Paternal Age: Risk of Offspring with Rare Disease
Researchers take a closer look at the paternal age effect that increases older fathers’ chances of having a child with a rare disease
Oxford scientists have for the first time been able to identify the origins of some severe disease-causing mutations within the testicles of healthy men. This discovery will help our understanding of how certain serious genetic disorders can occur in the offspring of healthy parents, who do not themselves have the genetic defect. The research is published in the journal PNAS.
For the Oxford team, it is just the latest phase in a research programme that has been running for over 20 years. In the 1990s Professor Andrew Wilkie and colleagues were investigating a condition called Apert syndrome that affects the development of the skull and limbs. Most children with Apert syndrome are born to unaffected parents and Professor Wilkie’s team showed that these cases are caused by new mutations (in a gene called FGFR2) that spontaneously arose as the father’s testes produced new sperm. Based on the prevailing knowledge of how spontaneous mutations arise, we would expect Apert syndrome to be extremely rare, but surprisingly cases occur up to 1,000 times more frequently than this.
To find out why this disease is more common than expected, Professor Anne Goriely compared sperm from fathers of children with and without Apert syndrome, and found that both groups had rare sperms with the mutation. She explained ‘the process that gives rise to Apert syndrome happens in every man, meaning any couple could have a child with Apert syndrome, regardless of the health of the parents. I also found that older men tended to produce more of these Apert mutations’. Professor Goriely also showed that normal men produce sperm with other mutations that cause lethal forms of dwarfism and other severe syndromes.
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