Frequency of functionally important beta-2 adrenoceptor polymorphisms varies markedly among African-American, Caucasian and Chinese individuals

There are ethnic differences in the prevalence and severity of hypertension and asthma and in beta-2 adrenergic receptor (BAR2)-mediated vascular resp onses, Two common polymorphisms of the human BAR2, Arg16 to Gly and Gln27 t o Glu, are associated with alterations in BAR2 response, both in vitro and in vivo, Ethnic differences in disease manifestations and responses to trea tment may be explained by the altered frequency of BAR2 polymorphisms, To d etermine the relative frequencies of the Arg16 to Gly and Gln27 to Glu BAR2 polymorphisms in different ethnic groups we studied 415 (123 African-Ameri can, 188 Caucasian-American and 104 Chinese) healthy individuals. There was a marked interethnic difference in the frequency of the BAR2 polymorphisms among the ethnic groups, The Glu27 allele was more frequent in Caucasian-A merican (34.8%) than in African-American individuals (20.7%) (P = 0.0001) a nd much less frequent in Chinese individuals (7.2%) (P = 0.0001 versus Afri can-American or Caucasian-American). The homozygous Glu27 genotype was more frequent in Caucasian-American (15.4%) than African-American individuals ( 4.9%) (P = 0.003) and was not observed in Chinese. The Gly16 allele (54.3% versus 41.3%) and homozygous genotype (35.1% versus 18.3%) were more common in Caucasian-American than Chinese individuals (P = 0.003 for both). There is a marked ethnic difference in the frequency of these two common BAR2 po lymorphisms among African-American, Caucasian-American and Chinese individu als, with a markedly reduced frequency of the Glu27 polymorphism, the polym orphism associated with resistance to desensitization and increased BAR2 re sponses, in African-American and Chinese individuals, Such ethnic genotypic differences may explain previously observed alterations in the response to the BAR agonists in different ethnic groups. Pharmacogenetics 9:511-516 (C ) 1999 Lippincott Williams & Wilkins.