Alleged Cases of Vaccine Encephalopathy Rediagnosed Years Later as Dravet Syndrome

19 Aug

A case study released this week looks at 5 children who were considered to have vaccine encephalopathy caused by pertussis vaccinations. In this case study, all five children were found to have Dravet Syndrome, a genetic condition involving how the brain uses sodium.

The phrasing of “alleged cases” will likely draw some critique. Parents are very sensitive to the accusation that they didn’t see what happened, in this case seizures and regression following vaccination. Alleged in this case doesn’t challenge what the parents saw, but what it means. It appears that individuals with Dravert syndrome don’t get through childhood without regression (there don’t appear to be cases with the mutation and no syndrome in adults). In the words of the vaccine court, these individuals would have Dravert’s syndrome in any event, making it impossible to show that vaccines are the causation in fact.

Dr. Vincent Ianelli reports over at pediatrics.about.com that the cases include:

14-year-old mentally retarded boy with autistic features, who was a healthy infant until he got his vaccines when he was 7 months old
20-year-old with delayed development and autistic-like features who began having seizures right after getting vaccines at 2 months
2-year-old with a mild expressive speech delay who developed seizures after getting vaccines at age 4 months
4-year-old with “slowing development” who began having seizures after the six month vaccines
3-year-old regressed development and autistic-like features who began having seizures after getting vaccines at age 4 months

In these five case, genetic testing resulted in a diagnosis of Dravet Syndrome.

From Dr. Ianelli:

Dravet syndrome is a rare, genetic cause of encephalopathy that causes seizures that are hard to control and developmental delays.

Since fever is the usual trigger of the first seizure and subsequent seizures, it is important that children with Dravet syndrome get all of their vaccines, since natural infections will cause more fever and put them at risk for more seizures. In another study, “A retrospective study of the relation between vaccination and occurrence of seizures in Dravet syndrome,” only 16% of patients with Dravet syndrome had a vaccine related seizure as their first manifestation.

The researchers also state “that although vaccination might trigger an earlier onset of the presenting symptoms of Dravet syndrome, there is no evidence that the outcomes, in terms of subsequent seizure types or intellect, are any different between those patients with Dravet syndrome whose symptoms started within 2 days of vaccination and those whose symptom onset was not related temporally to vaccination.”

Here is the abstract:

Dravet syndrome is a rare epileptic encephalopathy linked to mutations in SCN1A (neuronal sodium channel ?1 subunit) and characterized by an onset in infancy with polymorphous seizure types and developmental decline. It was reported recently that a proportion of patients previously diagnosed with alleged vaccine encephalopathy might possess SCN1A mutations and clinical histories that enabled a diagnosis of Dravet syndrome, but these results have not been replicated. We present here the cases of 5 children who presented for epilepsy care with presumed parental diagnoses of alleged vaccine encephalopathy caused by pertussis vaccinations in infancy. Their conditions were all rediagnosed years later, with the support of genetic testing, as Dravet syndrome. We hope that these cases will raise awareness of Dravet syndrome among health care providers who care for children and adolescents and aid in earlier recognition and diagnosis.

This isn’t the first work linking alleged vaccine encephalopathy with Dravet syndrome in some cases. Last year a study in The Lancet, Effects of vaccination on onset and outcome of Dravet syndrome: a retrospective study (also summarized in Pertussis Vaccination Triggers Dravet Syndrome in Predisposed Children) came to the conclusion:

Vaccination might trigger earlier onset of Dravet syndrome in children who, because of an SCN1A mutation, are destined to develop the disease. However, vaccination should not be withheld from children with SCN1A mutations because we found no evidence that vaccinations before or after disease onset affect outcome.

The anchor author on that study has a previous study, De-novo mutations of the sodium channel gene SCN1A in alleged vaccine encephalopathy: a retrospective study. They found 11 of 14 patients with alleged vaccine encephalopathy had Dravet syndrome (SMEI). Here is the abstract:

BACKGROUND:
Vaccination, particularly for pertussis, has been implicated as a direct cause of an encephalopathy with refractory seizures and intellectual impairment. We postulated that cases of so-called vaccine encephalopathy could have mutations in the neuronal sodium channel alpha1 subunit gene (SCN1A) because of a clinical resemblance to severe myoclonic epilepsy of infancy (SMEI) for which such mutations have been identified.

