December 10, 2025

expert reaction to sperm donor passing on TP53 mutation

Scientists comment on a sperm donor carrying a cancer causing gene mutation used to conceive children.

Prof Clare Turnbull, professor of cancer genetics at The Institute of Cancer Research, London, said:

“This represents a highly unfortunate coincidence of two exceptionally unusual events: that the donor’s sperm carry mutations for an extremely rare genetic condition affecting fewer than 1 in 10,000 people and that his sperm has been used in the conception of such an extraordinarily large number of children.

“Li Fraumeni syndrome is a devastating diagnosis to impart to a family.  There is a very high risk of cancer throughout the lifetime.  And, unlike most cancer genetic susceptibility syndromes we encounter in clinic such as Lynch syndrome or that caused by the BRCA-genes for which the cancers are adult-onset, inherited mutations (pathogenic variants) in TP53 are associated with a sizeable risk of childhood-onset cancers.

“The TP53 mutation (pathogenic variant) was not present throughout the donor’s body tissues, meaning he had not inherited it.  The mutation would appear to have arisen in the testes but to have multiplied rapidly to affect a sizeable proportion of the spermatozoa, which have then been used for donation.

“This would potentially appear to be a demonstration of selfish spermatogonial selection, whereby a mutation can give the spermatogonial cells a growth advantage, allowing them to outcompete normal spermatogonia.”

Prof Jackson C Kirkman-Brown, Theme Lead – Reproductive & Maternal Health, School of Medical Sciences, College of Medicine & Health, The University of Birmingham, said:

“Screening for something de-novo in testis will never work on blood. Each sperm in an ejaculate is slightly different so screening these is also not simple – though if a child is born with a condition the screening sperm approach can be used to tell if a risk like this exists.

“In the end the issue here is around family limits and extended un-monitored use. 

“ESHRE are currently in the final stages of drafting a position on international family limits in donation. This is expected to be released formally in spring and is hoped to guide international legislation.”

Peter Thompson, Chief Executive of the HFEA, said: 

“We can confirm that the Danish Patient Safety Authority has informed us that a very small number of UK women have been treated in Danish Fertility clinics with this sperm donor. We understand that they have been told about the donor by the Danish clinic at which they were treated. As the UK regulator, we only collect or hold information about treatment which takes place in the UK. As the treatment took place at Danish clinics, further enquiries should be directed to the competent authority in Denmark.”

Declared interests

Prof Clare Turnbull: Professor Turnbull is a member of the National Screening Committee Research and Methodology Group

Prof Jackson C Kirkman-Brown: “Sitting on the ESHRE ethics committee”

For all other experts, no reply to our request for DOIs was received.