Why older men risk fathering autistic children

Why older men risk fathering autistic children

By Steve Connor
Monday October 26 2009
Scientists may have found why older men are at greater risk of fathering a child with serious health problems.
Researchers have found that older men are more likely to harbour a rare testicular tumour which may also cause genetic mutations in the DNA of their children, who inherit faults such as congenital deformities, autism, or schizophrenia.
CLUMPS
Professor Andrew Wilkie, of Oxford University, said that clumps of tumour-producing cells form in the testicular tissue which produces the "germ cells" that give rise to sperm.
"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," Prof Wilkie said.
"But by being located in the testicle, they also make sperm, causing children to be born with a variety of serious conditions."
Professor Wilkie said that the latest study, published in the journal Nature Genetics, could help to explain the origin of several serious conditions affecting children, including achondroplasia, which is commonly known as dwarfism, as well as stillbirths.
The work may also help scientists to find the many genes that are involved in common diseases where there is a strong genetic component, such as autism and schizophrenia.
Until recently, it was assumed that only women had to worry about having children in later life but a number of studies in the past decade have shown that as the quality of a man's sperm decreases with age, the risk of him fathering a child with serious health problems increases.
The overall risk for an older father of having a child with a birth defect is estimated to be about 4pc, compared with a "background" risk of about 3pc.
ILLNESS
One study carried out in Israel suggested that men who became fathers at the age of 40 or older were nearly six times as likely to have a child with autism compared with men younger than 30 when they became fathers.
Research into schizophrenia suggests that the risk of the illness doubled among the children of older fathers compared with the children of men who became fathers in their 20s.
hnews@herald.ie
- Steve Connor