1. 30% of the population suffers from reflex syncope, a major cause of transient loss of consciousness. Understanding genetic basis of this condition may offer new insight on therapeutic solution.
Evidence Rating Level: 2 (Good)
Study Rundown: Previously, population-based studies on familial aggregation of reflex syncope were lacking. This cohort study aims to investigate the familial risk of reflex syncope using 3 Swedish nationwide registers. While female sex was predisposed to experiencing reflex syncope independent of any gene variants, hereditary components may contribute to the pathogenesis of reflex syncope. Among first-, second-, and third-degree relatives, the relation degree was associated with higher familial risk of syncope. This study could inspire to new possible genetic approach to therapeutic management of syncope. One strength of this study is linking several Swedish population registers to generate a large sample size. Using validated national hospital discharge data also helps decrease recall biases. However, many patients did not seek medical care when experiencing transient syncope. The data may not represent the true occurrence rate in the general population. In addition to the genetic components, other key determinants of syncope such as organic and emotional triggers and environmental influence were not examined in this study.
In-Depth [retrospective cohort]: In this Swedish population-based family cohort study, the risk of reflex syncope was linked to increase with family members who also had reflex syncope. The risk was associated with the relationship degree and highest in twins and siblings with odds ratio for twins, siblings, half-siblings of affected individual being 2.39 (95%CI, 1.61-3.53), 1.8 (95%CI, 1.71-1.91). Logistic regression analyses also demonstrated associated between tetrachoric correlation, odd ratios and familial relationships. Notably, the proportion of individuals with syncope was consistently higher in women and younger patients, independent of familial relationship degrees. Exclusion of nonreflex syncope diagnoses did not impact syncope risk in affected families.
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