Feb 29 2008

Has the Government Conceded Vaccines Cause Autism?

No. But David Kirby and other anti-vaccinationist ideologues and members of the so-called mercury militia would like you to think so. For background, the Autism Omnibus refers to a set of hearings before the Vaccine Injury Compensation Program regarding claims by about 5000 parents that their childrens’ autism was caused by vaccines. These claims are primarily based upon the various hypotheses that the MMR vaccine, or thimerosal in some vaccines (but not MMR), or the combination of both, is a cause of autism.

So far there have been hearings, but only one final decision. In November the US government settled one case in favor of the petitioner. This is the case those who have supported the failed hypothesis that vaccines cause autism now point to as admission that they were right all along (or at least as a means of stoking the flames of fear about vaccines.) But the US government did not admit vaccines cause autism – they conceded one case that is highly complex and not necessarily representative of any other case and cannot be reasonably used to support the vaccine/autism connection.

David Kirby, author of Evidence of Harm, wrote a highly misleading article the other day in the Huffington Post on this issue. Orac has already done an excellent job of tearing down Kirby’s claims. He points out that legal cases are often decided for legal – not necessarily scientific – reasons. That the government only conceded that “compensation is appropriate.” That is all – they conceded nothing about the larger question of vaccines and autism. Orac also points out that if this case were a concession of a connection why would the petitioner’s lawyers settle and give away a case that could win them all their other cases?

David Kirby has also written a follow up article, where he publishes verbatim the US government’s decision. Kirby asks his readers:

If you feel this document suggests that some kind of link may be possible, you might consider forwarding it to your elected representatives for further investigation.

But, of course, if you feel that this document in no way implicates vaccines, then let’s just keep going about our business as usual and not pay any attention to all those sick kids behind the curtain.

I think Kirby is hoping that most people will not have the patience or medical background to read and understand the entire document, and that they will come away with a vague notion that there must be something to all this vaccine fear-mongering. What does the document really tell us?

To summarize the case history, the child in the case appeared normal and healthy, except for chronic otitis media, until about 20 months of age at which time he had a series of vaccines according to the routine vaccination schedule. Two days later the child had a fever to 102.3, was lethargic, irritable, and would arch his back when he cried. The child then developed a rash. It was later determined that the child had: “encephalopathy progressed to persistent loss of previously acquired language, eye contact, and relatedness.” The child regressed and developed symptoms similar to those of autism spectrum disorder. However, the child does not have autism – he has a regressive neurological disorder that includes blood and muscle abnormalities not seen in autism, and any clinical resemblance to autism is not a reflection of a common cause.

Six years after symptoms began the child also developed partial temporal lobe epilepsy that required treatment.

During this time the child also had an extensive workup, which discovered:

A CSF organic acids test, on January 8, 2002, displayed an increased lactate to pyruvate ratio of 28,1 which can be seen in disorders of mitochondrial oxidative phosphorylation.

A muscle biopsy test for oxidative phosphorylation disease revealed abnormal results for Type One and Three.

In February 2004, a mitochondrial DNA (“mtDNA”) point mutation analysis revealed a single nucleotide change in the 16S ribosomal RNA gene (T2387C)

It if often difficult or impossible to draw firm conclusions from a single case, so I will lay out what I see as all the possible alternative hypotheses to explain this information.

1) One possibility is that the child was perfectly normal prior to the vaccines, which caused an encephalitis (inflammation of the brain) which caused brain damage, including the later seizures. The metabolic disorder and mutation may be a red herring and have no bearing on the child’s clinical condition.

2) The mitochondrial disorder predisposed the child to have a reaction from the vaccines, resulting in encephalitis. The subsequent neurological regression was due to some combination of the vaccine-induced encephalitis and the underlying mitochondrial disorder.

3) The child’s mitochondrial mutation is the primary cause of their neurological regression, but that this regression was exacerbated by the vaccine-induced encephalitis (this seems to be the US government’s conclusion).

4) The child has a mitochondrial encephalopathy which is the sole cause of all of the child’s neurological signs and symptoms. The reaction to the vaccines may have played no role at all in the subsequent regression, and the child’s current neurological condition is exactly what it would have been had they never been vaccinated. It is even possible that the encephalitis was merely the first manifestation of the mitochondrial disorder and the timing after the vaccines was merely coincidental.

That lays out the spectrum of possibilities in this case. At this point in time we do not have (or at least I am not privy to) sufficient scientific information to say definitively where along this spectrum the truth lies. The US government’s decision was based partly on this uncertainty – erring on the side of compensating the child and family.

But we can discuss the plausibility of each scenario. Kirby dismisses anything resembling option 4, but his dismissal is naive and unjustified. In fact the patient’s clinical syndrome resembles what is called a mitochondrial encephalopathy – with increased lactic acid, abnormal muscle biopsy, neurological regression, appropriate age of onset, even seizures. It is probably not a coincidence that the child has a point mutation in a gene that has been previously linked to these very mitochondrial disorders. Kirby incorrectly argues:

While it’s true that some inherited forms of Mt disease can manifest as developmental delays, (and even ASD in the form of Rhett Syndrome) these forms are linked to identified genetic mutations, of which T2387C is not involved. In fact little, if anything, is known about the function of this particular gene.

