Family Planning: Experts Recommend Genetic Testing For Couples Before Conception
Couples eager to start a family often include genetic testing and carrier screenings in their preconception plans to improve their chances of having a healthy baby. Perhaps one person has a family history of a particular genetic disorder and wants to know if she and her partner are at risk for giving birth to children with specific genetic disorders.
They both understand that genetic screening may confirm their carrier status for that particular disorder, enabling them to make choices based on today’s many options for starting a family.
The terms genetic screening and genetic testing are often used during pregnancy, and their meanings are frequently interchanged. They both use laboratory tests to identify the presence of specific changes in genes that may cause genetic disorders. Genetic testing, however, is usually offered to people already suspected to be at high risk for a particular genetic disorder because of a prior personal or family history. Genetic testing is also sometimes used to help doctors decide on the best medicine or treatment for specific individuals.
Carrier screening is used to find people who carry a change in a gene linked to a disease. They usually show no signs of the disease themselves but have the ability to pass on the gene change to their children who may become carriers.
Couples do genetic testing to look for changes in genes that cause them not to work properly. If a baby inherits the same non-working gene from both parents, that can lead to certain genetic diseases. These are recessive disorders, meaning that each parent needs to pass a non-working gene to the baby for the child to be affected. But, if the mother screens positive for a genetic abnormality and the father doesn’t, their child isn’t likely to inherit the condition. Even if both mother and father screen positive, there’s only a 25 percent chance with each pregnancy that their baby will have the disease.
“Genetic screening is important for all couples preparing to start a family,” says Jerry Feldman, M.D., Ph.D., professor, at the Center for Molecular Medicine and Genetics, Pediatrics and Pathology at Wayne State University School of Medicine. “It is particularly important for the Ashkenazic Jewish population because they are at higher risk than the general population for many specific genetic disorders. Other racial and ethnic groups have different genetic diseases that are more common in their groups.”
The Ashkenazi Jewish Genetic Panel, AJGP, covers those diseases that occur more frequently in people of Eastern European (Ashkenazi) Jewish descent rather than in the general population. The AJGP test tells parents if they have an increased chance of having a child with certain genetic diseases.
“During the past several years and primarily as the result of newer technologies, the AJGP has been expanded by some laboratories to include 80-plus disorders,” Feldman says. “Different labs may have different tests in the panel they use. There’s no such thing as a standard panel anymore.”
“In addition, the trend now is toward pan-ethnic screening, a more comprehensive screening panel that includes common genetic disorders for the Ashkenazic population as well as for other ethnic groups and minorities,” he says. “New technologies make it viable to offer carrier screening for a large number of recessive conditions that affect people of many different backgrounds.”
Again, those laboratories offering pan-ethnic screening have different disease and mutation panels that make genetic counseling helpful when one or both members of the couple have abnormal screening results.
“We have about 20,000 genes in every cell of our body,” Feldman explains. “Our genes come in pairs — one copy from our mother and the other copy from our father. When a given gene has an error in it, it doesn’t work properly and can’t do its job. We call this a mutation.”
Genetic screenings are a proven method to decrease the prevalence of genetic diseases. For example, Tay-Sachs disease (TSD) carrier screening, initiated in the 1970s, has reduced the birth-rate of Ashkenazi Jews with TSD worldwide by 90 percent.
“Once it’s known whether both partners are carriers for a specific Jewish genetic disease, the couple can then explore ways in which to have a baby born without that genetic condition,” Feldman says. “Some of these options include sperm or egg donation, in-vitro fertilization(IVF) with pre-implantation genetic screening and adoption. The couple may also choose not to have children or may choose to have prenatal testing to determine if the fetus is affected with that disorder.”
Preimplantation Genetic Diagnosis (PGD) is a procedure used prior to implantation to help identify genetic diseases in embryos created through in-vitro fertilization so that the specific disorder is not passed on to a child. Following the normal process of in-vitro fertilization that includes egg retrieval and fertilization in a lab, one or two cells are removed from the embryo and evaluated to determine if a mutation is present. Only those embryos found to be free of specific genetic problems are placed back in the uterus and implantation is attempted. Embryos free of those specific genetic changes can also be frozen for possible later use.
“One of the major benefits is that the procedure enables couples to give birth to biological children without having to be faced with that 25 percent risk of a specific genetic disorder,” Feldman says. “More common, however, are those requests we receive for genetic testing from women who are already pregnant. Their choices of what to do next following the screening are more limited because PGD is not an option for that current pregnancy.”
It is recommended that those seeking more information about genetic screening and options should consult their insurance carrier regarding coverage for costs prior to testing.
By Ruthan Brodsky | Contributing Writer
JScreen Program Screens For Jewish Genetic Diseases
The JScreen genetics screening program employs an at-home education and carrier screening program for Jewish genetic diseases. It is a national nonprofit effort based out of Emory University’s Department of Human Genetics in Atlanta, in which testing is performed by a certified laboratory and test results are reviewed and reported to participants by genetic counselors.
The kit can be used to test carrier status for more than 100 genetic conditions, many of which are most common in people with Ashkenazi, Sephardi and Mizrahi ancestry, including Tay-Sachs disease, Familial Dysautonomia and cystic fibrosis.
“Screening is very relevant for anyone considering having children, whether they are currently single, dating or married,” says Hillary Kener, assistant director of national outreach. “By requesting a kit online at $149, the kit is shipped to an individual’s home where they provide a saliva sample and send it back using the prepaid shipping package. In approximately three weeks, the person being tested is contacted by a licensed genetic counselor from JScreen to discuss the results.”
To learn more or to request a kit, visit www.JScreen.org.