Monday 7 July 2014

Reproductive stoppage related to autism

The paper by Thomas Hoffmann and colleagues [1] on reproductive stoppage - the decision to not have more children - in couples with a child already diagnosed with an autism spectrum disorder (ASD) is the source for today's post. This is both an important and delicate area to talk about so I tread very carefully in my discussions.
The Holy Infants @ Wikipedia 

A few details first:

  • Based on records held at the California Department of Developmental Services, children born between 1990 and 2003 with a subsequent diagnosis of ASD were identified, and details on full and half-siblings extracted.
  • Data from control participants without any record of autism or ASD were compared to ascertain "the reproductive behaviors of parents after the birth of a child with ASD vs an unaffected child".
  • Results: 19 710 "case families" were initially identified from Services records and compared against data from 36 215 "pure control families". Whilst for the first few years after the birth of a child who was subsequently diagnosed with an ASD case families showed reproductive behaviour "similar to that of control parents", as time went on reproductive stoppage became more pronounced. Families with a child with autism were about a third less likely to have subsequent children than control families. This effect was also noted when later-born children were diagnosed with an ASD and "among women who changed partners".

Although the precise reasons why reproductive stoppage occurred with greater frequency among families affected by ASD are not given in the Hoffmann paper, some of the associated media discussion of this study (see here) talk about possible influences. It "could be due to concerns about having another child with the disorder or that parents feel they are unable to care for additional children after having one on the spectrum already" are some of the ideas being suggested. Parental stress is another concept banded around by some too.

Having talked about recurrence risk and autism previously on this blog (see here), there is another important message to be taken from the Hoffmann study outside of reproductive behaviours in families with a child with ASD. The issue of stoppage can have an important effect on discussions about recurrence risk as per other reports on this topic [2] and as has been suggested in the latest paper, how recurrence risk estimates can be under-estimated as a result. Indeed, the authors reported that when taking stoppage into account, recurrence risk estimates move up a few percentage points for both full and half siblings (8% full siblings becomes 10% and 3% for half-siblings becomes ~5%) based on their data. I might add that birth order studies in connection to ASD may also be similarly influenced by stoppage too [3].

I was also taken by some discussion on a paradox as a function of the Hoffmann results. The idea being that if autism was wholly genetic, then such reproductive stoppage should be "diminishing" any classical genetic fragility to autism over time. Clearly however, this is not the case as rates of autism, estimated rates of autism, are still climbing and much greater focus is being directed to other factors in autism causation outside of the 'genes are king/queen' mantra. Interestingly, published in the same journal as the Hoffmann paper, another paper by Kristen Lyall and colleagues [4] perhaps provides some further discussion on this topic and their conclusions supporting a: "role of additive genetic influences in concentrating inherited ASD susceptibility in successive generations and the potential role of preferential mating, and suggest that typical variation in parental social functioning can produce clinically significant differences in offspring social traits". I might add that I'm not necessarily coming down on the side of assortative mating being the ultimate factor affecting offspring autism risk, but it might offer at least some explanation for the autism genetics paradox also tied into concepts like the broader autism phenotype (BAP) too.

As mentioned at the beginning of this post, the issue of reproductive stoppage when it comes to families touched by autism is both an important and sensitive issue. The decision or not to have additional children when a family is already affected by autism is a personal one and most likely influenced by many different and often very individual factors. I don't doubt that some of those factors are the same that every family faces irrespective of autism or not: time, space, money, etc. but perhaps with the added discussions about 'risk' and the various 'what if' scenarios...

Music to close, and another song doin' the rounds in our house: Let it go (from Disney's Frozen movie). A treat also for some of my brood for bringing home their first Martial Arts trophies... Kiai!


[1] Hoffmann TJ. et al. Evidence of Reproductive Stoppage in Families With Autism Spectrum Disorder. JAMA Psychiatry. 2014. June 18.

[2] Jones MB. & Szatmari P. Stoppage rules and genetic studies of autism. J Autism Dev Disord. 1988 Mar;18(1):31-40.

[3] Schmidt K. et al. Brief report: Asperger's syndrome and sibling birth order. J Autism Dev Disord. 2013 Apr;43(4):973-7.

[4] Lyall K. et al. Parental Social Responsiveness and Risk of Autism Spectrum Disorder in Offspring. JAMA Psychiatry. 2014. June 18.

---------- Hoffmann, T., Windham, G., Anderson, M., Croen, L., Grether, J., & Risch, N. (2014). Evidence of Reproductive Stoppage in Families With Autism Spectrum Disorder JAMA Psychiatry DOI: 10.1001/jamapsychiatry.2014.420

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