From the Guidelines
The odds of having a second autistic child are significantly higher for parents who already have one child with autism, with a recurrence risk of approximately 18.7% for full siblings, as reported in a recent prospective longitudinal study 1.
Key Factors Influencing Recurrence Risk
- Genetic makeup: The strong genetic component of autism contributes to the increased risk, with heritability estimated to be around 90% 1.
- Identified genetic causes: If the first child has identified genetic causes for their autism, this may impact the risk for subsequent siblings.
- Family history: Multiple family members with autism can increase the risk for subsequent siblings.
Recurrence Risk Estimates
- For full siblings: approximately 18.7% 1.
- For identical twins: much higher, around 60-90% concordance rate.
Importance of Genetic Counseling
Parents considering family planning after having a child with autism may benefit from genetic counseling to better understand their specific risk factors and make informed decisions.
Environmental Factors
While the strong genetic component of autism is a significant factor, environmental factors may also play a role in how these genetic predispositions are expressed.
From the Research
Recurrence Risk of Autism Spectrum Disorder
- The recurrence risk of Autism Spectrum Disorder (ASD) in families with one affected child ranges from 3% to 18.7% 2.
- A study found that the odds of having another child with ASD increased by 16.2 folds if at least one parent had ASD, and by 7.4 folds if the affected child had intellectual disability 3.
- The risk of ASD recurrence is higher in siblings, with an 8.4-fold increase in risk compared to unaffected families, and a 17.4-fold increase in risk for childhood autism 4.
- The recurrence risk also varies by sex, with a significant difference in sibling ASD recurrence risk observed 4.
Factors Influencing Recurrence Risk
- Perceived genetic causes of ASD and family history of ASD are significant predictors of recurrence risk perceptions among parents of children with ASD 2.
- The broad-sense heritability of ASD without intellectual disability is estimated to be 64.6%, suggesting a greater genetic basis for this subtype of ASD 3.
- The risk of ASD recurrence is also influenced by the degree of relatedness, with a 2-fold increase in risk observed for cousin recurrence 4.