Researchers found that febrile seizures occurred in roughly one in every 1,000 children who were given the MMR vaccine and two genetic variants came to light that pointed to a higher risk of a febrile seizure in the second week following MMR vaccination.
Common variants associated with general and MMR vaccine–related febrile seizures
Bjarke Feenstra, Bjorn Pasternak, Frank Geller, Lisbeth Carstensen, et. al. Nature Genetics 46, 1274-1282; 26 October, 2014.
Febrile seizures represent a serious adverse event following measles, mumps and rubella (MMR) vaccination. We conducted a series of genome-wide association scans comparing children with MMR-related febrile seizures, children with febrile seizures unrelated to vaccination and controls with no history of febrile seizures. Two loci were distinctly associated with MMR-related febrile seizures. Furthermore, four loci were associated with febrile seizures in general, implicating the sodium channel genes and a region associated with magnesium levels.
MMR vaccination nearly triples the risk of febrile seizures within two weeks of vaccination, and some children are genetically vulnerable to this serious MMR-related adverse event.
Common variants associated with general and MMR vaccine-related febrile seizures
Feenstra B, Pasternak B, Geller F, et al. Nature Genetics 2014;46(12):1274-1282.
MMR vaccination nearly triples the risk of febrile seizures—a serious adverse event—within two weeks of vaccination. This study explored whether genetic variants might explain the increased risk by comparing children who experienced MMR-related febrile seizures to children who had “MMR-unrelated febrile seizures” as well as a control group free of seizures. The analysis identified two genetic loci “distinctly associated with febrile seizures as an adverse event following MMR vaccination”—and four more related to febrile seizures in general. The authors hypothesize a two-stage response whereby the MMR-related genetic variants induce fever and then the febrile seizure variants trigger the seizure response. They note the need for additional studies “to determine whether the variants are associated with response to other vaccines.”