This is misleading. Kirby refers to “this particular gene” which makes me think that he believes T2387C is a gene. It’s not – it describes a point mutation (at location 2387 a thymidine has replaced a cytosine). The gene is the 16S ribosomal RNA gene. Mutations in this gene have been identified to cause mitochondrial encephalopathy. So Kirby is just wrong. It is true that I could not find that this specific mutation has been identified before, but that is common in genetics – a disease is linked to point mutations in a specific gene (or perhaps specific regions of a gene) but most or all families identified have their own specific mutation.

This makes option 4 very plausible – it would be an incredible coincidence if this child just happened to have a mutation in a gene that was known to cause their exact constellation of neurological signs and symptoms and yet the mutation was not the sole or primary cause of those symptoms.

But it does not rule out option 3 – that the mitochondrial disorder was the primary cause of the child’s neurological disorder but that a reaction to the vaccines worsened the ultimate symptoms. Therefore the government’s decision was reasonable – but is absolutely not a concession about any claim made by the petitioners concerning a link between vaccines an autism.

It does, however, make any hypothesis resembling option 1 or 2 extremely unlikely. Further testing regarding the physiological effects of this child’s specific mutation would be helpful, and such testing may be under way but I could find nothing published to date. It is theoretically possible that the identified mutation does not cause a change in the gene product or mitochondrial function, and is therefore just a coincidence. But this is unlikely given the clinical features in this case are a good match to known mutations of that gene.

Kirby, however, apparently wants to wring as much fear and confusion out of these events as he possibly can. So now he speculates wildly that maybe children diagnosed with autism really have this mitochondrial disorder combined with vaccines (he has to keep vaccines in the loop). Given the rarity of such mutations, and the fact that there were specific features in this case that would likely be uncovered in the routine evaluation of a child with autism (like an elevated lactic acid), it is highly unlikely that there are many children with vaccine-triggered mitochondrial encephalopathy mimicking autism out there.

It has been found that some children with autism have mitochondrial dysfunction – one study found that 7.2% of subjects with autism had “definite mitochondrial respiratory chain disorder.” Poling et al, in response to this child’s case, did a retrospective study of children with autism and with other neurological disorders and found that “Aspartate aminotransferase was elevated in 38% of patients with autism compared with 15% of controls.” Such findings are preliminary – the only conclusions that can be drawn is that the association between autism and metabolic disorders requires further investigation. However, these studies did not look at the incidence of suspicious mitochondial mutations in autism, and these findings may not be relevant to this case.

Kirby also wildly speculates that perhaps the evil toxins in vaccines caused the mutation in the first place. He writes:

Use of the AIDS drug AZT, for example, can cause Mt disorders by deleting large segments of mitochondrial DNA. If that is the case, might other exposures to drugs or toxins (i.e., thimerosal, mercury in fish, air pollution, pesticides, live viruses) also cause sporadic Mt disease in certain subsets of children, through similar genotoxic mechanisms?

Among stiff competition, this is perhaps the most absurd and scientifically ignorant thing Kirby has every written. AZT does NOT cause a genetic disorder. AZT blocks DNA replication (it blocks the copying of DNA) – that is its mechanism as an anti-retroviral drug. In patients it can also block mitochondrial DNA replication, thereby causing mitochondrial depletion. This results in there being too few mitochondria (the energy factories of cells) in some cell populations and causes dysfunction in tissue that is especially susceptible to the effects of this dearth of mitochondria. This is a side effect of AZT and also other retrovirals because of sustained use at doses designed to inhibit DNA replication. This does result in some effects that are similar to mitochondrial genetic disorders – because both result in insufficient mitochondrial activity. But that is the only similarity. AZT does not cause a disseminated somatic mutation, which is the incredible analogy that Kirby is making.

What Kirby is suggesting is that in infants and toddlers toxins can cause the same point mutation in millions of different cells throughout the body. Toxin-induced mutations do not cause genetic diseases, unless they occur in a germ cell in which case a mother or father can pass the mutation onto their children. If it occurs in the womb then large cell populations may be affected (whatever cells derive from the cell that had the mutation). But in a child a point mutation would affect only one cell and any cells that derive from it. A toxic mutagen would cause different random point mutations in different cells. This could not cause the mitrochondrial encephalopathy in this child. It can increase the risk of cancer, because cancer can develop from a single mutation in a single cell that causes it to become neoplastic.

Conclusion

This is a unique and idiosyncratic case that raises more questions than it answers. In my opinion as a neurologist, with the information provided, the child has a mitochondrial encephalopathy. The role of the vaccines is unclear, but at worst a rare vaccine reaction exacerbated the underlying mitochondrial disorder. This case has no clear implication for the larger question concerning vaccines and autism, which is likely why both sides agreed to settle.

Yet those who insist, despite the evidence, on claiming that vaccines or mercury are linked to autism are likely to add this permanently to their litany of misinformation and fear-mongering.

Note: I am searching for any follow up information pertinent to this case and will post any addendum here.

Like this post? Share it!

66 responses so far