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Autism Runs In Families

Higher Risk For Younger Siblings Of Children With Autism

We’ve known for some time that Autism Spectrum Disorders (ASDs) are more likely to recur in families where there is already at least one child with an ASD. A 2011 study published in the journal Pediatrics suggested that the recurrence rate is higher than previous believed. The best estimates were that a couple’s risk of having another child with an ASD was between 3% and 14%, but this study estimates the risk overall at approximately 18.7%.

This may not sound like a large difference from what we already knew, but the strength of this research is in its design. This is the first study to follow infants born into families with at least one child with an ASD and evaluate them at a minimum of 3 years old, an age when most ASDs can be diagnosed with 85% certainty. This study also enlisted the help of experts to confirm the diagnoses of all the children involved, as opposed to relying on parents to report the ASD status of their children.


The study also showed that two risk factors predicted an additional risk of having another child with an ASD. The first was the sex of the next child – boys were almost 3 times as likely as girls to be born with an ASD if they had an older sibling with an ASD. The second was the number of children with an ASD that a couple already has – a family with multiple children with ASDs are more than twice as likely to have another child with an ASD, versus a family that already has only has one child with an ASD.


Unfortunately there is no test or method available to tell a couple their individual risk of having a child with an ASD. The risk percentages described in the study are based on population statistics and can give you a general idea of the risk. It’s important for couples that already have a child or children with ASDs to have this information because it can help them to make decisions about having another child and it can put them on alert to monitor the developmental milestones of subsequent children. The advantage of identifying ASDs as early as possible is that disabilities these children experience can be minimized with early interventions like special education and therapy.

ASDs are characterized by problems in 3 key areas:

1) social interaction
2) language
3) behavior

Some warning signs include:

1. Social skills

- Fails to respond to his or her name
- Has poor eye contact
- Appears not to hear you at times
- Resists cuddling and holding
- Appears unaware of others’ feelings
- Seems to prefer playing alone — retreats into his or her “own world”

2. Language

- Starts talking later than age 2, and has other developmental delays by 30 months
- Loses previously acquired ability to say words or sentences
- Doesn’t make eye contact when making requests
- Speaks with an abnormal tone or rhythm — may use a singsong voice or robot-like speech
- Can’t start a conversation or keep one going
- May repeat words or phrases verbatim, but doesn’t understand how to use them

3. Behavior

- Performs repetitive movements, such as rocking, spinning or hand-flapping
- Develops specific routines or rituals
- Becomes disturbed at the slightest change in routines or rituals
- Moves constantly
- May be fascinated by parts of an object, such as the spinning wheels of a toy car
- May be unusually sensitive to light, sound and touch and yet oblivious to pain

[Courtesy: The Mayo Clinic]

For a detailed look at ASDs and what can be done about them, see:


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