METHODS:
We retrospectively studied 14 patients with alleged vaccine encephalopathy in whom the first seizure occurred within 72 h of vaccination. We reviewed the relation to vaccination from source records and assessed the specific epilepsy phenotype. Mutations in SCN1A were identified by PCR amplification and denaturing high performance liquid chromatography analysis, with subsequent sequencing. Parental DNA was examined to ascertain the origin of the mutation.

FINDINGS:
SCN1A mutations were identified in 11 of 14 patients with alleged vaccine encephalopathy; a diagnosis of a specific epilepsy syndrome was made in all 14 cases. Five mutations predicted truncation of the protein and six were missense in conserved regions of the molecule. In all nine cases where parental DNA was available the mutations arose de novo. Clinical-molecular correlation showed mutations in eight of eight cases with phenotypes of SMEI, in three of four cases with borderline SMEI, but not in two cases with Lennox-Gastaut syndrome.

INTERPRETATION:
Cases of alleged vaccine encephalopathy could in fact be a genetically determined epileptic encephalopathy that arose de novo. These findings have important clinical implications for diagnosis and management of encephalopathy and, if confirmed in other cohorts, major societal implications for the general acceptance of vaccination.

A recent study out of Germany took a bit more cautious interpretation: A retrospective study of the relation between vaccination and occurrence of seizures in Dravet syndrome. But the abstract does not address the question of whether outcome depends upon whether the first seizure is possibly vaccine related or not.

At least two cases of have been heard in the vaccine court claiming vaccine injury in children with Dravet syndrome. Both cases (here and here) were denied compensation.

More information about Dravet syndrome can be found at the NIH website, and dravet.org

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4 Responses to “Alleged Cases of Vaccine Encephalopathy Rediagnosed Years Later as Dravet Syndrome”

  1. brian August 24, 2011 at 19:01 #

    There’s a bit more to this story that is important in the effort to understand the recent and oft-repeated claim that the fact that the National Vaccine Injury Compensation Program compensated 83 families of children who developed seizure disorders along with alleged autistic traits supports the idea that vaccines (DPT or MMR) are responsible for many cases of autism. [Pace Envtl. L. Rev., No. 2, Winter, 2011]

    It’s important to understand that (1) vaccination with DPT or MMR frequently causes fever, and (2) genetically-determined epilepsy syndromes that include the development of autistic traits may initially manifest with febrile seizure.

    A recent, large retrospective study of the association of childhood vaccination with the onset of seizures affirmed that in half the cases of severe epilepsy syndromes that manifest in early childhood following months of apparently normal development the initial seizure is associated with vaccination. [Epilepsia, 52(8):1506–1512, 2011] A recent study of 70 cases of Dravet syndrome showed that in one-fourth (19/70) of cases seizures began following vaccination. [Epilepsia. 2011;52(1):175] Accordingly, it’s important to understand the difference between a vaccine revealing underlying pathology and a vaccine causing that pathology.

    Sixteen of nineteen children who had allegedly suffered vaccine-induced encephalopathy have now been demonstrated (in two different studies) to instead have Dravet syndrome, one of several epilepsy syndromes that develop early in life following months of apparently normal development. (The three other children examined in these studies had other defined epilepsy syndromes.) Dr Charlotte Dravet stated that the natural history of the syndrome named for her specifically includes the development of “autistic traits.” [Epilepsia.2006;47 Suppl 2:45-8] Indeed, autism—rather than mere “autistic traits”—is frequently comorbid with Dravet syndrome and with some other childhood epilepsies. [Epilepsia.2011 Apr;52 Suppl 2:44-9; Epilepsy Behav. 2011 Jul;21(3):291-5]

    Dravet syndrome (DS, or severe myoclonic epilepsy of infancy (SMEI)) is one of a group of related forms of epilepsy caused by mutations in a gene required for the proper function of neurons: like DS, migrating partial seizures of infancy, borderline severe myoclonic epilepsy of infancy, and generalized epilepsy with febrile seizures plus have also been attributed to defects in SCN1A, which encodes a subunit of a sodium channel; cases of other childhood epilepsy syndromes such as West syndrome (West syndrome—which includes infantile spasm with developmental delay as well as autistic features or autism—accounts for one-fourth of epilepsy cases that begin before twelve months of age) have also been associated with SCN1A mutations, although a minority of cases have been linked to mutations in other identified genes. These genetic syndromes cause profound changes in children who had for months apparently developed normally.

