The ends of our chromosomes have little caps called telomeres that keep our DNA from degrading as our cells divide. Telomere length is partly determined by genetics. However, telomeres also shorten as we age and as a result of health conditions, including stress—as in institutionalized children in Romania and women caring for children with chronic illnesses.
An intriguing new study in the July Journal of the American Academy of Child and Adolescent Psychiatry finds shortened telomeres not just in children with autism (confirming a recent study from China) but also in their infant siblings and their mothers. An effect was also seen in fathers, but it didn’t reach statistical significance.
The study was relatively small (86 families had a child with autism, 118 did not) and needs to be replicated to confirm that the effect is real. But lead investigator Charles Nelson, PhD, of the Laboratories of Cognitive Neuroscience at Boston Children’s Hospital, thinks that shortened telomeres may help explain his and others’ observations that infant siblings of children with autism are at heightened risk for autism themselves.
Autism places huge psychological stress on children with autism and their mothers. Are younger siblings also feeling that stress, or are they simply sharing a family genetic tendency toward shorter telomeres? Or are the same genetic factors involved in autism also shortening telomeres? Some gene variants linked to autism, for example, are associated with increased oxidative stress, which erodes telomeres; others regulate DNA repair.
“Although additional research will be required to tease apart these variables, it seems that there is a potential biological cost to family members raising an infant in a family that already has 1 sibling with [autism spectrum disorder],” the researchers write.
Read more in this news article from the Simons Foundation Autism Research Initiative (SFARI).