Understanding autism leapt forward this year with University of Bristol’s 14,500 person study in Scientific Reports, showing a 53 percent increased risk of autism if the child’s maternal grandmother smoked during pregnancy. Similarly, granddaughters experienced a 67 percent increased risk of displaying traits associated with autism, like sensory sensitivities or poor social communication.

Previous studies have pointed toward a genetic link and autism. In 2013 Danish researchers showed autism risk of 7 percent in all siblings if one sibling had autism — seven times higher than observed in children without an autistic sibling. The risk was higher in half-siblings with the same mother rather than the same father, further suggesting the strong maternal link.

There are intriguing hypotheses for this gender disparity, the most obvious being mitochondria — our cell component driving metabolism through energy production like little batteries. Mitochondria are 100 percent inherited from our mothers. Our maternal grandmother gave our mother and us all our mitochondria. Mitochondrial have their own DNA — none of it comes from the male parent.

Another possibility is epigenome damage in our nucleus DNA — permanently turning off parts of some chromosome genes — like a permanent “detour” sign for a road that exists but is never used. Factors such as smoking, improper diet and infectious diseases expose a person to pressures that prompt chemical responses in DNA support structures. These responses cause changes in the epigenome, some can be damaging. Damage occurring in egg or sperm can be inherited. The skip-generation observation with autism remains incompletely explained.

What’s the take-home point? The damage done to your body isn’t done to only you. It is done to your children and your grandchildren. Quitting tobacco is a gift that lasts generations. A talk with your doctor today can prevent a harder talk with your future grandchildren.

Allan P. Frank, MD, MS

Alpena

Assistant Clinical Professor

MSU College of Human Medicine