Your Donor Fits You But Do Their Genes?

By Shannon Wieloch — January 22, 2018

2 min read

You’ve decided to use a donor. No matter what brought you to this point, there are a lot of factors that go into picking the right egg or sperm donor for you. As a genetic counselor, this is something I talk to many patients about, so I’ve seen firsthand what issues recipients consider.

Typically, future parents, of course, want their children to look like them, so maybe you want to make sure your donor has green eyes or black hair like your partner. Then there are the broader categories of ethnicity, religion, hobbies, and education.

To some, from where the donor graduated college is crucial. To others, whether the donor is musically inclined might be more important. We all would want the “best of the best”, but no one is perfect, so you have to decide which attributes are most important to you.

When researching donors, you will often have access to medical information that has been collected and I’m here to tell you, this information is can be key. Both egg and sperm donors are required to go through a litany of screenings including testing for communicable diseases, a psychological assessment, and a detailed medical history. Many donors are also required to go through expanded carrier screening, which is a genetic test designed to assess whether someone is at increased risk of passing a genetic condition on to the next generation. This testing is incredibly vital because the donor’s genes could impact the health of your future children.

This is where I find many of my patients get hung up. Because, for the  majority of them, their dream donor, with the big brown eyes, olive complexion, and 4.0 GPA from a top school may be, dare I say it . . . identified to be a carrier of . . . something.

So how much do those results matter? Well, as a genetic counselor at a carrier screening laboratory, I can say that they could be super insightful. But a donor’s results may not be a reason to cast aside said donor and start your search anew. Here are a few things to consider after receiving your donor’s results:

1.) For autosomal recessive conditions, such as cystic fibrosis or Tay Sachs disease, both egg and sperm must carry a disease-causing variant for the same condition in order for a pregnancy to be at an increased risk of being affected. If the donor is a carrier, but the recipient is not, then the risk to have an affected child is reduced. The specific risk remaining after testing depends on a number of factors, including ethnicity of the recipient and the sensitivity of the technology used for the carrier screening. If you are comfortable with the residual reproductive risk, you may not feel the need to search for a new donor.

Of note, this does not hold true for female carriers of X-linked recessive conditions, like Fragile X syndrome or Duchenne muscular dystrophy. If a woman who intends to be an egg donor is found to be a carrier of an X-linked recessive condition, then the risk of having an affected male child is 50%, which often excludes that woman from being a donor.

2.) Carriers of recessive conditions are generally healthy. Thus, if your donor does pass their variant on, as long as the kiddo gets a working copy of that gene from you, your new bundle of joy will also be a carrier but should typically have no ill effects. In order to determine potential effects of a positive carrier status, take the time to speak with a genetic counselor to determine what being a carrier of a given condition may look like.

3.) How impactful is the condition for which your donor is a carrier? For some recipients, donors who are carriers of a condition associated with intellectual disabilities would be disqualified. For others, however, having a child with a condition that would require surgical intervention would be the determining factor. Most conditions are highly variable, not only in terms of age of onset but also clinical severity. Again, a genetic counselor can help by discussing the condition, the risk to have an affected pregnancy, and the testing options available to further refine this risk.

Obtaining, and understanding, this information is powerful for everyone: you, your children, and maybe even one day, your children’s children! Information that, currently, is not available through any other means than carrier screening.

Choosing a donor can, in a sense, be like picking out baby names. At first, the process is exciting, but it can quickly turn into an arduous endeavor. Don’t let carrier screening, or rather the results of it, dampen the process. Instead, consider how this information relates to your family building odyssey, so you are better equipped to make the best decision for you.