New researchers suggest paternal obesity could raise the risk of having autistic children.
The finding requires more research in order to determine a causal relationship, but researchers believed paternal obesity could be an even larger autism risk factor than obesity in mothers, a Norweigan Institute of Public Health news release reported.
"We have a long way to go. We must study genetic factors in the relationship between obesity and autism, as well as environmental factors associated with switching the genes on or off - so-called epigenetic factors," Doctor Pål Surén said in the news release.
The researchers looked at data from the Norwegian Mother and Child Cohort Study (MoBa), which encompasses over 90,000 Norwegian children who were three, five, and seven years of age. The parents of the study subjects filled out questionnaires regarding their mental and physical health.
Out of the study participants 419 children (about 0.45 percent) had an autism spectrum diagnosis (ASD). Out of the sample 22 percent of mothers were overweight as well as 43 percent of the fathers. About 10 percent of mothers and fathers were considered to be obese.
The team found little correlation between maternal obesity and autism in the child; children with obese fathers were found to have twice as high of a risk of Asperger's compared to those with fathers of a normal weight.
"We were very surprised by these findings because we expected that maternal obesity would be the main risk factor for the development of ASD. It means that we have had too much focus on the mother and too little on the father. This probably reflects the fact that we have given greater focus to conditions in pregnancy, such as the growth environment for the [fetus] in the womb than both environmental and genetic factors before conception," Surén said.
Genetic mutations could account for this change. If a section of chromosome 16 is missing it can cause morbid obesity or developmental disorders in children.
Epigenetics could be another explanation for this phenomenon, which occur when environmental factors turn a gene on or off.
"We still know very little about how epigenetic changes in germ cells are affected by obesity or other environmental factors but animal experiments have shown that obese males have offspring with altered gene expression in early growth regulation," Surén said.
The researchers plan to conduct follow-up studies in hopes of learning more about the link between paternal obesity and the risk of developmental disorders in offspring.
"We have begun to sequence all genes to find mutations and we must do more epigenetic analysis. If there is a correlation between obesity and ASD, this is a risk factor where the incidence is increasing in the population. Further research is therefore of great importance to public health," Surén said.
