Vasovagal syncope: state or trait?

Purpose of Review: The absence of a satisfactory comprehensive theory for vasovagal syncope has prompted attention towards a possible genetic origin. There are several features of this trait that suggest a genetic origin. The purposes of this review are to present a rationale for considering a genetic origin and critically summarize recent findings.
Recent Findings: Key characteristics that suggest a genetic origin are incomplete effect in the population, a persistent clinical phenotype, and the absence of obvious infectious or autoimmune causes. There are familial pedigrees of vasovagal syncope, and statistical analyses of the impact of family history on the likelihood of an individual fainting that suggest an autosomal dominant transmission with incomplete penetrance. There is also evidence of sex-specific penetrance. Early candidate gene studies point towards involvement of sympathetic signal transduction in the physiologic cascade.
Summary: Several epidemiologic characteristics of vasovagal syncope suggest that it may have a genetic origin.