One in 68 children are affected by autism spectrum disorder.
One in 68 children in the USA are affected by autism spectrum disorder (ASD). As the condition tends to run in families, most experts agree that autism is largely inherited.
Although previous studies have identified some genes that are associated with autism, one of the new studies - from researchers at Johns Hopkins Medicine in Baltimore, MD, and published in the International Journal of Epidemiology - has found distinct patterns of epigenetic tags that may play a role in regulating the activity of autism-linked genes.
The Johns Hopkins team collected DNA from the sperm of 44 fathers who already had a child with autism and who were expecting new babies with their partners. In the early stages of the new pregnancies, sperm was collected from the fathers enrolled in the study, and the children were assessed for symptoms of autism at 1 year of age.
The researchers searched for epigenetic tags at 450,000 different positions in the genome.
The likelihood of a tag occurring at a particular position in the genome was then referenced against the Autism Observation Scale for Infants (AOSI) scores of the children.
Overall, the researchers found 193 different sites where there was a statistically significant relation between the presence or absence of an epigenetic tag and AOSI scores.
Many of the genes near these implicated sites are involved in developmental processes, say the study authors - neural development, especially.
Four of the 10 sites most strongly linked to AOSI scores were also located near genes that previous studies have found to be associated with Prader-Willi syndrome - the genetic disorder that shares some symptoms with autism.
The study reports that several of the significant epigenetic patterns were also found in the brains of people with autism.
Next, the Johns Hopkins researchers will attempt to replicate their results among a larger sample group and will also assess the occupations and environmental exposures of the fathers.
How long does it take for ASD children to be diagnosed?
Looking at autism diagnosis among young children, researchers from Doernbecher Children's Hospital Oregon Health & Science University and Oregon State University in Corvallis assessed data from the 2011 Survey of Pathways to Diagnosis and Services.
The study included 1,420 children with ASD and 2,098 children with nonspecific intellectual disability/developmental delay (ID/DD).
The research team found that the parents of ASD children first became concerned about their child's development at around 2 years of age, and they first discussed these concerns with health care professionals at around 2.3 years.
In comparison, the parents of ID/DD children first had concerns at around 3 years, and they reported these concerns to health care providers around 3.2 years of age.
The study shows that children with ASD had 14% fewer proactive provider responses to parental concerns than children with ID/DD. This means that health care providers were less likely to conduct developmental tests or refer ASD children to a specialist. Providers were also more likely to tell the parents of ASD children that their child will "grow out of it."
The researchers also assessed differences in responses between providers who were more passive and reassuring with those who were more proactive, and found that the more passive providers waited as much as 2 years longer to diagnose ASD.
The study reports that overall, ASD children were not diagnosed until 5 years of age, on average - almost 3 years after parents first voiced concerns to health care professionals.
The researchers know that early identification of ASD is beneficial to children and their families. Unfortunately, many families experience long delays between when they first have concerns and when their child gets diagnosed with ASD.
This study implies that the behavior of health care providers is likely a very important factor in delayed autism identification.
References:
1. Parental concerns, provider response, and timeliness of autism spectrum disorder diagnosis, Katharine Zuckerman, et al., The Journal of Pediatrics, http://dx.doi.org/10.1016/j.jpeds.2015.03.007, published online 14 April 2015, abstract.
2. Paternal sperm DNA methylation associated with early signs of autism risk in an autism-enriched cohort, Andrew Feinberg, et al.,International Journal of Epidemiology, doi: 10.1093/ije/dyv028, published online 14 April 2015, abstract.
3. Johns Hopkins Medicine news release, accessed 15 April 2015 via EurekAlert.
4. Elsevier Health Sciences news release, accessed 15 April 2015 via EurekAlert.
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