Increased Risk for Autism – Having on older sibling with the Disorder.

Autism and family Most everyone has had a moment with a child with Autism. Whether it is with a family member, a friend, or a stranger. Let’s be honest, not all of these encounters have been positive. Children with Autism have a hard life in front of them. So does the parent, sibling, teacher , and countless others that are involved in the child’s well being.

Anger, frustration, despair, restless nights, expanding expenses and many more descriptions can be said about those close to Autism.

Countless studies, pharmaceutical research, scientific research has been done over the years to better understand this medical condition.

Recently, it was evaluated to see if there was a genetic component to this condition. A new study in Denmark looked at this and found that children who have an older sibling, one who had autism, were seven times more likely than other kids to be diagnosed with the disorder themselves.

Previous theories had given almost a fifty percent chance. Seven times more likely is smaller, but it is also more focused. It also looked at half siblings. If they shared the same mother, there was also a higher than average risk.

This certainly doesn’t explain everything, autism is very complex and misleading. If it were just genetics alone, it should be higher than seven times.

According to the CCD – in the United States, about 1 in every 88 children will develop Autism.

Denmark Study

Therese Gronborg, one of the lead researchers into Autism, at Aarhus University and her colleagues reviewed the numbers for over 1.5 million children born in Denmark from 1980 to 2004. They used birth, civil and psychiatric registries to track them.

Through 2010, just over 13,000 of them had been diagnosed with an ASD. That included 276 children with an older sibling with autism who were also diagnosed with the disorder.

The researchers found the likelihood of a younger sibling being diagnosed with autism when an older sibling had an ASD varied between 4.5 and 10.5 percent, with an average of about 7 percent. There was no clear increasing or decreasing trend during the study period.

The researchers also looked at the possibility that children in families with Autism, are more likely to be diagnosed because they have already seen many symptoms in their other children. This is an increase in awareness.

Half Siblings

The extra risk of autism was smaller. Younger half-siblings who shared a father with an older sibling had a 1.5-times greater risk of ASDs. This could be more of chance than anything. Further studies will evaluate this.

Children who shared a mother with a half-sibling had a 2.4-times greater risk if their older brother or sister had autism.

autism_siblings_1221Other Possible Causes

Therese Gronborg theorized that a woman’s lifestyle during pregnancy or something about the intrauterine environment could also be affecting her children’s risk of autism.

But it also could be in the upbringing, foods, and other unknown possibilities.

Denmark study different than other studies

Some studies have looked at twins while others have looked at Siblings.

Studies looking at Identical twins have found a wide variety of information. Recent research has shown a possible 38% – 97% chance of both children getting Autism. Some of the importance of this study showed a lower number for Dizygotic twins (Fraternal) and a higher number for Monozygotic Twins (Identical).

Research findings in 1977, 1979, 1985 and 1989 have all shown some variance of this finding.

Other studies have shown a 0-38% chance of have a second sibling getting Autism after the first one did (usually a younger sibling).

Other sibling studies show about a 12%-20% similarity.

A study in 2007 showed 86 families with 2 or more autistic children. 42 of the third born male children showed Autistic symptoms. This research gave about a 50% chance of passing on a gene mutation to their offspring.


The research time after time shows some genetic component. Whether those studies were done with twins or siblings. The recent research in Denmark seems to be a large study – look at over 1.5 million children over many years. This study is important to help correlate a relation between Autism and family members.

It is certain that we don’t yet have enough information. But we are gaining more and more as time progresses.

Learn more about Autism below:

1.)  Autism

2.)  Asperger Syndrome

3.)  Is There a Relationship Between Vaccinations and Certain Diseases Such as Autism

4.)  Link to Autism? Vaccine Court Says “No”!

5.)  Trouble Brewing For Doctor Who Linked Autism and Vaccines

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