ADORA2B and pulmonary arterial hypertension: Moreover, an increased tricuspid regurgitation jet velocity (TRV > 2.5 m/s) and pulmonary hypertension defined by right heart catheterisation both independently conferred increased mortality in SCD.34 A preliminary genetic association study comparing patients with an elevated (n = 49) versus normal (n = 63) TRV revealed significant association with five SNPs within GALNT13 (p < 0.005), and a quantitative trait locus upstream of the adenosine-A2B receptor gene (ADORA2B)49, (Table 2).