedures. The information found through these tests can provide more targeted care for your current pregnancy and future pregnancies, and it can inform your family about the likelihood of a condition happening again.
How does fetal genetic testing work?
Noninvasive screening obtains DNA from your pregnancy through a blood draw. Invasive testing takes a small sample of placental tissue (chorionic villus sampling) or fluid around the fetus (amniocentesis). We can also perform genetic testing from umbilical cord blood after delivery. These samples are used to screen or test the pregnancy for genetic conditions.
Types of genetic testing
Tests performed using a blood sample from the pregnant person and/or partner:
- Noninvasive prenatal testing (NIPT): NIPT analyzes the DNA circulating in a pregnant person’s blood to determine the risk of specific genetic abnormalities. NIPT is considered a screening test because it does not test the fetus directly.
- Gene carrier screening: A sample of biological parents’ blood or saliva may find a gene change related to ultrasound findings. Gene carrier testing can expand to more than 500 conditions.
Tests performed using a sample from an amniocentesis or chorionic villous sampling (CVS) procedure, or using a sample of umbilical cord blood after birth:
- Chromosome microarray (CMA): CMA looks for missing or extra whole chromosomes, extra or missing pieces of DNA, and copy number variants. Copy number variants are classified into three categories:
- Pathogenic: This variant is linked with medical concerns, which can be syndromic, meaning development and growth are involved, or non-syndromic, meaning linked only to one finding.
- Benign: NOT related to clinical concerns and not reported.
- Uncertain: When neither benign nor pathogenic can be decided yet. Eighty percent of uncertain copy number variants are ultimately reclassified as benign.
Broader gene testing
Additional genetic testing beyond microarray is often recommended for pregnancies with a detected anomaly. Such testing includes:
- Gene panel: The ultrasound findings may suggest a particular condition, and condition-directed gene panels allow the examination of the multiple genes that are being considered. This test “reads” the DNA sequence that makes up the gene.
- Exome or genome sequencing: The genome is all of our DNA, and the “exome” is the part of the genome that creates specific proteins to help our bodies function, develop, and reproduce. This test sequences, or reads, many genes associated with the ultrasound findings.
- Disorder-specific testing: Not all conditions are due to a change in the gene sequence. Some arise in how the genes are turned on or off. Specific tests can check for these conditions.
Your genetic counselor will help you decide whether this testing is right for you and your family.