When selecting donor eggs or sperm , it can be helpful to consider the setting of the donor banks which tend towards a competitive international market. This in turn can make the search for a potential donor challenging to navigate and research as each donor bank may present information differently. Generally the main considerations are:
- Physical/personal characteristics
- Family health history
- Genetic testing
- Sample options
Physical/personal characteristics
This is usually the easiest information to find. Generally, information regarding eye colour, hair colour, build, and height are headlined on a donor profile. Ethnicity is usually self-reported by the donor or sometimes more accurately described based on DNA ancestry testing.
A pen portrait essay provides the donor with the opportunity to express their motivations for donation as well as share personal attributes. Personality profiles may also be provided by the donor bank, which can sometimes include more formal psychometric testing.
Family medical history
Whenever a donor is recruited to a donor bank, a two-generational family heath history will be elicited from the donor by the clinical team. This includes checking for a list of health conditions and if they are noted in the donor’s family how the condition impacted the family member and any treatment received. For some family health histories donors may be excluded from a donation programme, other donors may continue with their family health history shared with recipients. When health conditions are due to multiple genetic and environmental factors that are difficult to predict, for example type 2 diabetes, a recipient with a family history of type 2 diabetes may feel more comfortable selecting a donor where there is no family history or the same health condition.
Viral and bacterial screening
Only donors who screen negative for HIV, hepatitis, B and C, chlamydia gonorrhoea and syphilis are usually recruited. The donors should be screened regularly throughout their participation in the donation programme so that eggs and sperm have evidence of negative screening for the donor before and after freezing.
Genetic testing
Karyotype is a test that looks at the number of chromosomes a person has, making sure the correct number and arrangement are seen. If a karyotype test shows a significant finding a donor will not be recruited.
Carrier screening – Donor banks screen donors for a variable number of recessive genetic conditions. It can be daunting but some information to help what a carrier status means, which is explained using the following Q&A
Q. What is carrier screening?
A: Genes are the instructions in our DNA needed for healthy development and functioning of our bodies. Typically we inherit two copies of each gene, one from the egg and one from the sperm. Every person has millions of genetic differences, most of which do not cause disease or impact our health. However, some changes can prevent a gene from working.
Carriers have one altered gene and one functioning gene and are therefore healthy, however disease can occur in children if the same altered genes are inherited from the sperm and the egg. This is called autosomal recessive inheritance. An example a recessive condition you may be familiar with is cystic fibrosis.
Q: Has a donor been screened for recessive conditions?
A: In the UK, current guidelines require donors to be screened for cystic fibrosis as a minimum, as this is the most common condition carried in the Northern European population. Non-European donors must also be screened for conditions that are known to be more common in their ancestral population.
Advances in genetic testing have made it possible to screen for multiple recessive conditions simultaneously, called carrier screening. Many sperm and egg donor banks routinely perform carrier screening; some screen for a few conditions, and some screen for several hundred (expanded carrier screening). However, the testing does not test for all genetic diseases and may not be 100% accurate, meaning there is a small chance that a donor could still be a carrier even if the test result is negative.
You can ask the donor bank what recessive conditions the donor has been screened for; if a donor has had carrier screening and is a known carrier, this should be shared with you.
Q: What does it mean for a recipient if a donor is a carrier of a recessive condition?
A: Most people are carriers of recessive genetic conditions. Being a carrier generally has no impact on a person’s health. However, there could be a risk for a child if both the donor and recipient are carriers of the same condition.
This risk depends on how commonly a carrier status occurs in the population. For example, disease-causing changes in the cystic fibrosis gene are thought to be carried by about 1 in 25-30 people in the Northern European population. If a donor and recipient are both carriers, there would be a 1 in 4 or 25% that a child would be affected. Your personal risk will vary depending on the condition the donor is a carrier for and your genetic ancestry.
