New Study Updates Sibling Recurrence Rates of Autism to 20.2% from 18.7%
Younger siblings who are male, have an affected female sibling or multiple affected siblings, or who are impacted by social inequities
should be very closely watched for early signs of autism
(New York, NY –July 16, 2024): A new study published today in the journal Pediatrics reports a 20.2% recurrence rate of Autism Spectrum Disorder (ASD) in children who have a younger sibling with autism. This is seven times higher than the current general population rate of 2.8%. This study replicates and extends findings published in 2011 and uses a larger, independent, and more diverse sample than the 2011 original study, which reported a recurrence rate of 18.7%. The difference is not statistically significant.
The current prospective longitudinal study obtained an updated estimate of sibling ASD recurrence using a multi-national database of infants with older autistic siblings. Data were collected from 18 sites in the Autism Baby Siblings Research Consortium, an international network studying the earliest manifestations of ASD. 1605 infants with an older autistic sibling were followed from early in life to 3 years, when they were classified as ASD or non-ASD.
Male infant sex and having more than one older affected sibling together predicted the highest rate of recurrence. Sex of the older sibling (aka the “proband”) also influenced recurrence rates, with siblings of female probands significantly more likely to develop ASD than siblings of male probands. Notably, contextual factors such as low socioeconomic status (measured by maternal education) were also associated with an increase in recurrence. This suggests that infant monitoring should be based on both genetic and contextual factors.
Variables Associated with Recurrence and the Recurrence Rates:
Infant sex
Male recurrence rate = 25%
Female recurrence rate = 13%
Number of autistic children in family
Recurrence rate if more than one autistic sibling = 37%
Recurrence rate if only one autistic sibling = 21%
Sex of proband (i.e. sex of older autistic sibling)
Recurrence rate if first autistic child female = 34.7%
Recurrence rate if first autistic child male = 22.5%
Race
Non-White recurrence rate = 25%
White recurrence rate = 18%
Maternal education
Recurrence rate if mother has high school or less education = 32%
Recurrence rate if mother has graduate degree = 17%
The Autism Science Foundation was one of several funders of this study. ASF Chief Science Officer Dr. Alycia Halladay serves as program officer for the Autism Baby Siblings Research Consortium. The collection and analysis of this larger dataset was made possible because of a shared BSRC database, funded by ASF.
“Given the increased risk to younger siblings, it is critical that subsequent children in families with a child diagnosed with ASD be closely monitored and referred promptly for diagnostic evaluation if early warning signs are present, said Halladay. “Younger siblings who are male, have an affected female sibling or multiple affected siblings, should be very closely watched during early development. More must be done to ensure that infants with a higher likelihood of diagnosis receive continuous monitoring, especially those from economically disadvantaged communities.”
The Autism Baby Siblings Research Consortium (BSRC) is a multidisciplinary, collaborative community of researchers and clinicians committed to understanding the developmental origins and earliest signs of autism spectrum disorder (ASD) by studying infants with risk of a diagnosis – including infant siblings, those with rare genetic disorders and premature infants. Over the last decade, through rigorous studies conducted by investigators across multiple sites, the BSRC has identified both behavioral and biological markers of risk and disrupted development prior to the age of diagnosis, sparking studies of early intervention in infancy. The BSRC shares this knowledge with investigators, parents, and clinicians who provide care to communities and families, and shares research strategies with all those investigating high risk populations. You can read about the work of the BSRC on www.babysiblingsresearchconsortium.org.
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About the Autism Science Foundation
The Autism Science Foundation (ASF) is a 501(c) (3) public charity. Its mission is to support autism research by providing funding to scientists and organizations conducting autism research. ASF also provides information about autism to the general public and serves to increase awareness of autism spectrum disorders and the needs of individuals and families affected by autism. To learn more about the Autism Science Foundation, or to make a donation, visit www.autismsciencefoundation.org.