Research links older dads to genetic diseases

Several rare genetic disorders, including dwarfism, are more prevalent among the children of older fathers.

University of Copenhagen and University of Oxford researchers have discovered a surprising genetic link between the formation of benign testicular tumours and such genetic diseases, writes the British news website timesonline.co.uk.

Mutant sperm

Abnormal testicular cells in these tumours, known as Spermatocytic seminomas, produce sperm carrying mutant genes that cause inherited diseases, research at the Copenhagen University Hospital has shown.

»We think most men develop these tiny clumps of mutant cells in their testicles as they age,« says Professor Andrew Wilkie of the University of Oxford, who led the research.

»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,« he adds.

Tip of the iceberg

The findings offer important new insights into the origin of several rare genetic disorders, including a cause of dwarfism called achondroplasia.

The implications of this research could also lead to inisights into the genetic causes of more common conditions such as autism, schizophrenia and breast cancer.

»What we have seen so far may just be the tip of a large iceberg of mildly harmful mutations being introduced into our genome. These mutations would be too weak and too rare to be picked up by our current technology, but their sheer number would have a cumulative effect, leading to disease,« explains Professor Wilkie.

Details of the research are published in the journal Nature Genetics.

The research team is now planning to investigate whether testicular abnormalities might be linked to conditions such as autism and schizophrenia.

Implications for older dads

The results will help doctors to explain to parents why children have developed these disorders, and to advise them about the risks of having further children.

»The major implication is for older fathers,« says Andrew Wilkie.

»We already knew that men in their 50s have a risk of having children with various individually rare genetic disorders — achondroplasia is a well known one — about tenfold higher than men in their early 20s.«

luci@adm.ku.dk