Human beta-2 adrenoceptor gene polymorphisms are highly frequent in obesity and associate with altered adipocyte beta-2 adrenoceptor function

Catecholamines play a central role in the regulation of energy expenditure, in part by stimulating lipid mobilization through lipolysis in fat cells, The beta-2 adrenoceptor (BAR-2) is a major lipolytic receptor in human fat cells, To determine whether known polymorphisms in codons 16, 27, and 164 of this receptor play a role in obesity and subcutaneous adipocyte BAR-2 lipolytic function, we investigated a group of 140 women with a large variation in body fat mass, Only the polymorphisms in codons 16 and 27 were common in the study population, The Gln27Glu polymorphism was markedly associated with obesity with a relative risk for obesity of similar to 7 and an odds ratio of similar to 10. Homozygotes for Glu27 had an average fat mass excess of 20 kg and similar to 50% larger fat cells than controls, However, no significant association with changes in BAR-2 function was observed, The Arg16Gly polymorphism was associated with altered BAR-2 function with Gly16 carriers showing a fivefold increased agonist sensitivity and without any change in BAR-2 expression, However, it was not significantly linked with obesity, These findings suggest that genetic variability in the human BAR-2 gene could be of major importance for obesity, energy expenditure, and lipolytic BAR-2 function in adipose tissue, at least in women.