One sperm donor fathered 200 children, passed on deadly mutation – it could easily happen again

Leicester: Around 200 children in several countries were conceived with sperm from a single donor who unknowingly carried a rare genetic mutation linked to early-onset cancers, it has been revealed. The consequences have been devastating. Several children have already died, and many families across Europe are now facing a risk they never expected.

The case has prompted urgent questions. How was one donor used so widely? Why did standard safeguards fail to identify a mutation that can have such severe consequences? And how did a system created to create families allow a tragedy of this scale?

When someone donates sperm or eggs, they are screened for a set of common inherited conditions before being accepted by a clinic. The exact process varies by country, and it has limitations. Screening depends heavily on accurate family history, yet many people have incomplete information about their relatives.

Some conditions emerge later in adulthood, which means a young donor may appear healthy. Clinics also focus primarily on established, higher frequency conditions rather than the vast number of rare variants that exist.

Ordinarily, donors complete a detailed questionnaire covering their medical background and their family’s health history. If the information suggests a possible inherited risk, the donor may be offered further testing or, more commonly, they may be declined.

More recently, clinics have begun to use expanded genetic screening. These tests can examine hundreds of genes linked to childhood or early adulthood conditions.

However, the technology is still developing and cannot detect every possible disease-causing variant. Many rare mutations are not part of routine panels, either because they have only recently been identified or because the evidence base is still small.

That context matters in this case. The donor had no family history of the condition and showed no symptoms. A person can carry a harmful mutation without being affected themselves, so nothing in their medical history raised concerns. The newer, broader screening was not used, but even if it had been, the variant is so rare that it may not have been included or detectable.

The donor provided sperm to the European Sperm Bank in Denmark for around 17 years. His donations were used to create roughly 200 children across multiple European countries, although experts say the true number could be higher.

This scale was possible because there is no international law limiting how widely donor sperm can be distributed. Many countries have rules on how many families can be created from a single donor.

The United Kingdom, for instance, permits no more than ten families. These limits, however, apply only within national borders. A donor can be used in several countries without any system to flag that the overall number has far exceeded what any one country would allow.

A recent unrelated case showed how extreme this can become. A different donor was found to have fathered around 1,000 children in several countries. There were no known health issues in that situation, but it revealed how donor use can expand rapidly without oversight.

The challenges in the current case are profound. Families are dealing with grief and uncertainty. Some have lost children. Others face a very high likelihood that their child will develop cancer before the age of 60, often in infancy or childhood.

There has been little public discussion about the sperm donor himself, although the emotional impact of learning these outcomes is likely to be significant.

Because the mutation was so rare, additional routine testing would probably not have prevented what happened. In truth, every person carries some genetic variants that remain undetected and harmless in everyday life.

There have been earlier examples of donors unknowingly passing on inherited conditions, such as cystic fibrosis or fragile X syndrome, but those cases typically involved far fewer families. What makes this case stand out is the sheer number of children affected.

For this reason, simply calling for more screening is unlikely to be the full answer. The more pressing issue is the lack of limits and monitoring on how many families can be created from one donor across borders.

In this case, families were created in several countries, and in some places, even the national limits were breached. Belgium, for example, permits only six families per donor, yet reports indicate that about 38 families were created.

What is needed is a robust system for tracking and tracing donor use both within and between countries. Without coordinated oversight, national limits are easily bypassed. Establishing international upper limits will be difficult and politically complex, but the conversation has to begin if further tragedies are to be prevented.

As more people use commercial DNA testing to find donor relatives, large networks of siblings connected across countries are becoming increasingly visible. The implications for those families are significant.

A coordinated global approach is overdue and would help prevent another case like this one, where families are left facing consequences they could never have foreseen.