When selecting a sperm or egg donor, every intended parent has unique preferences—some may prioritize physical appearance, education, or ethnicity. However, from a genetic screening perspective, certain universal standards should be followed to help minimize the risk of passing on inherited conditions. Choosing a genetically compatible donor plays a vital role in safeguarding the health of your future child. This guide outlines essential considerations to help you make informed and medically sound choices.

🚫 Donors You Should Absolutely Avoid

One of the most critical principles in choosing a donor is to never select someone who carries the same recessive disease-causing gene mutation as one of the intended parents.

For example, if the intended father is a carrier of a specific autosomal recessive condition, you must not select an egg donor who carries the same mutation. The same applies to the intended mother and sperm donors.

Why is this important? If both parties carry the same recessive mutation, there is a 25% chance that the child will inherit both defective copies of the gene and develop the condition. While PGT-M (Preimplantation Genetic Testing for Monogenic Diseases) can be used to screen embryos for these mutations, the process is time-consuming, expensive, and may reduce the number of viable embryos.

Unlike the genetic risks between a couple, those involving a donor can be completely avoided—making this a non-negotiable rule in donor selection.

⚠️ Donors You Should Try to Avoid

Even if a donor does not share a mutation with you, there are some additional red flags to consider:

1. Donors Who Carry X-linked Genetic Disorders

X-linked disorders are caused by mutations in genes located on the X chromosome. Because males have only one X chromosome, if they inherit a faulty gene, they are likely to develop the disease. While male sperm donors with such disorders are unlikely to pass screening, female egg donors can unknowingly carry X-linked mutations without showing symptoms.

If a female carrier has a son, there’s a 50% chance he will be affected. Daughters have a 50% chance of becoming carriers. While not all X-linked disorders are severe, it’s best to avoid selecting egg donors known to carry them, especially when gender selection is not used.

2. Donors Who Carry Certain High-Risk Recessive Genes

Although most recessive carriers are healthy, some carriers may show mild symptoms, especially for certain genes. Examples include:

• Thalassemia (HBB or HBA1/HBA2 mutations): Carriers may have mild anemia or small red blood cells.

• Sickle Cell Trait (HbS mutation): Usually asymptomatic but may experience issues under low oxygen conditions.

• Hereditary Hemochromatosis (HFE mutation): Carriers may have slightly elevated iron levels.

• Cystic Fibrosis (CFTR mutation): Some carriers may show minor respiratory or digestive symptoms.

While these donors may be healthy overall, there is a 50% chance their child will be a carrier. This is not usually a major concern, but if both genetic parents pass on mutations, more serious conditions could result.

🧬 The More Comprehensive the Screening, the Better

An ideal sperm or egg donor should undergo expanded carrier screening that tests for hundreds of known genetic conditions. A few years ago, tests only covered 10 to 100 diseases. Today, many panels test for over 400 conditions, and this number continues to grow.

It’s important to understand: The more genes you screen, the more likely you are to find at least one mutation. That doesn’t mean the donor is “bad”—it just reflects how common carrier status is in the general population.

As a general rule:

Among equally qualified candidates, choose the donor who has undergone the most comprehensive screening and carries the fewest pathogenic mutations.

✅ Conclusion

From a genetic standpoint, selecting a sperm or egg donor is not just a personal decision—it’s a medical one. To minimize the risk of inherited diseases and ensure the healthiest possible outcome for your baby:

• Avoid donors who share a recessive mutation with either parent.

• Avoid donors who carry X-linked disorders, especially if choosing an egg donor.

• Be cautious with donors who carry high-impact recessive mutations—even if they seem healthy.

• Prefer donors who have undergone the most comprehensive genetic screening available.

These strategies can significantly reduce the chances of passing on genetic conditions and help give your child the best possible start in life.