Similar results were observed in lymphocytes isolated from HF patients with the various β2AR genotypes: the inhibition of Gi signal by PTX significantly enhanced the β2AR-mediated elevation of cAMP levels in lymphocytes with the AA genotype (P < 0.05), whereas cells with AG or GG genotype were insensitive to PTX treatment (Fig. 3d). This evidence concerns the gene ADRB2 and hydrops fetalis.