Association study of A2a adenosine receptor genetic polymorphism in panic disorder.

The adenosine A2a receptor (A2aAR) is thought to be implicated in the pathogenesis of panic disorder because caffeine, a potent antagonist for A2aAR, can precipitate panic attacks, and because disruption of the A2aAR gene increased anxiety-behaviors in mice. Recent studies demonstrated that the A2aAR 1976T > C genetic variant confers susceptibility to panic disorder though not by all studies. The present study tested the hypothesis that the A2aAR 1976T > C genetic variant confers susceptibility to panic disorder using a Chinese population of 104 panic disorder patients and 192 normal controls. We also tested whether the A2aAR 1976T > C polymorphism relates to the age of onset or subtype of panic disorders. Neither the distribution of the A2aAR 1976T > C genotypes (P = 0.296) or alleles (P = 0.864), nor the age of onset (P = 0.719) were significantly different among genotype groups. Furthermore, no association was demonstrated between this A2aAR polymorphism and either mitral-valve prolapse or agoraphobia in panic-disorder patients. These findings suggested that it is unlikely that the A2aAR 1976T > C polymorphism plays a major role in panic disorder pathogenesis in the Chinese population. The positive association between this polymorphism and panic disorder found in western population but not in Asian population suggests that this association could be ethnicity-dependent. The 1976C > T polymorphism may be in linkage disequilibrium with a functional variant that affects panic disorder, and the extent of this linkage disequilibrium is not similar for all ethnic populations.