Education.com

Understanding Autism (page 2)

By Melinda Smith, M.A|Jeanne Segal, Ph.D.
Helpguide
Updated on Feb 18, 2011

One Baby's Story

Melanie is a healthy one-year-old, but her parents are worried because she’s not doing many things that her older brother did at her age. When he was one, Melanie’s brother loved to play peek-a-boo and mimic his mom’s expressions and gestures. Melanie, on the other hand, rarely makes eye contact or responds when her parents call her name. Furthermore, she doesn’t babble or make other baby noises. Her mom and dad try to engage her with toys, songs, and games, but nothing they do gets her interest, let alone a laugh or a smile.

Melanie’s parents have been waiting for her to catch up, but the gap between her and others her age is only getting wider. Last week, Melanie and her mom went to the zoo with some families from the neighborhood. The other babies pointed excitedly at the animals and stared in wide-eyed wonder, but Melanie didn’t pay any attention to either the exotic animals or the other group members. At the end of the day, one of the kids banged his knee and started crying. The other babies looked distressed and many started crying themselves. Melanie didn’t even seem to notice what was going on.

The Autism Spectrum Disorders

Autism is one of a group of developmental disorders known as the autism spectrum disorders (ASDs). All of the ASDs begin in childhood and involve delays in communication and social skills. They are known as spectrum disorders because every child on the autism spectrum is affected differently, with unique challenges, symptoms, and abilities.

Learn More

Causes of autism

The causes of autism are unknown, but most experts agree that both genetic and environmental factors are involved. One popular theory is that certain individuals are born with a genetic predisposition for autism that is then triggered by something in the environment, either while the baby is still in the womb or shortly after birth.

Genetic causes of autism

Research indicates that genes—particularly inherited genetic glitches and spontaneous DNA mutations—play a primary role in the development of autism. But no single gene is to blame. Scientists believe that at least 5 to 20 major genes are involved in autism, with many others also contributing to the risk.

The bulk of the evidence for autism’s hereditary component comes from twin studies. Multiple twin studies show that when one identical twin develops autism, the other twin will also develop the disorder approximately 9 times out of 10. In fraternal twins—who are no more genetically similar than normal siblings—the concordance rate is just 1 in 10.

Large epidemiologic studies also show that older parents are at a significantly higher risk of having autistic children. The age of the father appears to be particularly important. A recent Israeli study found that children born to fathers who were 40 or older were almost six times more likely to develop autism than the children of men younger than 30. This heightened risk is likely due to genetic mutations in sperm, which are more and more common as men age.

But while some specific chromosomal abnormalities and mutations appear to cause autism themselves, in the majority of cases, the interaction of multiple genes leads to a susceptibility to autism without directly causing it.

View Full Article

Add your own comment

Ask a Question

Have questions about this article or topic? Ask
Ask
150 Characters allowed

Washington Virtual Academies

Tuition-free online school for Washington students.