There have been occasional alarming reports of children developing epilepsy as a result of a vaccination. This has led in the past to problems with vaccine uptake, particularly among children who have close relations with epilepsy, who have been perceived to be more at risk.

In particular, vaccination for whooping cough (pertussis) has been implicated as a cause of a brain condition (called an encephalopathy) characterised by epileptic seizures that do not respond to medication and a loss of intellectual ability.

Researchers in Australia, led by the award-winning scientist
Professor Samuel Berkovic, noticed that in many of these cases, the types of seizures seen closely resembled another type of epilepsy called severe myoclonic epilepsy of infancy. This has a genetic basis: patients have altered versions of a gene called SCN1A. They therefore decided to test fourteen patients diagnosed with "vaccine encephalopathy" for this mutation.

Eleven out of the fourteen patients had a mutated version of the SCN1A gene. In nine cases, the patients' parents' DNA was available and was also tested: none of the mutations were inherited; they were all new mutations in the child's DNA. All fourteen patients' seizure symptoms were reassessed: all were found to have specific epilepsy syndromes which are not typically associated with damage due to vaccination.

The researchers, writing in the June issue of Lancet Neurology, concluded that cases of "vaccine encephalopathy" could in fact be cases of a genetically caused condition that had nothing to do with the vaccine. The gene mutation causing the condition is new, so that there is no history of epilepsy in the family of the patient. If these results are confirmed in larger studies, this could have major implications for the treatment of people believed to have "vaccine encephalopathy" and also for the perceived acceptability of vaccines across society.

This study highlights how fast epilepsy research is moving today. Ten years ago, SCN1A had not yet been implicated in causing epilepsy. Our understanding of how genes can cause epilepsy was only just beginning. We have come a long way since then, but there is still plenty to discover.