New Clues on Autism Susceptibility

New Clues to Who Is Susceptible to Autism Via Vaccine Injury

 By Scott Laster 


A study titled “Familial Risk Factors in Autism” by Brimacombe et al was published in 2007 in the Journal of Child Neurology.  The results of this study may have implications on the current debate over philosophical exemptions in New Jersey, and may yield important clues on how future public health policy might identify sub-groups that are susceptible to vaccine injury.

In this study, family histories were examined in a cohort of 164 autistic children referred to The Autism Center at New Jersey Medical School-University of Medicine and Dentistry of New Jersey in Newark over a 2-year period (2001-2003).  The study found that a family medical history of certain illnesses was prevalent at significantly higher rates in the autism cohort versus the general population, such as thyroid disorders (20.8% in autism cohort vs 1.6% in general population), rheumatoid arthritis (10.4% vs < 1%), epilepsy (5.6% vs < 1%), and diabetes (23.2% vs 6.3%).   The average age of the autism cohort studied during this 2001-2003 period was 6.6 years.

This study did not define autism prevalence rates in New Jersey for sub-populations with each specific family medical history.  However with the autism prevalence data from the CDC for the state of New Jersey for the 1994 birth cohort (MMWR Morbidity and Mortality Weekly Report Surveillance Summaries February 9, 2007), calculations can be performed on this data to approximate the “risk of autism” for children in New Jersey born with certain family medical histories.

Disclaimer: the following calculations are mine only, and have not been vetted with the authors of the “Familial Risk Factors in Autism” study.  As a further disclaimer, there is nothing in the “Familial Risk Factors in Autism” study which refers to vaccines or indicates in any manner that the authors think that vaccines might be a causal factor in autism (on the contrary, the authors write that “… This work supports the underlying presence of genetic factors in the etiology of autism.”)

Per the CDC autism prevalence data, the 1994 birth cohort in New Jersey had a 1 in 94 risk of developing autism.  In the following table, I calculated the risk of a child developing autism if born in that 1994 New Jersey cohort with certain family medical histories.  A child born to family with a history of thyroid disorders had a 1 in 7 risk of autism (over 13 times higher than the risk of autism in the general population).  For rheumatoid arthritis, the autism risk was at least 1 in 8 and potentially higher (as with some illnesses as noted in the table, the data on general population prevalence in the “Familial Risk Factors in Autism” was insufficient to determine if autism risk was higher than 1 in 8).  For epilepsy the risk was at least 1 in 15 (or higher); for diabetes, the autism risk was 1 in 26.

(Click on the graphic to enlarge it please.)

Notes on these calculations:  Although it is plausible that a child whose family medical history included multiple of these illnesses would have an autism risk higher than the autism risk from each individual illness, the “Familial Risk Factors in Autism” study did not evaluate such combinations.  Similarly although it is plausible that a boy with family medical history of thyroid disorders would have an autism risk even higher than the 1 in 7 shown in the table, the “Familial Risk Factors in Autism” study did not evaluate the risk of family medical history for boys versus girls.  Thus to be conservative, I’ve not included any analysis of autism risk for boys versus girls or for family medical history with multiple illnesses in this table.

What are the potential lessons from this analytical exercise?

1.    If vaccines contribute to autism in a susceptible sub-population, the public health challenge will be to determine how to identify the sub-groups that should utilize an alternative vaccination schedule or go without vaccines altogether (and thus rely upon the overall ‘herd immunity’ to protect them from vaccine-preventable diseases, as is already the policy for certain susceptible sub-populations).  The absence of an answer on how to identify the susceptible sub-groups could be a major factor in the reluctance of the CDC to formally concede that vaccines may be linked to autism in a susceptible group of children.  However, the “Familial Risk Factors in Autism” study provides clues as to the identity of the susceptible sub-groups, and further provides a method (clinical analysis of family medical history) to determine whether an individual child belongs to a susceptible sub-group. 

2.    The “Familial Risk Factors in Autism” did not study vaccines and does not provide any evidence (one way or the other) as to whether vaccines cause autism.  However, it does provide evidence that New Jersey families with certain family medical histories have a far higher risk of a child developing autism.  This research was recently published in 2007, and has not yet had time to be incorporated into public health policy such that susceptible New Jersey families could obtain a medical exemption based upon family medical history.  Many New Jersey families, after much personal research, have concluded that there is a significant possibility that vaccines contribute to autism.  Suppose that a New Jersey family with a family medical history of thyroid disorders knows that their child has a 1 in 7 chance of developing autism (based upon the above analysis of the “Familial Risk of Autism” study), and also has concluded that vaccines will further increase their child’s risk of autism.  Shouldn’t such a family be allowed to have a philosophical exemption from vaccines?


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