Another human α2AR polymorphic variant, the Ins/Del322–325 α2CAR, which is quite frequent in African-American HF patients and which shows diminished sympatholytic capacity to inhibit NE release from cardiac SNS terminals, significantly affects HF risk and prognosis in patients, when this is examined in conjunction with the hyperfunctional Agr389 variant of the human β1AR [171]. Here, ADORA2A is linked to hydrops fetalis.