Can Genetics Help?
Preconception genetic carrier screening is offered to patients before becoming pregnant to determine the chances of having a child with a genetic disorder. Many people are carriers of genetic mutations, but have no signs or symptoms of the disorder because a carrier still has one normal gene in addition to the abnormal, mutated gene. You may be a carrier for a serious genetic disease (such as cystic fibrosis), but never know without genetic screening.
If two people carry the same genetic mutation and have a child together, there is a high risk that they will have a child with a genetic disorder. The majority of children born with a genetic condition have no family history of that disease because carriers are typically unaware that they have a genetic mutation.
If both parents are carriers, there is a 25% chance that the child will get the abnormal gene from each parent and will have the disorder. There is a 50% chance that the child will be a carrier of the disorder—just like the carrier parent. There is a 25% chance that the child will only inherit the normal genes. If only one parent is a carrier, there is a 50% chance that the child will be a carrier of the disorder and a 0% chance that the child will have the disorder.
People are at increased risk of being a carrier of a genetic mutation if they already have a child with a genetic disorder, if there is a family history of a genetic disorder, or if they belong to a certain ethnic group that has a high rate of certain genetic disorders.
Ethnic groups with an increased risk of genetic disorders include:
- Non-Hispanic white individuals should be offered cystic fibrosis carrier screening.
- People of Eastern European Jewish descent (Ashkenazi Jews) should be offered screening for Tay–Sachs disease, Canavan disease, familial dysautonomia, and cystic fibrosis. Individuals can ask about screening for other disorders. Carrier screening is available for mucolipidosis IV, Niemann–Pick disease type A, Fanconi anemia group C, Bloom syndrome, and Gaucher disease.
- People of African, Mediterranean, and Southeast Asian heritage should be offered screening for thalassemias and sickle cell disease.
Though targeted genetic screening can be performed, many resources, such as Recombine, now offer carrier screening for over 300 genetic mutations in one simple test. These tests can be viewed as a way to provide a couple with the most information before they start treatment or add to their family.
In addition to the genetic screening, patients will receive genetic counseling to discuss the results. If a patient and partner learn that they are both carriers of a genetic mutation, there are several options:
- They can proceed with becoming pregnant, then undergo prenatal diagnosis with amniocentesis or chorionic villus sampling to see if the baby is affected.
- They could also undergo in vitro fertilization with preimplantation genetic diagnosis to identify the affected embryos and avoid using those to become pregnant. Recombine will assist with the costs of such treatment in the event a couple is identified as being carriers of the same mutation.
- Couples also have the option of using donor sperm or donor eggs that do not have the mutation so that their child will not be affected.