JUST as the dispute over whether vaccines cause autism was dying down at last, a US government decision has added fresh fuel to the fire. Last week it emerged that the federal government is to compensate a couple who say that the regular childhood vaccines, given to their baby daughter in 2000, caused her to develop autism. Damages have not yet been set, but could exceed $1 million.
Significantly, the government鈥檚 decision says nothing about whether vaccines cause autism. Instead, government lawyers concluded only that vaccines aggravated a pre-existing cellular disorder in the child, causing brain damage that included features of autism. Nonetheless, anti-vaccination campaigners are claiming vindication. 鈥淚t鈥檚 official,鈥� wrote one autism blogger. 鈥淭he sky has fallen. The fat lady has sung. Pigs are flying.鈥�
Autism experts say it is unclear why compensation is being paid. Almost 5000 other families have lodged similar claims which are being considered by the court, but decades of research have failed to find any link between vaccines and autism and few experts thought that the government would pay up.
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聯It鈥檚 unclear why compensation is being paid. Decades of research have failed to find any link between vaccines and autism聰
Scientists say there is nothing in the medical history of the child in question to change that thinking. 鈥淚鈥檓 stunned that they decided to settle,鈥� says Jay Gargus, a paediatrician at the University of California, Irvine. Exactly why the US government did so is still being debated, as details of the decision have been sealed and the Department of 午夜福利1000集合 and Human Services won鈥檛 comment.
Whatever the government鈥檚 thinking, the worry is that the decision may undermine public confidence in vaccines, which is just recovering after recent scares over mercury and the measles, mumps and rubella (MMR) shot. On 29 February, for example, Republican presidential candidate John McCain used a query on the case as a chance to question whether mercury in vaccines could be linked to autism.
鈥淎 decision like this will definitely make parents more wary about vaccines,鈥� says Jaime DeVille, a paediatrician at the University of California, Los Angeles, and a member of the government鈥檚 childhood vaccines advisory committee.
According to internet newspaper The Huffington Post, which last week published leaked details of the court case from November, the child developed a fever after receiving scheduled vaccinations in 2000 for haemophilus influenzae, chickenpox, polio, MMR, diphtheria, pertussis, tetanus and polio, when she was 18 months old. Autism-like symptoms, such as poor communication skills, followed. In 2001 physicians concluded that the child, who has not been named, 鈥渄emonstrated features of autistic disorder鈥�.
It transpired that the child鈥檚 mitochondria, the powerhouses that provide cells with energy, were not working normally, and tests revealed a mutation in a gene linked to mitochondrial function. After studying her medical history, officials at the Department of 午夜福利1000集合 and Human Services concluded that the vaccines had 鈥渟ignificantly aggravated an underlying mitochondrial disorder, which predisposed her to deficits in energy metabolism鈥�, causing brain damage with 鈥溾��.
Proponents of a link between vaccines and autism have made much of the mitochondrial disorder, in part because researchers have wondered for at least a decade whether autism could be a mitochondrial disorder. Autism runs in families and some of the genes thought to be involved play a role in mitochondrial function. Biomarkers for mitochondrial dysfunction, such as a build-up of lactic acid, are also elevated in some autistic children. David Kirby, the journalist who revealed the decision, says that in an 鈥渋nformal survey鈥� of seven other children with cases pending all show signs of mitochondrial problems, though he did not reveal how he got this information.
Experts say these links do nothing to prove that autism originates in the mitochondria. 鈥淚t鈥檚 not surprising that mitochondrial function is abnormal,鈥� says Steven Novella, a neurologist at Yale University. 鈥淲ith neurodegenerative disorders almost any marker of cell health will be worse than in controls.鈥� Without more research, he adds, it is impossible to say whether the mitochondrial problems are the cause of the disease or its by-product (see 鈥淐an autism be a mitochondrial disease?鈥�). Those who argue otherwise, are 鈥渕aking multiple assumptions that are not established鈥�, Novella warns.
Further complications stem from confusion over the role vaccines played in the child鈥檚 condition. Severe inflammatory reactions are a rare but established side effect of vaccines, and they can damage the brain in many different ways, some of which produce symptoms similar to those seen in autism. The mitochondrial disorder might have prevented the child from dealing with her inflammation, but it is also possible that the child鈥檚 mitochondrial problems caused the inflammation and that the vaccines she received were irrelevant.
