Preconception Screening Faq's
Preconception carrier screening is a screening test to determine carrier status for couples before achieving pregnancy and is aimed at predicting the likelihood of having a baby with an inherited genetic disorder.
A carrier is a person who is asymptomatic (has no symptoms) or, in some cases, can have only mild symptoms of a genetic condition. This is because they have one working copy of the gene and one non-working copy of the gene. Carriers are typically unaffected and do not have family history, but can pass on the non-working gene to their offspring.
Carrier screening is a simple process that involves testing DNA through a sample of blood or saliva.
Ideally, anyone considering having a baby should get carrier screening before pregnancy, i.e. preconception. Carrier screening is often times done during pregnancy as well. Having said that, preconception carrier screening allows you the benefit of time and a broader range of options to make reproductive decisions.
Because most carriers are healthy and typically do not have any family history, couples who want to be proactive about planning a family should consider carrier screening. The presence of family history can be a red flag that warrants carrier screening. A genetic counselor will evaluate family history and provide risk assessment after asking pointed questions about your health and the health of your family. You are at increased risk if:
- - You have been diagnosed with a genetic condition
- - You have a previous child with a genetic condition
- - You have family history of a genetic condition
- - Your ethnicity is known to have a high rate of carriers of certain genetic conditions
People of certain ethnicities have a greater chance of being carriers and passing on certain genetic conditions. Therefore, ethnicity based carrier screening is the minimum that MUST be offered to certain groups. Common genetic conditions for a few specific ethnicities are:
- - Caucasians: Cystic Fibrosis
- - - Ashkenazi Jewish heritage: Tay-Sach, Familial Dysautonomia, Canavan disease, Cystic Fibrosis, Bloom Syndrome, Niemann-Pick Disease, Fanconi Anemia, Mucolipidosis IV, and Gaucher Disease
- - African heritage: Thalassemias and Sickle Cell Disease
- - Mediterraneans: Thalassemias and Sickle Cell Disease
- - Southeast Asians (Indians): Thalassemias and Sickle Cell Disease
A genetic counselor will give you an estimate of your chance of having a child with a genetic condition. The vast majority of conditions screened for during carrier screening are autosomal recessive and if both parents are carriers for the same condition, there is a 25% chance that the child will have the disorder, a 50% chance that the child will be an unaffected carrier (just like the carrier parents), and a 25% chance of being a non carrier. If only one parent is a carrier, there is a 0% chance of having a baby with the condition, and 50% chance that the child will be an unaffected carrier (like the carrier parent).
If you and your spouse are both identified to be carriers of the same genetic condition, there are reproductive options that you may consider. Some carrier couples choose to proceed with pregnancy and consider the option prenatal testing; some couples choose in vitro fertilization (IVF) with either donor eggs or donor sperm to achieve pregnancy, some couples choose to get Preimplantation Genetic Diagnosis (PGD), and some choose not to become pregnant.