Men's age impacts hereditary mutations in children

It seems Dad’s age at conception-not Mom’s-may be the primary predictor of whether a child develops a condition such as autism or schizophrenia.

A new study in Nature shows that as men age, the number of new mutations in their sperm-and the likelihood that some of the errors will be passed to offspring-increases. As a result, the worldwide trend of men starting families later in life may be part of the reason why conditions such as autism are on the rise.

Researchers sequenced the genomes of 78 Icelandic families with a child diagnosed with autism or schizophrenia and found that for every year a man ages, 2 more new gene mutations appear in his offspring. They calculated that the number doubles every 16.5 years from puberty onward, meaning that 36-year-old men pass on twice as many mutations to their children as do 20-year-olds. At what age this trend becomes problematic, however, is impossible to know because many other factors affect children’s health and many of the mutations are harmless.

As women age, the researchers note, they are at greater risk of having a child with Down syndrome or other rare chromosomal abnormalities, yet men transmit about 4 times more new gene mutations to children. Experts think this disparity may have something to do with the fact that men continually make new sperm with the help of dividing precursor cells, which acquire new mutations with every division.

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