聯It is possible that the child鈥檚 mitochondrial problems caused the inflammation and the vaccines were irrelevant聰
Other experts added that parents should not be dissuaded from getting their children vaccinated just because of a court case. 鈥淲hat does this decision mean?鈥� says Paul Offit, a paediatrician at the Children鈥檚 Hospital of Philadelphia in Pennsylvania. 鈥淚t doesn鈥檛 mean anything. The question of whether vaccines cause autism is a scientific one, not a legal one.鈥�
Numerous scientific studies have addressed the question, adds Offit, and all concluded that there is no link. Government officials, including those at the Centers for Disease Control and Prevention in Atlanta, Georgia, also insisted the decision does nothing to change their thinking.
These caveats may, however, get lost as reaction to the decision evolves. Kevin Conway of Conway, Homer & Chin-Caplan in Boston, whose firm represents around 1200 autistic children with court cases pending, says he will start getting his clients tested for mitochondrial dysfunction. And Thomas Power, an attorney based in Portland, Oregon, says he would also like to see full details of the case, as they could help his cases of autistic children seeking compensation.
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Can autism be a mitochondrial disease?
FOR some years now, researchers have known that children with mitochondrial disorders can develop autism-like symptoms, or even full-blown autism. A 2005 study of 69 Portuguese children with autism found mitochondrial abnormalities that disrupted energy production in five of them, (Developmental Medicine and Child Neurology, ).
The big question is whether the girl whose family is due to receive damages would also have developed autism-like symptoms in the absence of vaccination (see main story).
Researchers contacted by New Scientist say that in very crude terms, children with mitochondrial disorders are especially at risk of neurological and muscular abnormalities because muscle and brain cells need so much energy. If mitochondria are faulty and don鈥檛 supply enough energy, these cells are damaged. Lack of energy can also lead to encephalopathy, or disruption of brain structure, which can in turn cause autism-like symptoms. 鈥淎nything that messes up development can cause something that looks like autism,鈥� says Lindsey Kent of the University of St Andrews in the UK. But such symptoms are unusual. Mostly, children present with a wide range of developmental disorders of varying severity.
Kent also points out that mitochondrial diseases are very rare 鈥� just 5.7 per 100,000 individuals worldwide 鈥� and the subsets of disorders linked with autism even rarer. Kent says she is surprised that the court ruled in favour of the girl, arguing that the symptoms would probably have developed whether or not she had been vaccinated. 鈥淪he has a clear mitochondrial genetic mutation, which is probably the cause of her developmental regression, autistic features and epilepsy,鈥� she says. 鈥淲hether or not the vaccine unmasked this will never be known, but it seems quite surprising.鈥�
Salvatore DiMauro, who has studied links between autism and mitochondrial mutations at Columbia University in New York, agrees. 鈥淢y guess is that if she had a mitochondrial mutation, sooner or later she would have shown something abnormal,鈥� he says.
DiMauro says it鈥檚 significant that the girl鈥檚 genetic mutation was in the 16S ribosomal RNA gene, because these are very rare. Only four others are known. The gene plays a pivotal role in protein production, so any mutation that damages this function could have a huge impact on other mitochondrial genes and energy production by cells. 鈥淚n the girl鈥檚 case it would be important to prove protein synthesis is disrupted,鈥� he says.
DiMauro adds that in children who are 鈥渆nergy-challenged鈥� because of mitochondrial disease, stresses including vaccination could trigger autism-like symptoms. 鈥淐hildren get worse in any stressful event, from having flu to having a vaccination,鈥� he says.
Kent says it鈥檚 imperative in the wake of the ruling that parents don鈥檛 lose confidence in vaccines. 鈥淭hat鈥檚 what concerns me more than anything,鈥� she says. 鈥淢y advice would be to carry on getting children vaccinated.鈥�
She says that screening for mitochondrial defects prior to vaccination would be very expensive, and unnecessary as most are very rare, and damage from mitochondrial disorders usually becomes apparent very early in infancy.
