There has been an unprecedented increase in recent years in the number of children diagnosed with autism spectrum disorders (ASD).  A variety of elements are suspected of playing a role (see our recent post linking environmental toxins to autism). 

Researchers have known that a higher incidence of autism exists among twins¹, and this new study confirms a substantially higher risk of autism in identical twins as compared to fraternal twins.²  The report, published in the Archives of Pediatrics and Adolescent Medicine, studied 277 twin pairs in which at least one had an autistic disorder.

Researchers found that when one identical twin developed an autistic disorder, the other twin did 88 percent of the time. That compared with 31 percent among fraternal twins. Fraternal twins share only 50 percent of their genes and are no more genetically similar than non-twin siblings, unlike identical twins, who share 100 percent of their genes. 

Researchers also found that identical twins had greater similarities in the form of autism, level of functioning and risk of intellectual impairment.

One of the authors of this study, Dr. Paul Law, of the Kennedy Krieger Institute in Baltimore said, “Autism research has been guided by one important observation for the past several decades - that autism has a large genetic component. That observation was made through twin studies.”

Autism spectrum disorders (ASD) impair the ability to communicate, socialize and relate to others. These disorders are typically diagnosed in early childhood and range from the more severe form of autism to a much milder form, Asperger’s syndrome. A person with Asperger’s Syndrome has normal intelligence but much difficulty with social skills missing important non-verbal cues such as body language and vocal tone.

The number of children diagnosed with ASD has risen substantially in recent years, causing many people to wonder about the causes and possible links to a variety of elements.  These new findings confirm the role of genetics in the development of autism spectrum disorders.

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Marie Oser is a best-selling author, writer/producer and host of VegTV, Follow Marie on Twitter: http://twitter.com/vegtv

Sources:

1. Increased Rate of Twins among Affected Sibling Pairs with Autism
   Catalina Betancur, ¹ Marion Leboyer, and Christopher Gillberg.
   Am J Human Genetics. 2002 May; 70(5): 1381–1383.
2. Rebecca E. Rosenberg; J. Kiely Law; Gayane Yenokyan; John McGready; Walter E. Kaufmann; Paul A. Law. Characteristics and Concordance of Autism Spectrum Disorders Among 277 Twin Pairs. Arch Pediatric Adolescent Medicine, Oct 2009; 163: 907 - 914.