Head-up tilt induced syncope and adenosine A2A receptor gene polymorphism

Area of Science:

• Cardiology
• Genetics
• Pharmacology

Background:

• Unexplained syncope is often associated with elevated adenosine plasma levels and adenosine A(2A) receptor expression.
• The head-up tilt test (HUT) is a diagnostic tool for syncope, and its positive results correlate with adenosine pathway markers.

Purpose of the Study:

• To investigate the association between a common single nucleotide polymorphism (SNP) in the adenosine A(2A) receptor gene (c.1364 T>C) and unexplained syncope.
• To determine if this SNP influences HUT results and the incidence of syncopal episodes.

Main Methods:

• Genotyping for the adenosine A(2A) receptor gene polymorphism (c.1364 T>C) was performed on 105 patients with unexplained syncope undergoing HUT and 121 healthy controls.
• DNA was extracted from leucocytes for genotype determination (TT, CC, TC).

Main Results:

• A significant difference in genotype distribution was observed between patients with positive and negative HUT results (P < 0.0001).
• Fifty-two percent of patients with a positive HUT had the CC genotype, compared to 13.2% with a negative HUT.
• Patients with the CC genotype demonstrated a higher incidence of spontaneous syncopal episodes.

Conclusions:

• The CC variant of the adenosine A(2A) receptor gene is significantly associated with unexplained syncope and a positive HUT.
• This genetic finding may contribute to understanding the pathophysiology of syncope related to the adenosine pathway.