A new study finds certain genetic abnormalities in a man's chromosomes appear to be linked to intellectual disabilities in his off-spring, especially if he fathered them late in life.
These abnormalities are caused by what are called copy number variants such as missing or repeated DNA sequences.
It is commonly known that the risk of birth defects, such as Down syndrome, increases with maternal age, but this study shows an increased paternal age is also an important factor.
