Furthermore, HF patients harboring one or two Glu27 alleles in the ADRB2 Gln27Glu locus (the G allele) exhibit better responses to β-blockers than Gln27 (the C allele) homozygotes (HR, 0.25 for the GG genotype; HR, 0.36 for the CG genotype; and HR, 0.66 for the CC genotype) (Fig. 2i), consistent with previous reports41,43. Here, ADRB2 is linked to hydrops fetalis.