Older dads, greater risk?

27 October 2009

A rare form of testicular tumour could help to explain why certain genetic diseases are more common in the children of older fathers.

The link between the genetic conditions and the tumour are the germ cells that produce sperm. If certain genetic mutations arise in these cells, they can be passed on to offspring and cause conditions including achondroplasia and Apert, Noonan and Costello syndromes. As these mutations happen to be in genes that are involved in controlling cell multiplication, they also encourage the mutant cells to divide and multiply, causing tumours to develop.

When these mutant cells divide, they copy the mutation to each daughter cell. So, the number of mutant cells - and hence the number of mutant sperm produced - increases with age, raising the risk that older fathers will have affected children.

Professor Andrew Wilkie from the University of Oxford, who led the study, explains: "We think most men develop these tiny clumps of mutant cells in their testicles as they age. They are rather like moles in the skin, usually harmless in themselves. But by being located in the testicle, they also make sperm - causing children to be born with a variety of serious conditions."

Image: Father and son with a basketball. Credit: Reddoch Graphics/iStockphoto

Reference

Goriely A et al. Activating mutations in FGFR3 and HRAS reveal a shared genetic origin for congenital disorders and testicular tumors. Nat Genet 2009;41(11):1247-52.