    The different expressions of these syndromes and the age of onset of symptoms is apparently related to the type of mutations present in each particular case (e.g., of the more than 650 different SCN1A mutations thus far reported in cases of Dravet syndrome, SCN1A mutations that truncate the protein product tend to produce more severe and earlier effects than do missense mutations of that gene, thus demonstrating that a single fully-functional copy of SCN1A is insufficient for normal development; similarly, de novo mutations that occur after the initial cell division following fertilization may produce somatic mosaicism and so dilute the effect of mutation.) [Neurology. 2011 Feb 15;76(7):594-600] A hallmark of these syndromes is that seizures are frequently associated with fever. [Epilepsy Behav. 2011 Aug;21(4):446-8; Epilepsia. 2011 Apr;52 Suppl 2:3-9; Epilepsia, 46(Suppl. 10):41–47, 2005] A common SCN1A polymorphism has been associated with the generally benign febrile seizures that affect about one in thirty children and 10-15% of children in some ethnic groups. [Epilepsia. 2011 Jul 18]

    Recent gene expression studies quite clearly explain the delayed onset of these SCN1A-associated syndromes. For example, Dravet syndrome happens to manifest most commonly during the period when children receive routine vaccinations—which also happens to be when the expression of SCN1A increases from a low levels at birth to its maximal level. [Brain Res. 2011 May 10;1389:61-70] Seizure activity in mouse and rat pups that carry SCN1A mutations similarly follow the temporal pattern of the mutant gene’s expression. [J Biol Chem. 2010 March 26; 285(13): 9823–9834; J Neurosci. 2010 Apr 21;30(16):5744-53; Epilepsia. 2011 Apr;52 Suppl 2:59-61; Epilepsia. 2011 Apr;52 Suppl 2:59-61] Thus the defective protein, which is nearly absent at birth, increasingly populates the neurons—with dramatic results which in many cases include an initial febrile seizure.

    It’s clear that a pre-existing genetic change can be revealed by a fever that is caused by the appropriate immune response to vaccination or to natural infection—or even by a hot bath. [Brain Dev.2001 Nov;23(7):736-48] Susceptibility to SCN1A-associated febrile seizure develops some time before the onset of spontaneous afebrile seizure activity. [Proc Natl Acad Sci U S A. 2009 Mar 10;106(10):3994-9; Epilepsia. 2011 Apr;52 Suppl 2:59-61] Mice heterozyogous for SCN1A mutations (as in Dravet syndrome) developed seizures after a period of apparently normal development, but homozygous mice (with two copies of the mutant gene) developed seizures after a period of apparently normal development as SCN1A gene expression increased to its maximum—and then died, without any vaccine “trigger.” [J Biol Chem. 2010 March 26; 285(13): 9823–9834]

    In the first paper to show that alleged vaccine-induced encephalopathy could be explained as genetically-determined epilepsy, Berkovic et al argued, “[T]he role of vaccination as a significant trigger for the encephalopathy is unlikely for several reasons. First, although vaccination might trigger seizures as shown by the increased risk of febrile seizures on the day of [DPT] or MMR vaccination, there is no evidence of long-term adverse outcomes. Second, less than half our patients had documented fever with their first seizure, which indicates that fever is not essential. Third, our neuroimaging data showed no evidence of an inflammatory or destructive process. Finally, truncation and missense mutations reported in conserved parts of SCN1A have not been found in many hundreds of healthy patients. Thus, individuals with such mutations seem to develop SMEI or SMEB whether or not they are immunised in the first year of life.” [Lancet Neurol 2006; 5: 488–92]

    The authors of the Pace Environmental Law Review article mentioned above either ignored or did not understand the evidence from clinical practice, molecular biology, and genetics that has accumulated since those cases were compensated by the NVICP. The evidence emphatically refutes their claims.

  2. Sullivan September 1, 2011 at 08:54 #

    Brian,

    Sorry your comments were stick in spam so long.

  3. brian September 1, 2011 at 15:36 #

    Well, perhaps I should have just waited instead of posting the same comments three times over two days :)

    Please feel free to delete two of the the three iterations.

    • Sullivan September 1, 2011 at 20:17 #

      Sorry about that. It was late and I didn’t want to figure out which was the best of the three.

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