Arg347Cys polymorphism of α1a-adrenergic receptor in vasovagal syncope. Case-control study in a Mexican population.

Background: Vasovagal syncope is a common clinical condition, consequential to reduced cerebral blood flow resulting from a failure in cardiovascular homeostasis during orthostasis. Blood pressure regulation is the basis for syncope development. In this regulation, the α1a-adrenergic receptor plays a major role. Some studies have found a positive correlation between the Arg347Cys polymorphism of the α1a-adrenergic receptor to hypertension and heart autonomic control. The goal of this study is to evaluate the possible association between the Arg347Cys α1a-adrenergic receptor polymorphism and vasovagal syncope in a Mexican population.

Methods/major Findings: A sample of 89 vasovagal syncope patients and 40 healthy controls were studied. Arg347Cys α1a-adrenergic receptor polymorphism was determined by the PCR-RFLP method. We found an increased frequency of genotype ArgArg in vasovagal syncope patients. In a logistic regression model significant associations were found in two genetic models, in codominant model (OR=13.21: CI 95% 3.69-54.99, p<0.001) and in additive model (OR=12.68: CI 95% 3.5-53.07, p<0.001) for ArgArg genotype with CysCys as reference.

Conclusions: Our data suggests an important participation of Arg347Cys polymorphism as susceptibility factor in patients with vasovagal syncope. ArgArg genotype could be a marker for vasovagal syncope susceptibility in the Mexican population.