Transgenerational epigenetic information through the sperm: Sperm cells not just merely supply half of the genome for new life; they also seem to transmit additional information via epigenetic modifications

The biological cause for the increase in Autism Spectrum Disorder may be fathers’ older age and the epigenetic marks it leaves on sperm cells. Subject Categories: Chromatin, Epigenetics, Genomics & Functional Genomics, Development & Differentiation, Ecology

COVID‐19 is not the only pandemic that is affecting an increasing number of people; autism spectrum disorder (ASD) is another ongoing pandemic that has attracted much less attention despite the fact that its prevalence is rapidly increasing. Between 1975 and 2009, the frequency of ASD in the United States increased from 1/5,000 to 1/110, and the US Centers for Disease Control and Prevention recently reported an incidence as high as 1/54 (see “Further reading”). This is not confined to the United States of course but the same trend can be observed in other countries as well. One possible explanation for this dramatic increase in ASD is the change of diagnostic criteria. These were established in the 1980s and have since been expanded to include milder forms of autism. Along with more public awareness of ASD and more cases being recognized as such, this would explain, at least in part, the increasing number of affected children, but social and diagnostic factors are not sufficient to explain the rise of ASD: there must also be biological factors at play. Indeed, various epidemiological studies suggest that the age of the parents, in particular the father’s age, is an important risk factor.The age at childbirth is related to socioeconomic issues: longer education or higher costs for raising and educating children correlate with older parental age. In addition, assisted reproductive technologies are further increasing the age of birth as this helps women to delay motherhood until into their late 30s or even 40s. However, as both reproductive capacity and the quality of germline cells decline with age, older age at childbirth is associated with lower pregnancy rates, increased risk of miscarriage, and higher risk of various diseases and disorders for the children.