Most recipients do not know if they are a carrier for recessive conditions. A reproductive risk for using a carrier donor can be estimated using current population-based data that give the chances of a person being a carrier; this is called the carrier frequency. For example, if the carrier frequency of a condition carried by a donor is 1 in 25, the risk of having a child with the condition would be 1% or 1 in 100. For a carrier frequency of 1 in 100, the risk of having a child with the condition would be 0.25% or 1 in 250. To put this risk in context, the background risk of congenital anomalies or disability for all pregnancies is approximately 3-5%.
Q: Can I choose a donor who is a carrier of a recessive condition for my treatment?
A: There are plenty of considerations for choosing a donor. If a donor is a carrier of a recessive condition(s), this usually should not be a barrier to use in treatment. Often a donor bank may ask you to sign a consent to say you have been given sufficient information about using a donor with a specific carrier status. Your clinic or donor bank should be able to support you with this form.
If you are choosing a donor who is a carrier of a condition with this risk, it is recommend that you speak with a suitably qualified person to be counselled on the implications including the option of genetic testing for yourself. Genetic counselling or professional advice is not mandatory as there are no recommendations for such screening for ‘natural conceptions’. However, some people may feel comfortable understanding their level of personal risk to proceed with using a donor, while others may prefer to have carrier screening to see if they are a carrier match where there would be a 1 in 4 or 25% risk for a child. Policies may vary between fertility clinics and donor banks. Everyone’s acceptance of risk is different, and it may be helpful to speak with a suitably qualified person with knowledge of genetics and inheritance to discuss this.
Direct to consumer carrier screen kits purchased on the internet often do not test genes in sufficient detail for carrier matching.
If you know your donor is a carrier of a particular recessive condition(s) a child will have a 50% chance of inheriting the altered gene and being a carrier which although will not impact their health may be useful for them to know when they are planning families of their own in the future.
Sample Options and Quantity
Donor eggs are usually sold in ‘batches’ of 4, 6, 8 or more, and egg banks may offer different thaw and embryo development guarantees. It is important that you and the clinic are clear about what your particular guarantee may be and that it is possible to access the guarantee with your treatment plan.
Donor sperm is often packaged in portions where samples with a high number of motile sperm will be a higher price. Sperm samples for intrauterine insemination will have more motile sperm than those sold for IVF,(where the egg and sperm are placed together in a dish in the laboratory to fertilise) and IVF samples will have more motile sperm than samples sold for ICSI (where a single sperm is injected in the egg in the laboratory).
Some donor banks give a minimum quantity of motile sperm for a vial of a certain type. You may also see a MOT value which stands for the number of motile sperm per millilitre, the higher the MOT the more expensive the samples. Another option regarding the samples is whether they are washed or unwashed. Most assisted reproductive clinics wash the sperm for use in treatment, putting the sperm on a density gradient to gather all motile sperm together for higher concentration in a small volume, so it usually not necessary to buy washed samples.
Depending on your treatment, a higher or lower number of motile sperm may be required so check with the clinic which sample type and how vials or straws is recommended to purchase.
Family limits /donor anonymity
There’s a 10 family limit in the UK, however each country may have its own local regulations about how many families each donor can have. Currently there is no global limit or monitoring of family numbers although donors are asked to declare they donated in other clinics and or other countries.
In the UK donors are registered with the IVF clinic regulator the Human Fertilisation and Embryology authority. This is so a child at the age of 18 can access identifying information about a donor. Any donors imported to the UK from abroad also have to be registered. In other countries donors may be anonymous with no information available apart from that provided at the time of donation.
The availability of DNA ancestry testing does create the opportunity for donors to be traced if the donor or their family members have completed the same ancestry test.
Resources
- The donor conception network UK https://www.dcnetwork.org/
- https://www.hfea.gov.uk/donation/
- https://www.eshre.eu/Guidelines-and-Legal/Guidelines/Information-provision-in-donation
- https://www.progress.org.uk/bionews/