It is estimated that all human beings are carriers of multiple genetic conditions, even without a family history or awareness of their carrier status prior to a screening. The intention of a genetic carrier screening test is to identify if you carry a gene with a change, or variant, that can impact offspring. When performed before conceiving, genetic carrier screening can provide actionable information and opportunity to pursue alternative reproductive options.
Generally, genetic carrier screening tests for recessive genes that cause moderate or severe childhood diseases, lead to a shorter life expectancy, cause disability, and/or have no treatment options. It is important to understand intended parents’ and donor’s specific results in order to decide what to do with the information you learn.
It can be surprising to learn that it is actually more common to have a positive (“abnormal”) carrier screen than to have a negative (“normal”) test result. Depending on the number of genes tested and how thorough the technology used by the particular lab is, about 70-80% of healthy people will test positive as a carrier of one or more recessive diseases.
The majority of people who are found to be a carrier of a recessive disease are surprised by their results and may have no family history of the condition they carry. Because positive results are so frequent, the need to learn about the combination of your and your prospective egg donor’s results together is a very typical step of the donor egg process and should always be done before the donor’s egg retrieval cycle is started – and ideally, prior to the match being official.
What happens if you are a carrier?
The American College of Obstetricians and Gynecologists defines genetic disorders and the role of carrier as such:
“For some genetic disorders, it takes two genes for a person to have the disorder. A carrier is a person who has only one gene for a disorder. Carriers usually do not have symptoms or have only mild symptoms. They often do not know that they have a gene for a disorder.”
In other words – being a carrier doesn’t mean that you are at risk for any diseases or that your offspring automatically will be affected. Genes are inherited in pairs: one from the mother (egg provider) and one from the father (sperm provider). A genetic carrier is someone who has mutation, in only one copy of a gene — meaning the carrier has inherited a recessive allele for the mutation. Since the other copy of the gene is working properly, the carrier does not develop or have symptoms of the disease.
Donors who have 1 or more positive genes on their tests are not ineligible or disqualified, it simply allows us to narrow down potential intended recipients.
Why donors and intended parents cannot match if they are both carriers for the same gene
If the donor and recipients are carriers of the same condition, then there is a 25% chance for the pregnancy or child to inherit both recessive variants and be affected by the condition. In most cases, such a match is discouraged. This is why genetic counseling is a critical step for intended parents to understand possible outcomes and risks – ultimately helping them determine whether the match is appropriate or not. All Signature Donors and Intended Parents undergo genetic counseling.
Genetic Carrier Screening FAQs
What is genetic carrier screening, and why is it important in egg donation?
Genetic carrier screening is a test used to identify whether someone carries a gene for certain inherited conditions, even if they don’t show symptoms. In egg donation, this helps ensure that the donor’s genes won’t combine with the recipient’s to increase risk of passing on a genetic disorder.
What types of conditions are screened during the process?
Commonly screened conditions include cystic fibrosis, Tay-Sachs disease, spinal muscular atrophy, sickle cell anemia, and over 100 other inherited disorders. The panel may vary depending on ethnic background and family history.
Does being a carrier mean the donor has a genetic disease?
No – being a carrier means the donor has one copy of a gene mutation, but they do not have the disease. However, if both the donor and intended parent are carriers for the same condition, there’s a risk of passing it on to the child.
Is carrier screening required for all egg donors?
Yes – at Signature Donors, genetic carrier screening is a standard part of the screening process to ensure the health and safety of any future child, as well as to inform intended parents of any potential risks.
Can donors still be accepted if they are carriers?
Possibly. If a donor is a carrier for a condition, they may still be eligible depending on the recipient’s genetic status and preferences. In such cases, genetic counselors help interpret the results and assess risk.
