The case came to light after two separate families contacted their fertility clinics when their children were diagnosed with cancer. Genetic testing confirmed that the children carried a rare mutation in the TP53 gene, which produces a protein that suppresses tumor growth.
Further investigation revealed the donor also carried the same mutation, which is associated with Li-Fraumeni syndrome—a rare and severe hereditary disorder that significantly increases the risk of developing cancer at a young age.
Subsequent testing uncovered 67 children born from this donor’s sperm, spread across 46 families in eight European countries. Of those, 23 children were found to carry the mutation, and ten have already developed cancer. All the affected children were born between 2008 and 2015, indicating the donor’s sperm was used over several years without centralized oversight.
Children carrying the TP53 mutation are now under strict medical surveillance, including full-body and brain MRIs, regular ultrasound screenings of the breasts and abdomen once they reach adulthood and frequent clinical exams. Doctors advise against radiation-based imaging methods like mammography or PET-CT scans, which may worsen conditions in patients with Li-Fraumeni syndrome.
Donor carried a germline mosaic mutation
The mutation was not recognized as cancer-causing in 2008 and therefore wasn't detected in routine donor screening. Only some of the donor’s sperm carried the mutation, suggesting a condition called germline mosaicism—where a genetic mutation is present in reproductive cells but not in the rest of the body.
This means a donor can unknowingly pass on serious hereditary diseases. A similar case was previously reported involving a donor who passed on a mutation causing neurofibromatosis type 1, which leads to skin tumors and pigment changes.
Under internal policies, the sperm bank that distributed the donor’s sperm limits each donor to 75 families—a figure not backed by any international law. Even after the mutation was discovered, the bank refused to disclose the total number of children born from the donor, raising concerns that more children could be affected but remain unaware and unsupervised.
Lack of international regulation fuels the risk
Regulatory gaps between countries make the problem worse. France limits each donor to 10 births, Germany to 15 and the UK to 10–12 families. But no such limits exist in many other countries and private sperm banks often operate with their own policies, allowing dozens of children to be born from a single donor—even across borders. Without a coordinated international system, many families remain unaware of shared genetic risks.
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The case highlights the potential dangers of cross-border sperm donation and the lack of regulatory safeguards. In addition to the risk of widespread transmission of hereditary diseases, the absence of oversight makes it difficult to trace affected children and ensure life-saving medical monitoring.
Medical authorities in France recommend choosing fertility treatments in countries where donations are strictly supervised by public health authorities. In France, donations must be anonymous, voluntary (unpaid) and subject to strict medical screening of both donor and recipient. Export and import of reproductive cells require special approval from the national bioethics agency.
Israel: No law on donor limits
Israel currently lacks binding legislation limiting the number of families per sperm donor. Guidelines issued by the Health Ministry and individual sperm banks serve as the only framework. Each bank sets its own limit to reduce the risk of unintentional familial relationships, such as half-siblings unknowingly marrying.
Dr. Eran Altman, Rabin Medical Center’s sperm bank director, told Ynet earlier this year, “The key question isn’t how many samples a donor gives but how many families conceive from a single donor. That’s the number that should be regulated.” He added that the lack of clear legislation has led to sperm banks creating their own rules and warned of longstanding government inaction.
For example, the sperm bank at Tel Aviv Sourasky Medical Center limits donors to 10 families. In contrast, many Israeli women turn to overseas banks—sometimes through local agents—where the limits range from 25 to 75 families or more.
Still, Israeli experts caution against using imported sperm. “Statistically, the risk of genetic issues is higher with foreign sperm,” said Dr. Yigal Madjar, director of Assuta Superm sperm bank. “A foreign donor could have 200 to 300 children worldwide. If a hereditary disease surfaces, it’ll be almost impossible to trace them all.”
By contrast, Altman noted that Israeli donors are identified to the Health Ministry, sign exclusivity agreements, and are barred from donating to multiple local banks—reducing the risk of duplication or fraud.
Although the Health Ministry has previously announced plans to cap each donor at 10 families and several private bills have been submitted to that effect, no law has been passed.
While this case remains rare, experts like Dr. Madjar warn it could happen again unless strict international regulations are adopted. They recommend legally capping the number of children per donor, requiring full transparency and coordination between countries and ensuring medical follow-up for all affected families.